<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:f395fde2-d1bd-43bf-b789-b22370aaa86f,g:cc18b8d7-0511-42d6-9f86-7dc5cead35aa-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.pentair.com/role/CondensedConsolidatedStatementsofChangesinEquity" xlink:type="simple" xlink:href="pnr-20240331.xsd#CondensedConsolidatedStatementsofChangesinEquity"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/CondensedConsolidatedStatementsofChangesinEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_1e0d0cde-a92b-42c0-ace9-595ab886bad6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_c118e1d4-03e9-4894-b85a-26a5151fb85d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_1e0d0cde-a92b-42c0-ace9-595ab886bad6" xlink:to="loc_us-gaap_StatementTable_c118e1d4-03e9-4894-b85a-26a5151fb85d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_c082dac1-2c94-480a-9527-4467e93b1ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_c118e1d4-03e9-4894-b85a-26a5151fb85d" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_c082dac1-2c94-480a-9527-4467e93b1ec3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_c082dac1-2c94-480a-9527-4467e93b1ec3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_c082dac1-2c94-480a-9527-4467e93b1ec3" xlink:to="loc_us-gaap_EquityComponentDomain_c082dac1-2c94-480a-9527-4467e93b1ec3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_c082dac1-2c94-480a-9527-4467e93b1ec3" xlink:to="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_d525779b-d38f-4f4a-a88c-fe9925ef72a0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:to="loc_us-gaap_CommonStockMember_d525779b-d38f-4f4a-a88c-fe9925ef72a0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_4c424a4e-359d-4193-a34a-a9173a641942" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_4c424a4e-359d-4193-a34a-a9173a641942" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_50d7195f-9ed2-4b8c-875b-638e4f69ea6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:to="loc_us-gaap_RetainedEarningsMember_50d7195f-9ed2-4b8c-875b-638e4f69ea6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e097d673-04c3-43bd-9324-107287e5178d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_32210597-fe15-46c9-b579-a025c6c01cab" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_e097d673-04c3-43bd-9324-107287e5178d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_2f5b3038-2f7a-4234-a368-d70243f7eb37" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1e0d0cde-a92b-42c0-ace9-595ab886bad6" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_2f5b3038-2f7a-4234-a368-d70243f7eb37" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_1e0d0cde-a92b-42c0-ace9-595ab886bad6" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_2e1fc995-9e20-4f51-9a01-120207bb43a3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_SharesOutstanding_2e1fc995-9e20-4f51-9a01-120207bb43a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_4a86bb9e-64e8-4f6d-9855-0843df081f05" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_4a86bb9e-64e8-4f6d-9855-0843df081f05" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProfitLoss_3f6b8639-9da1-4b42-8336-e59a5091e8e7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ProfitLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_ProfitLoss_3f6b8639-9da1-4b42-8336-e59a5091e8e7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_32cbdaa0-ff9c-42e3-ad35-021bc30e8bff" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_32cbdaa0-ff9c-42e3-ad35-021bc30e8bff" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStock_930f76c6-5faf-49da-be70-a89eb0105088" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DividendsCommonStock"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_DividendsCommonStock_930f76c6-5faf-49da-be70-a89eb0105088" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_037ee734-7001-4636-a748-bd8d6a84f6ab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_037ee734-7001-4636-a748-bd8d6a84f6ab" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_315e9e57-453a-4f43-b7b9-7645d61e5b8a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_315e9e57-453a-4f43-b7b9-7645d61e5b8a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_ad36b370-19f7-4fbf-8461-e3360c6c58ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_ad36b370-19f7-4fbf-8461-e3360c6c58ed" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_df4c26e5-cbf0-440c-b9dc-1dfa3f4d5c5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures_df4c26e5-cbf0-440c-b9dc-1dfa3f4d5c5e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SharesSurrenderedByEmployeesShares_97364afc-45bd-4ede-867b-7e4ee66cf5e3" xlink:href="pnr-20240331.xsd#pnr_SharesSurrenderedByEmployeesShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_pnr_SharesSurrenderedByEmployeesShares_97364afc-45bd-4ede-867b-7e4ee66cf5e3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SharesSurrenderedByEmployees_ce963aff-f030-487d-8c96-1d59fee28121" xlink:href="pnr-20240331.xsd#pnr_SharesSurrenderedByEmployees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_pnr_SharesSurrenderedByEmployees_ce963aff-f030-487d-8c96-1d59fee28121" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bac308a8-ceb7-4961-9426-e20c4691f1f8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_c7eece1f-7643-40ca-8ef4-a85f9849ac62" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_bac308a8-ceb7-4961-9426-e20c4691f1f8" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_4d312708-e09b-4e9d-be51-6ad6ba647ddf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_61061add-6647-4f21-8f6d-78477ea447d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RevenueGeographicNetSalesInformationbySegmentDetails" xlink:type="simple" xlink:href="pnr-20240331.xsd#RevenueGeographicNetSalesInformationbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RevenueGeographicNetSalesInformationbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_95c65314-0557-4312-bab0-9f64207e1890" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_2970e207-50e4-4614-a29f-076230b043d2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_95c65314-0557-4312-bab0-9f64207e1890" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_2970e207-50e4-4614-a29f-076230b043d2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_2970e207-50e4-4614-a29f-076230b043d2" xlink:to="loc_srt_StatementGeographicalAxis_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea" xlink:to="loc_srt_SegmentGeographicalDomain_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_1c8c92d4-c23d-48e1-9f62-3bfbddd387ea" xlink:to="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_e757d37b-396c-47bd-a69b-bb171de8d6b3" xlink:href="https://xbrl.sec.gov/country/2024/country-2024.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:to="loc_country_US_e757d37b-396c-47bd-a69b-bb171de8d6b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WesternEuropeMember_04ed3b1e-660e-4d6d-a217-859c50dee340" xlink:href="pnr-20240331.xsd#pnr_WesternEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:to="loc_pnr_WesternEuropeMember_04ed3b1e-660e-4d6d-a217-859c50dee340" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DevelopingCountriesMember_14d9fe75-b165-4dee-a473-ae3bba2ab5c7" xlink:href="pnr-20240331.xsd#pnr_DevelopingCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:to="loc_pnr_DevelopingCountriesMember_14d9fe75-b165-4dee-a473-ae3bba2ab5c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherDevelopedCountriesMember_fece812a-3af2-45ea-87ff-79bedc9c93b6" xlink:href="pnr-20240331.xsd#pnr_OtherDevelopedCountriesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_5096df71-3260-4565-909d-e029bfc8e1c2" xlink:to="loc_pnr_OtherDevelopedCountriesMember_fece812a-3af2-45ea-87ff-79bedc9c93b6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_1b2149f6-426e-4b42-86c9-7e31a0aabbf3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_2970e207-50e4-4614-a29f-076230b043d2" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_1b2149f6-426e-4b42-86c9-7e31a0aabbf3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_1b2149f6-426e-4b42-86c9-7e31a0aabbf3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_1b2149f6-426e-4b42-86c9-7e31a0aabbf3" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_1b2149f6-426e-4b42-86c9-7e31a0aabbf3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_7f85ce1f-8ed5-402f-a900-80c867f2e98f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_1b2149f6-426e-4b42-86c9-7e31a0aabbf3" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_7f85ce1f-8ed5-402f-a900-80c867f2e98f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ResidentialSectorMember_b62d78ca-a542-4c2a-bf3e-c9b03d39b5ed" xlink:href="pnr-20240331.xsd#pnr_ResidentialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_7f85ce1f-8ed5-402f-a900-80c867f2e98f" xlink:to="loc_pnr_ResidentialSectorMember_b62d78ca-a542-4c2a-bf3e-c9b03d39b5ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_CommercialSectorMember_417f73ac-3139-4a3d-80ba-c29dad59989a" xlink:href="pnr-20240331.xsd#pnr_CommercialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_7f85ce1f-8ed5-402f-a900-80c867f2e98f" xlink:to="loc_pnr_CommercialSectorMember_417f73ac-3139-4a3d-80ba-c29dad59989a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IndustrialSectorMember_6c532673-c1e5-4333-8e0b-5ac7c0e608a5" xlink:href="pnr-20240331.xsd#pnr_IndustrialSectorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_7f85ce1f-8ed5-402f-a900-80c867f2e98f" xlink:to="loc_pnr_IndustrialSectorMember_6c532673-c1e5-4333-8e0b-5ac7c0e608a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e4423de6-cfe9-4df4-a50b-37c98665d87a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_95c65314-0557-4312-bab0-9f64207e1890" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_e4423de6-cfe9-4df4-a50b-37c98665d87a" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RevenuePerformanceObligationsDetails" xlink:type="simple" xlink:href="pnr-20240331.xsd#RevenuePerformanceObligationsDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RevenuePerformanceObligationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_ceb5b7e3-ed40-4a04-afa2-efb18e651cd8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_ceb5b7e3-ed40-4a04-afa2-efb18e651cd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:to="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_dec5a232-7f76-4bba-bd85-b2a4d9f76b51_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:to="loc_srt_RangeMember_dec5a232-7f76-4bba-bd85-b2a4d9f76b51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:to="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ec0765e2-0114-4712-9b97-472a8c2e6c4a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:to="loc_srt_MinimumMember_ec0765e2-0114-4712-9b97-472a8c2e6c4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_70f081a0-0f7a-4fc6-9868-2e10bd2a2919" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:to="loc_srt_MaximumMember_70f081a0-0f7a-4fc6-9868-2e10bd2a2919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_1d5236d8-4ce4-47b9-9e18-d975002cb405" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_1d5236d8-4ce4-47b9-9e18-d975002cb405" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4311bc4b-e7f9-47f9-9ab6-07581d08dd35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4311bc4b-e7f9-47f9-9ab6-07581d08dd35" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RevenuePerformanceObligationsDetails_1" xlink:type="simple" xlink:href="pnr-20240331.xsd#RevenuePerformanceObligationsDetails_1"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RevenuePerformanceObligationsDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_907fbe8e-b3e7-4545-838f-0c9027917dfc" xlink:to="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_dec5a232-7f76-4bba-bd85-b2a4d9f76b51_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:to="loc_srt_RangeMember_dec5a232-7f76-4bba-bd85-b2a4d9f76b51_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_dec5a232-7f76-4bba-bd85-b2a4d9f76b51" xlink:to="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_ec0765e2-0114-4712-9b97-472a8c2e6c4a" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:to="loc_srt_MinimumMember_ec0765e2-0114-4712-9b97-472a8c2e6c4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_70f081a0-0f7a-4fc6-9868-2e10bd2a2919" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_ced1210d-e5b8-4d27-830f-e9359a6b98ce" xlink:to="loc_srt_MaximumMember_70f081a0-0f7a-4fc6-9868-2e10bd2a2919" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_1d5236d8-4ce4-47b9-9e18-d975002cb405" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_1d5236d8-4ce4-47b9-9e18-d975002cb405" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4311bc4b-e7f9-47f9-9ab6-07581d08dd35" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_17db6f12-52ba-430e-b0da-d0d612a55583" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_4311bc4b-e7f9-47f9-9ab6-07581d08dd35" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansScheduleofSharebasedCompensationExpenseDetails" xlink:type="simple" xlink:href="pnr-20240331.xsd#SharePlansScheduleofSharebasedCompensationExpenseDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansScheduleofSharebasedCompensationExpenseDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10c18f04-4aec-4ddb-828a-8a1779de7e13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_09029006-d18f-452f-9fd0-40148a7b2045" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10c18f04-4aec-4ddb-828a-8a1779de7e13" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_09029006-d18f-452f-9fd0-40148a7b2045" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_25011611-ab38-404a-978d-cdee3af2e394" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_09029006-d18f-452f-9fd0-40148a7b2045" xlink:to="loc_us-gaap_AwardTypeAxis_25011611-ab38-404a-978d-cdee3af2e394" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25011611-ab38-404a-978d-cdee3af2e394_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_25011611-ab38-404a-978d-cdee3af2e394" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_25011611-ab38-404a-978d-cdee3af2e394_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0bfbe66c-5257-4485-9115-3a77d29dc799" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_25011611-ab38-404a-978d-cdee3af2e394" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0bfbe66c-5257-4485-9115-3a77d29dc799" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_bd0da5a1-a07f-4b3f-8b68-0419c0fedcaf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0bfbe66c-5257-4485-9115-3a77d29dc799" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_bd0da5a1-a07f-4b3f-8b68-0419c0fedcaf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember_afcc039c-8039-4a32-95ce-f04a8f608579" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0bfbe66c-5257-4485-9115-3a77d29dc799" xlink:to="loc_us-gaap_StockOptionMember_afcc039c-8039-4a32-95ce-f04a8f608579" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_da4fef98-db63-4d9d-91bd-c65003b1ffbf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_0bfbe66c-5257-4485-9115-3a77d29dc799" xlink:to="loc_us-gaap_PerformanceSharesMember_da4fef98-db63-4d9d-91bd-c65003b1ffbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensation_c2fb6e01-6632-463b-84d1-710bacbce392" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_10c18f04-4aec-4ddb-828a-8a1779de7e13" xlink:to="loc_us-gaap_ShareBasedCompensation_c2fb6e01-6632-463b-84d1-710bacbce392" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SharePlansAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#SharePlansAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SharePlansAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_90cd96d7-20bb-4615-a179-38145392e221" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_90cd96d7-20bb-4615-a179-38145392e221" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_67dc7a25-4fe9-442c-a5d1-998a8d8f6194" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_90cd96d7-20bb-4615-a179-38145392e221" xlink:to="loc_us-gaap_PlanNameAxis_67dc7a25-4fe9-442c-a5d1-998a8d8f6194" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_67dc7a25-4fe9-442c-a5d1-998a8d8f6194_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_67dc7a25-4fe9-442c-a5d1-998a8d8f6194" xlink:to="loc_us-gaap_PlanNameDomain_67dc7a25-4fe9-442c-a5d1-998a8d8f6194_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_9ba55f54-b67a-4c44-bc00-4859f42f4bfd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_67dc7a25-4fe9-442c-a5d1-998a8d8f6194" xlink:to="loc_us-gaap_PlanNameDomain_9ba55f54-b67a-4c44-bc00-4859f42f4bfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TwoThousandTwentyShareAndIncentivePlanMember_40e5ea50-45e0-4d79-98c9-9bea1f1fc807" xlink:href="pnr-20240331.xsd#pnr_TwoThousandTwentyShareAndIncentivePlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_9ba55f54-b67a-4c44-bc00-4859f42f4bfd" xlink:to="loc_pnr_TwoThousandTwentyShareAndIncentivePlanMember_40e5ea50-45e0-4d79-98c9-9bea1f1fc807" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_d90700ed-f728-4aa0-9d2b-0de85de3752f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_90cd96d7-20bb-4615-a179-38145392e221" xlink:to="loc_us-gaap_AwardTypeAxis_d90700ed-f728-4aa0-9d2b-0de85de3752f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d90700ed-f728-4aa0-9d2b-0de85de3752f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_d90700ed-f728-4aa0-9d2b-0de85de3752f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_d90700ed-f728-4aa0-9d2b-0de85de3752f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6af90759-6d1e-40f1-a83d-1c08d8680192" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_d90700ed-f728-4aa0-9d2b-0de85de3752f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6af90759-6d1e-40f1-a83d-1c08d8680192" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_8e0f8e44-4f20-4d4f-8eaa-4a5874e00c15" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6af90759-6d1e-40f1-a83d-1c08d8680192" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_8e0f8e44-4f20-4d4f-8eaa-4a5874e00c15" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember_8847023f-ddef-4ca7-b2e4-19287e63da02" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6af90759-6d1e-40f1-a83d-1c08d8680192" xlink:to="loc_us-gaap_StockOptionMember_8847023f-ddef-4ca7-b2e4-19287e63da02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_5d375834-4f55-40be-af49-71f86f7df3e9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_6af90759-6d1e-40f1-a83d-1c08d8680192" xlink:to="loc_us-gaap_PerformanceSharesMember_5d375834-4f55-40be-af49-71f86f7df3e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_08760050-3874-416a-aa44-3c5259d4744c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod_08760050-3874-416a-aa44-3c5259d4744c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_136d2bd0-d5a5-4037-b547-7ab207f5e365" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_136d2bd0-d5a5-4037-b547-7ab207f5e365" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_6c67836c-ec41-41a4-9cc1-1a86e20ba401" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_6c67836c-ec41-41a4-9cc1-1a86e20ba401" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e77679ec-744e-48ed-ae27-36ed86a8d3bc" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_e77679ec-744e-48ed-ae27-36ed86a8d3bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_c068a266-1d71-4a80-85a7-68d95fc7cd4c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_13ee71ed-9060-4c40-b5a3-af184db9840e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_c068a266-1d71-4a80-85a7-68d95fc7cd4c" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RestructuringandTransformationProgramCostsIncludedinSellingGeneralAdministrativeExpensesDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#RestructuringandTransformationProgramCostsIncludedinSellingGeneralAdministrativeExpensesDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RestructuringandTransformationProgramCostsIncludedinSellingGeneralAdministrativeExpensesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_f5122433-910f-4c07-9215-ed89d80bab09" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_c1506bb7-f50e-471c-ad18-b5f5146d4d00" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_f5122433-910f-4c07-9215-ed89d80bab09" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_c1506bb7-f50e-471c-ad18-b5f5146d4d00" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_3f8c20f1-34f4-441e-b1b6-51998afc1a2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_c1506bb7-f50e-471c-ad18-b5f5146d4d00" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_3f8c20f1-34f4-441e-b1b6-51998afc1a2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_3f8c20f1-34f4-441e-b1b6-51998afc1a2d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_3f8c20f1-34f4-441e-b1b6-51998afc1a2d" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_3f8c20f1-34f4-441e-b1b6-51998afc1a2d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_0943b079-baef-4683-ac89-44140e152240" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_3f8c20f1-34f4-441e-b1b6-51998afc1a2d" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_0943b079-baef-4683-ac89-44140e152240" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeveranceAndRelatedCostsMember_3653fbfa-c6b8-4167-9ef6-ce2a66d54e63" xlink:href="pnr-20240331.xsd#pnr_SeveranceAndRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_0943b079-baef-4683-ac89-44140e152240" xlink:to="loc_pnr_SeveranceAndRelatedCostsMember_3653fbfa-c6b8-4167-9ef6-ce2a66d54e63" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherRestructuringMember_374d8957-8b96-4694-be5c-d7b84894af38" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherRestructuringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_0943b079-baef-4683-ac89-44140e152240" xlink:to="loc_us-gaap_OtherRestructuringMember_374d8957-8b96-4694-be5c-d7b84894af38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeAxis_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a" xlink:href="pnr-20240331.xsd#pnr_TransformationTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_c1506bb7-f50e-471c-ad18-b5f5146d4d00" xlink:to="loc_pnr_TransformationTypeAxis_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeDomain_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a_default" xlink:href="pnr-20240331.xsd#pnr_TransformationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_pnr_TransformationTypeAxis_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a" xlink:to="loc_pnr_TransformationTypeDomain_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationTypeDomain_1b3c0df5-d35f-4f62-9f74-cca5753b5a38" xlink:href="pnr-20240331.xsd#pnr_TransformationTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_pnr_TransformationTypeAxis_1a69e3ea-b6b9-4233-af6c-51cf61d29e7a" xlink:to="loc_pnr_TransformationTypeDomain_1b3c0df5-d35f-4f62-9f74-cca5753b5a38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeveranceAndRelatedCostsMember_92c696bf-67e0-4c6f-b088-73a843794fe8" xlink:href="pnr-20240331.xsd#pnr_SeveranceAndRelatedCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_TransformationTypeDomain_1b3c0df5-d35f-4f62-9f74-cca5753b5a38" xlink:to="loc_pnr_SeveranceAndRelatedCostsMember_92c696bf-67e0-4c6f-b088-73a843794fe8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherTransformationMember_cca48b69-2a3c-4ba1-8067-7c9e8f6cf4fa" xlink:href="pnr-20240331.xsd#pnr_OtherTransformationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_TransformationTypeDomain_1b3c0df5-d35f-4f62-9f74-cca5753b5a38" xlink:to="loc_pnr_OtherTransformationMember_cca48b69-2a3c-4ba1-8067-7c9e8f6cf4fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_9327a65e-3629-4e6e-b03c-d25f3097d4ad" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_f5122433-910f-4c07-9215-ed89d80bab09" xlink:to="loc_us-gaap_RestructuringCharges_9327a65e-3629-4e6e-b03c-d25f3097d4ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationCosts_b583c1d5-4592-4e8a-aae3-192b9246e802" xlink:href="pnr-20240331.xsd#pnr_TransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_f5122433-910f-4c07-9215-ed89d80bab09" xlink:to="loc_pnr_TransformationCosts_b583c1d5-4592-4e8a-aae3-192b9246e802" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TotalRestructuringAndTransformationCosts_7e952a01-aa3e-4225-a22d-c6b67ba5904e" xlink:href="pnr-20240331.xsd#pnr_TotalRestructuringAndTransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_f5122433-910f-4c07-9215-ed89d80bab09" xlink:to="loc_pnr_TotalRestructuringAndTransformationCosts_7e952a01-aa3e-4225-a22d-c6b67ba5904e" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/RestructuringandTransformationProgramRestructuringCostsbySegmentDetails" xlink:type="simple" xlink:href="pnr-20240331.xsd#RestructuringandTransformationProgramRestructuringCostsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/RestructuringandTransformationProgramRestructuringCostsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_caff2350-8544-4de4-a4b9-a539da9a5c43" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_d43a339a-3b1f-432b-8922-5bc8403d4551" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_caff2350-8544-4de4-a4b9-a539da9a5c43" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_d43a339a-3b1f-432b-8922-5bc8403d4551" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0b324c7d-b6be-4b7b-9898-699200ebc0a1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_d43a339a-3b1f-432b-8922-5bc8403d4551" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0b324c7d-b6be-4b7b-9898-699200ebc0a1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0b324c7d-b6be-4b7b-9898-699200ebc0a1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0b324c7d-b6be-4b7b-9898-699200ebc0a1" xlink:to="loc_us-gaap_SegmentDomain_0b324c7d-b6be-4b7b-9898-699200ebc0a1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0b324c7d-b6be-4b7b-9898-699200ebc0a1" xlink:to="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IndustrialFlowTechnologiesMember_6381c138-e40f-4b2e-8c2b-a61fe6a56bf3" xlink:href="pnr-20240331.xsd#pnr_IndustrialFlowTechnologiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:to="loc_pnr_IndustrialFlowTechnologiesMember_6381c138-e40f-4b2e-8c2b-a61fe6a56bf3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_bea17209-0b36-47a0-8c84-550715ccc793" xlink:href="pnr-20240331.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:to="loc_pnr_WaterSolutionsMember_bea17209-0b36-47a0-8c84-550715ccc793" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_d298e551-a3bf-4c75-af2d-8be9dca87758" xlink:href="pnr-20240331.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:to="loc_pnr_PoolMember_d298e551-a3bf-4c75-af2d-8be9dca87758" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherMember_e5485838-a469-4b23-bddb-b5727f5403c7" xlink:href="pnr-20240331.xsd#pnr_OtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:to="loc_pnr_OtherMember_e5485838-a469-4b23-bddb-b5727f5403c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_8ad09adb-627f-4e59-baae-a4b41b37a39b" xlink:href="pnr-20240331.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8c39aa5c-560c-45d6-9c61-7e8f917b9e32" xlink:to="loc_pnr_FlowMember_8ad09adb-627f-4e59-baae-a4b41b37a39b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TotalRestructuringAndTransformationCosts_67fb55e7-9cb8-4771-8d0b-9716812678d4" xlink:href="pnr-20240331.xsd#pnr_TotalRestructuringAndTransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_caff2350-8544-4de4-a4b9-a539da9a5c43" xlink:to="loc_pnr_TotalRestructuringAndTransformationCosts_67fb55e7-9cb8-4771-8d0b-9716812678d4" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsChangesinCarryingAmountofGoodwillbySegmentDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_786b01b5-19a4-4f5e-9c73-74eb4638b7e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_1ae674ae-79ee-4538-b98c-ecb4d89dd349" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_786b01b5-19a4-4f5e-9c73-74eb4638b7e5" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_1ae674ae-79ee-4538-b98c-ecb4d89dd349" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0a828c9c-83d2-4f67-9f37-5ed6267ecf29" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_1ae674ae-79ee-4538-b98c-ecb4d89dd349" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0a828c9c-83d2-4f67-9f37-5ed6267ecf29" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0a828c9c-83d2-4f67-9f37-5ed6267ecf29_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0a828c9c-83d2-4f67-9f37-5ed6267ecf29" xlink:to="loc_us-gaap_SegmentDomain_0a828c9c-83d2-4f67-9f37-5ed6267ecf29_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0a828c9c-83d2-4f67-9f37-5ed6267ecf29" xlink:to="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IndustrialFlowTechnologiesMember_4ec2f1ed-62db-4f5a-9c55-36a3980b0b9c" xlink:href="pnr-20240331.xsd#pnr_IndustrialFlowTechnologiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:to="loc_pnr_IndustrialFlowTechnologiesMember_4ec2f1ed-62db-4f5a-9c55-36a3980b0b9c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_3b5e1537-50c9-4003-aed9-3c3f925063c7" xlink:href="pnr-20240331.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:to="loc_pnr_WaterSolutionsMember_3b5e1537-50c9-4003-aed9-3c3f925063c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_f2777d37-2cd6-430a-8bba-21a3e2d60319" xlink:href="pnr-20240331.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:to="loc_pnr_PoolMember_f2777d37-2cd6-430a-8bba-21a3e2d60319" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_0e2027ed-d051-4ab0-85e4-e61a87fd4277" xlink:href="pnr-20240331.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2d2a5653-27a4-410c-8abc-98519922356a" xlink:to="loc_pnr_FlowMember_0e2027ed-d051-4ab0-85e4-e61a87fd4277" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillRollForward_4167e28a-be1f-425a-a094-ec9d1c3140c8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_786b01b5-19a4-4f5e-9c73-74eb4638b7e5" xlink:to="loc_us-gaap_GoodwillRollForward_4167e28a-be1f-425a-a094-ec9d1c3140c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_90b9b9a8-0d20-451e-94dc-ab096d158570" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_4167e28a-be1f-425a-a094-ec9d1c3140c8" xlink:to="loc_us-gaap_Goodwill_90b9b9a8-0d20-451e-94dc-ab096d158570" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillOtherIncreaseDecrease_140c45a0-7d31-443e-88dd-d14236859a58" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_GoodwillOtherIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillRollForward_4167e28a-be1f-425a-a094-ec9d1c3140c8" xlink:to="loc_us-gaap_GoodwillOtherIncreaseDecrease_140c45a0-7d31-443e-88dd-d14236859a58" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_14fa42ff-996f-4e00-9950-c0e9163a188e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Goodwill"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsDetailofIdentifiableIntangibleAssetsDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#GoodwillandOtherIdentifiableIntangibleAssetsDetailofIdentifiableIntangibleAssetsDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/GoodwillandOtherIdentifiableIntangibleAssetsDetailofIdentifiableIntangibleAssetsDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:href="pnr-20240331.xsd#pnr_AcquiredIntangibleAssetsByMajorClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_3d865f56-a0aa-4b8c-b4a1-253abdcc05c9" xlink:href="pnr-20240331.xsd#pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_3d865f56-a0aa-4b8c-b4a1-253abdcc05c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1aa33454-2957-405f-8b8a-b688cc442f2e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_ScheduleOfAcquiredIntangibleAssetsByMajorClassTable_3d865f56-a0aa-4b8c-b4a1-253abdcc05c9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1aa33454-2957-405f-8b8a-b688cc442f2e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1aa33454-2957-405f-8b8a-b688cc442f2e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1aa33454-2957-405f-8b8a-b688cc442f2e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_1aa33454-2957-405f-8b8a-b688cc442f2e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad60d9cc-192a-4063-9009-49622aa00936" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_1aa33454-2957-405f-8b8a-b688cc442f2e" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad60d9cc-192a-4063-9009-49622aa00936" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_815d1a1d-effe-4397-bcb1-e288c850414b" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad60d9cc-192a-4063-9009-49622aa00936" xlink:to="loc_us-gaap_CustomerRelationshipsMember_815d1a1d-effe-4397-bcb1-e288c850414b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PatentedTechnologyMember_7f6e3d02-20d8-4675-b00d-b02b0f50984a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PatentedTechnologyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad60d9cc-192a-4063-9009-49622aa00936" xlink:to="loc_us-gaap_PatentedTechnologyMember_7f6e3d02-20d8-4675-b00d-b02b0f50984a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeNamesMember_fcdb87df-d020-4003-a004-068e605d08cf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TradeNamesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_ad60d9cc-192a-4063-9009-49622aa00936" xlink:to="loc_us-gaap_TradeNamesMember_fcdb87df-d020-4003-a004-068e605d08cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_3e68b9ac-9da0-41cc-a01f-25675b2e9b00" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_3e68b9ac-9da0-41cc-a01f-25675b2e9b00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d406f4b2-9615-4ede-adbd-9aa9c2c5e86f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_d406f4b2-9615-4ede-adbd-9aa9c2c5e86f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_b415dddd-f85b-456b-94f2-b9e07bf7d3f6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_b415dddd-f85b-456b-94f2-b9e07bf7d3f6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_d6835a9c-8136-48bc-85f6-e050de3d82b7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsExcludingGoodwill_d6835a9c-8136-48bc-85f6-e050de3d82b7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_fa0daa87-b208-46f5-8927-16c73c8a1bfe" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsGrossExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_IntangibleAssetsGrossExcludingGoodwill_fa0daa87-b208-46f5-8927-16c73c8a1bfe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_1211ec61-4a88-4b79-956e-74146924da2c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_AcquiredIntangibleAssetsByMajorClassLineItems_628b6397-c0cc-4c75-ab87-92bf567d0fcf" xlink:to="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_1211ec61-4a88-4b79-956e-74146924da2c" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DebtDebtandAverageInterestRatesonDebtOutstandingDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#DebtDebtandAverageInterestRatesonDebtOutstandingDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DebtDebtandAverageInterestRatesonDebtOutstandingDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_f2a7c965-536a-4259-9d0e-dba7eee3cf5d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:to="loc_us-gaap_DebtInstrumentTable_f2a7c965-536a-4259-9d0e-dba7eee3cf5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_f2572572-680a-48c7-9563-dfb89b465038" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f2a7c965-536a-4259-9d0e-dba7eee3cf5d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_f2572572-680a-48c7-9563-dfb89b465038" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_f2572572-680a-48c7-9563-dfb89b465038_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f2572572-680a-48c7-9563-dfb89b465038" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_f2572572-680a-48c7-9563-dfb89b465038_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_8d62b7d7-b7fa-493c-9a97-a5ba944a4fa9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_f2572572-680a-48c7-9563-dfb89b465038" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_8d62b7d7-b7fa-493c-9a97-a5ba944a4fa9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_3877e223-6744-49b9-a61f-30a37c066fdf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8d62b7d7-b7fa-493c-9a97-a5ba944a4fa9" xlink:to="loc_us-gaap_LineOfCreditMember_3877e223-6744-49b9-a61f-30a37c066fdf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansMember_9b6665b0-26f6-4cfc-b185-90ce0b69b16d" xlink:href="pnr-20240331.xsd#pnr_TermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8d62b7d7-b7fa-493c-9a97-a5ba944a4fa9" xlink:to="loc_pnr_TermLoansMember_9b6665b0-26f6-4cfc-b185-90ce0b69b16d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_2ceebac2-fd7e-4590-846c-77834806342c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_8d62b7d7-b7fa-493c-9a97-a5ba944a4fa9" xlink:to="loc_us-gaap_SeniorNotesMember_2ceebac2-fd7e-4590-846c-77834806342c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f2a7c965-536a-4259-9d0e-dba7eee3cf5d" xlink:to="loc_us-gaap_CreditFacilityAxis_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59" xlink:to="loc_us-gaap_CreditFacilityDomain_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_947b6edc-d723-4ef6-b271-97eb0bc4d4ec" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_8a60014e-e2f5-4cfa-b8ef-b6e821d62f59" xlink:to="loc_us-gaap_CreditFacilityDomain_947b6edc-d723-4ef6-b271-97eb0bc4d4ec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2f5e156f-5e83-464a-8c57-e7c4de04e6d7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_947b6edc-d723-4ef6-b271-97eb0bc4d4ec" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2f5e156f-5e83-464a-8c57-e7c4de04e6d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_bd21bfbb-791a-476f-b8e2-8191e613741e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_f2a7c965-536a-4259-9d0e-dba7eee3cf5d" xlink:to="loc_us-gaap_DebtInstrumentAxis_bd21bfbb-791a-476f-b8e2-8191e613741e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_bd21bfbb-791a-476f-b8e2-8191e613741e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_bd21bfbb-791a-476f-b8e2-8191e613741e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_bd21bfbb-791a-476f-b8e2-8191e613741e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_bd21bfbb-791a-476f-b8e2-8191e613741e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansDue2023Member_40d6cc41-09be-4658-85bd-b27e548c8f58" xlink:href="pnr-20240331.xsd#pnr_TermLoansDue2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_TermLoansDue2023Member_40d6cc41-09be-4658-85bd-b27e548c8f58" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember_8dc05688-bd42-4c5d-8f18-eb265148f01c" xlink:href="pnr-20240331.xsd#pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_SeniorNotesFourPointSixFivePercentDueTwentyTwentyFiveMember_8dc05688-bd42-4c5d-8f18-eb265148f01c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotes4500Due2029Member_bfe67ca1-6079-477c-9427-9cab1ce621a9" xlink:href="pnr-20240331.xsd#pnr_SeniorNotes4500Due2029Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_SeniorNotes4500Due2029Member_bfe67ca1-6079-477c-9427-9cab1ce621a9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A5YearTermLoanFacilityMember_1a593c13-aa5b-495b-8a2a-7129517aae76" xlink:href="pnr-20240331.xsd#pnr_A5YearTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_A5YearTermLoanFacilityMember_1a593c13-aa5b-495b-8a2a-7129517aae76" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoans1033DueIn2024Member_24b6166e-b7c3-4992-99a4-f3f497dd33e2" xlink:href="pnr-20240331.xsd#pnr_TermLoans1033DueIn2024Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_TermLoans1033DueIn2024Member_24b6166e-b7c3-4992-99a4-f3f497dd33e2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_addd4516-ba3d-4864-976d-d1db443e9d4e" xlink:href="pnr-20240331.xsd#pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_800c1842-0c3e-458e-ae0b-5d927c381559" xlink:to="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_addd4516-ba3d-4864-976d-d1db443e9d4e" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_2c7bc223-cd0e-4b07-bb6b-86bb1b3eadbd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_2c7bc223-cd0e-4b07-bb6b-86bb1b3eadbd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_fa354848-e96a-4a31-856a-08615825bdd0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_fa354848-e96a-4a31-856a-08615825bdd0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_2a16cd4f-8238-4045-89ce-e371d1908980" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_2a16cd4f-8238-4045-89ce-e371d1908980" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_f3a85068-0453-43bc-bc71-4b4f47fced68" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_73f402df-be26-46e2-8104-b8b6ec5898a6" xlink:to="loc_us-gaap_LongTermDebt_f3a85068-0453-43bc-bc71-4b4f47fced68" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DebtAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#DebtAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DebtAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityAxis_4dc6a8a1-c31f-4442-9d53-04620a0a3221" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_us-gaap_LineOfCreditFacilityAxis_4dc6a8a1-c31f-4442-9d53-04620a0a3221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_4dc6a8a1-c31f-4442-9d53-04620a0a3221_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_4dc6a8a1-c31f-4442-9d53-04620a0a3221" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_4dc6a8a1-c31f-4442-9d53-04620a0a3221_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLenderDomain_1a9c6f92-3182-4846-9c6c-2cef062c787f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityLenderDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LineOfCreditFacilityAxis_4dc6a8a1-c31f-4442-9d53-04620a0a3221" xlink:to="loc_us-gaap_LineOfCreditFacilityLenderDomain_1a9c6f92-3182-4846-9c6c-2cef062c787f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_OtherCreditFacilitiesMember_81edf7f5-27a2-4098-9d8d-ceddeccd99e5" xlink:href="pnr-20240331.xsd#pnr_OtherCreditFacilitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLenderDomain_1a9c6f92-3182-4846-9c6c-2cef062c787f" xlink:to="loc_pnr_OtherCreditFacilitiesMember_81edf7f5-27a2-4098-9d8d-ceddeccd99e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_20bffe95-bffe-4e7a-bb65-15c7c3bfb401" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_20bffe95-bffe-4e7a-bb65-15c7c3bfb401" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_20bffe95-bffe-4e7a-bb65-15c7c3bfb401_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_20bffe95-bffe-4e7a-bb65-15c7c3bfb401" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_20bffe95-bffe-4e7a-bb65-15c7c3bfb401_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_d3856f88-1ca3-46ad-ab6a-c10c1916f1ac" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_20bffe95-bffe-4e7a-bb65-15c7c3bfb401" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_d3856f88-1ca3-46ad-ab6a-c10c1916f1ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_e0d1c645-5136-402c-85d6-9d3c18a5f258" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d3856f88-1ca3-46ad-ab6a-c10c1916f1ac" xlink:to="loc_us-gaap_LineOfCreditMember_e0d1c645-5136-402c-85d6-9d3c18a5f258" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansMember_f4fb75ee-aacd-4dfd-b6dd-f4a7be483767" xlink:href="pnr-20240331.xsd#pnr_TermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d3856f88-1ca3-46ad-ab6a-c10c1916f1ac" xlink:to="loc_pnr_TermLoansMember_f4fb75ee-aacd-4dfd-b6dd-f4a7be483767" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_5767e003-c9d3-4af4-8bdf-20079fba14f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_d3856f88-1ca3-46ad-ab6a-c10c1916f1ac" xlink:to="loc_us-gaap_SeniorNotesMember_5767e003-c9d3-4af4-8bdf-20079fba14f3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_us-gaap_CreditFacilityAxis_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4" xlink:to="loc_us-gaap_CreditFacilityDomain_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_b45bd613-9b94-4625-b079-51994512078a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_592e2448-5d6b-4dac-b7f8-d6ff9a80bfc4" xlink:to="loc_us-gaap_CreditFacilityDomain_b45bd613-9b94-4625-b079-51994512078a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_fd0a7d2c-9a84-4bbe-a978-c28392529613" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_b45bd613-9b94-4625-b079-51994512078a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_fd0a7d2c-9a84-4bbe-a978-c28392529613" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_srt_RangeAxis_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f" xlink:to="loc_srt_RangeMember_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_071d4f7a-dd22-4aab-9c6e-7444fc58e8e9" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_a4cff500-6ca4-4b85-8ccb-7eb9d4e1109f" xlink:to="loc_srt_RangeMember_071d4f7a-dd22-4aab-9c6e-7444fc58e8e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_65ac29ae-a98b-4bd8-ad75-675c234936e7" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_071d4f7a-dd22-4aab-9c6e-7444fc58e8e9" xlink:to="loc_srt_MinimumMember_65ac29ae-a98b-4bd8-ad75-675c234936e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_33ce2417-0883-4d80-9896-70c338236c11" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_071d4f7a-dd22-4aab-9c6e-7444fc58e8e9" xlink:to="loc_srt_MaximumMember_33ce2417-0883-4d80-9896-70c338236c11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_us-gaap_DebtInstrumentAxis_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_68daab9c-e62f-41a1-9264-36fcf5b83c51" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_59d385c6-ab42-46e8-9f6b-20fbb68cd8ed" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_68daab9c-e62f-41a1-9264-36fcf5b83c51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TermLoansDue2023Member_0ee5684b-a17f-400a-9c00-a03cd48f1401" xlink:href="pnr-20240331.xsd#pnr_TermLoansDue2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_68daab9c-e62f-41a1-9264-36fcf5b83c51" xlink:to="loc_pnr_TermLoansDue2023Member_0ee5684b-a17f-400a-9c00-a03cd48f1401" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_A5YearTermLoanFacilityMember_74a3248e-64d2-4c1c-8db9-5becc693c618" xlink:href="pnr-20240331.xsd#pnr_A5YearTermLoanFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_68daab9c-e62f-41a1-9264-36fcf5b83c51" xlink:to="loc_pnr_A5YearTermLoanFacilityMember_74a3248e-64d2-4c1c-8db9-5becc693c618" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_68d25fb2-1c25-4150-a007-19d2ab6574de" xlink:href="pnr-20240331.xsd#pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_68daab9c-e62f-41a1-9264-36fcf5b83c51" xlink:to="loc_pnr_SeniorNotesFivePointNinePercentDueTwentyThirtyTwoMember_68d25fb2-1c25-4150-a007-19d2ab6574de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_727d99e9-b7bd-40b3-b9b9-b65b03431f36" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_srt_CounterpartyNameAxis_727d99e9-b7bd-40b3-b9b9-b65b03431f36" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_727d99e9-b7bd-40b3-b9b9-b65b03431f36_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_727d99e9-b7bd-40b3-b9b9-b65b03431f36" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_727d99e9-b7bd-40b3-b9b9-b65b03431f36_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623adc0c-18f6-46b3-9964-3231d9be8d95" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_727d99e9-b7bd-40b3-b9b9-b65b03431f36" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623adc0c-18f6-46b3-9964-3231d9be8d95" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PentairPentairFinanceSRlPFSAMember_6a7a9c2b-54c2-4131-a63b-7d7787e44444" xlink:href="pnr-20240331.xsd#pnr_PentairPentairFinanceSRlPFSAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_623adc0c-18f6-46b3-9964-3231d9be8d95" xlink:to="loc_pnr_PentairPentairFinanceSRlPFSAMember_6a7a9c2b-54c2-4131-a63b-7d7787e44444" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_srt_StatementScenarioAxis_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e" xlink:to="loc_srt_ScenarioUnspecifiedDomain_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_7c6c5ecd-ca70-48cb-ad85-21c7890d4157" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_01f783de-3ff3-475c-bc7a-f3cfae2ebc0e" xlink:to="loc_srt_ScenarioUnspecifiedDomain_7c6c5ecd-ca70-48cb-ad85-21c7890d4157" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_d1909092-b3ba-4690-9dd5-fe92562ca9c0" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_7c6c5ecd-ca70-48cb-ad85-21c7890d4157" xlink:to="loc_srt_ScenarioForecastMember_d1909092-b3ba-4690-9dd5-fe92562ca9c0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_4136d471-28cc-4c6b-8fbe-fc7cf055391a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_8c14df57-d92a-45a4-8578-90ebe62e578e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_4136d471-28cc-4c6b-8fbe-fc7cf055391a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_4136d471-28cc-4c6b-8fbe-fc7cf055391a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_4136d471-28cc-4c6b-8fbe-fc7cf055391a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_4136d471-28cc-4c6b-8fbe-fc7cf055391a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_545899a5-1353-4775-af5d-6ed73cdb329f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_4136d471-28cc-4c6b-8fbe-fc7cf055391a" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_545899a5-1353-4775-af5d-6ed73cdb329f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_50e303eb-fa2d-4210-a56d-cfee68ccc457" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_545899a5-1353-4775-af5d-6ed73cdb329f" xlink:to="loc_us-gaap_SubsequentEventMember_50e303eb-fa2d-4210-a56d-cfee68ccc457" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5ac15aa8-64d5-417b-be25-ddba9626ce70" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_5ac15aa8-64d5-417b-be25-ddba9626ce70" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_639e6584-0ad0-4104-9321-b6da93c40ab8" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_639e6584-0ad0-4104-9321-b6da93c40ab8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_bce13bfb-a07f-40e5-a92a-cadc06e99710" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_bce13bfb-a07f-40e5-a92a-cadc06e99710" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit_785dafa2-be23-443b-aef4-b6f8025890e6" xlink:href="pnr-20240331.xsd#pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_LineofCreditFacilityAccordionFeatureIncreaseLimit_785dafa2-be23-443b-aef4-b6f8025890e6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentPeriodicPayment_19d87d02-caca-45ed-ad9a-ebdbd004172a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DebtInstrumentPeriodicPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_DebtInstrumentPeriodicPayment_19d87d02-caca-45ed-ad9a-ebdbd004172a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentCovenantUnrestrictedCash_0439e994-4217-4847-a668-48db9e702eef" xlink:href="pnr-20240331.xsd#pnr_DebtInstrumentCovenantUnrestrictedCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_DebtInstrumentCovenantUnrestrictedCash_0439e994-4217-4847-a668-48db9e702eef" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentLeverageRatioCovenant_cda21883-4bd1-43a7-832f-44e831d2d776" xlink:href="pnr-20240331.xsd#pnr_DebtInstrumentLeverageRatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_DebtInstrumentLeverageRatioCovenant_cda21883-4bd1-43a7-832f-44e831d2d776" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentLeverageRatioCovenantPeriod_3f371697-2832-41e2-a80c-b9749314a7da" xlink:href="pnr-20240331.xsd#pnr_DebtInstrumentLeverageRatioCovenantPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_DebtInstrumentLeverageRatioCovenantPeriod_3f371697-2832-41e2-a80c-b9749314a7da" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentCovenantNumberOfTestingPeriods_0e65ed71-34b9-418e-91ef-0821844fb278" xlink:href="pnr-20240331.xsd#pnr_DebtInstrumentCovenantNumberOfTestingPeriods"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_DebtInstrumentCovenantNumberOfTestingPeriods_0e65ed71-34b9-418e-91ef-0821844fb278" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DebtInstrumentEBITDARatioCovenant_de922e77-f926-444f-87c3-91b707fce0bc" xlink:href="pnr-20240331.xsd#pnr_DebtInstrumentEBITDARatioCovenant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_pnr_DebtInstrumentEBITDARatioCovenant_de922e77-f926-444f-87c3-91b707fce0bc" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_6083560a-ca55-42a0-aa3a-9ef0acebb7b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_LineOfCredit_6083560a-ca55-42a0-aa3a-9ef0acebb7b4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths_2c17072b-7cc5-4b8c-a193-39f5afb1dc52" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_a049cb11-10ff-4cd3-8fbe-c6c7f497bed5" xlink:to="loc_us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextRollingTwelveMonths_2c17072b-7cc5-4b8c-a193-39f5afb1dc52" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAdditionalInformationDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#DerivativesandFinancialInstrumentsAdditionalInformationDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAdditionalInformationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_0fa28e0e-6ccd-4daf-ace7-b85aca483813" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_6a961c26-724c-4833-933d-de9085674ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_0fa28e0e-6ccd-4daf-ace7-b85aca483813" xlink:to="loc_us-gaap_DerivativeTable_6a961c26-724c-4833-933d-de9085674ca4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_d64d5c82-8d66-42f1-8cf1-a21987452e40" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_6a961c26-724c-4833-933d-de9085674ca4" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_d64d5c82-8d66-42f1-8cf1-a21987452e40" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_d64d5c82-8d66-42f1-8cf1-a21987452e40_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d64d5c82-8d66-42f1-8cf1-a21987452e40" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_d64d5c82-8d66-42f1-8cf1-a21987452e40_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_d64d5c82-8d66-42f1-8cf1-a21987452e40" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_9fdc4898-affc-43bf-9c60-70a6a299c3ed" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:to="loc_us-gaap_ForeignExchangeContractMember_9fdc4898-affc-43bf-9c60-70a6a299c3ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CurrencySwapMember_93072f16-b74a-4e26-94b2-9c0b6b6dd4de" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CurrencySwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:to="loc_us-gaap_CurrencySwapMember_93072f16-b74a-4e26-94b2-9c0b6b6dd4de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_df010ff2-76e5-4865-a0a4-a833afa7f662" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:to="loc_us-gaap_InterestRateSwapMember_df010ff2-76e5-4865-a0a4-a833afa7f662" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_InterestRateCollarMember_4183158e-ea51-40a7-9002-4f453b679689" xlink:href="pnr-20240331.xsd#pnr_InterestRateCollarMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_0b5abc15-fde5-4759-b899-7521baf36759" xlink:to="loc_pnr_InterestRateCollarMember_4183158e-ea51-40a7-9002-4f453b679689" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_6962163b-854c-4add-a04e-ff63079100f3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0fa28e0e-6ccd-4daf-ace7-b85aca483813" xlink:to="loc_us-gaap_DerivativeNotionalAmount_6962163b-854c-4add-a04e-ff63079100f3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_12ddf94a-d49d-499e-b65a-840528838ce3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0fa28e0e-6ccd-4daf-ace7-b85aca483813" xlink:to="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_12ddf94a-d49d-499e-b65a-840528838ce3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_8d3ede0f-0e55-4a12-b81f-f421091fdf2d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_0fa28e0e-6ccd-4daf-ace7-b85aca483813" xlink:to="loc_us-gaap_AociLossCashFlowHedgeCumulativeGainLossAfterTax_8d3ede0f-0e55-4a12-b81f-f421091fdf2d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsRecordedAmountsandEstimatedFairValuesDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_2d538747-03f5-4075-9717-a273d900f696" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_d4ccf81c-2ae3-4965-9bc3-733da4681c13" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_2d538747-03f5-4075-9717-a273d900f696" xlink:to="loc_us-gaap_DerivativeTable_d4ccf81c-2ae3-4965-9bc3-733da4681c13" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_093deee2-581b-4cb7-92c7-f9c0751bf8c3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_d4ccf81c-2ae3-4965-9bc3-733da4681c13" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_093deee2-581b-4cb7-92c7-f9c0751bf8c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_093deee2-581b-4cb7-92c7-f9c0751bf8c3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_093deee2-581b-4cb7-92c7-f9c0751bf8c3" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_093deee2-581b-4cb7-92c7-f9c0751bf8c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_1f304bc7-cd81-445f-b8f0-0706951e4b4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_093deee2-581b-4cb7-92c7-f9c0751bf8c3" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_1f304bc7-cd81-445f-b8f0-0706951e4b4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c053ad54-c587-45cf-9fa0-46e2f159b969" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_1f304bc7-cd81-445f-b8f0-0706951e4b4f" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_c053ad54-c587-45cf-9fa0-46e2f159b969" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_ed3c836c-3aeb-44a1-9271-9f7b064f1e7c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_1f304bc7-cd81-445f-b8f0-0706951e4b4f" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_ed3c836c-3aeb-44a1-9271-9f7b064f1e7c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_e1482f44-3772-4bab-ae79-59ca093f0c6c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_1f304bc7-cd81-445f-b8f0-0706951e4b4f" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_e1482f44-3772-4bab-ae79-59ca093f0c6c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtPercentageBearingVariableInterestAmount_4f4a8303-16e7-4916-b077-39ab2dec05c2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtPercentageBearingVariableInterestAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2d538747-03f5-4075-9717-a273d900f696" xlink:to="loc_us-gaap_LongtermDebtPercentageBearingVariableInterestAmount_4f4a8303-16e7-4916-b077-39ab2dec05c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtPercentageBearingFixedInterestAmount_bbc12160-7347-46ae-9c0a-c84b72c2d02c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongtermDebtPercentageBearingFixedInterestAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2d538747-03f5-4075-9717-a273d900f696" xlink:to="loc_us-gaap_LongtermDebtPercentageBearingFixedInterestAmount_bbc12160-7347-46ae-9c0a-c84b72c2d02c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_bb81479e-fbb5-4909-8f98-c3d221f081b4" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_2d538747-03f5-4075-9717-a273d900f696" xlink:to="loc_us-gaap_LongTermDebt_bb81479e-fbb5-4909-8f98-c3d221f081b4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/DerivativesandFinancialInstrumentsAssetsandLiabilitiesMeasuredatFairValueDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a9aca55b-5e78-474a-86b6-59b3023ddd8c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a9aca55b-5e78-474a-86b6-59b3023ddd8c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f908e483-4009-480d-b797-df28ac4bb0b9" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a9aca55b-5e78-474a-86b6-59b3023ddd8c" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f908e483-4009-480d-b797-df28ac4bb0b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f908e483-4009-480d-b797-df28ac4bb0b9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f908e483-4009-480d-b797-df28ac4bb0b9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_f908e483-4009-480d-b797-df28ac4bb0b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_f908e483-4009-480d-b797-df28ac4bb0b9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_1902bedb-8829-4361-9a00-439043c93059" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_1902bedb-8829-4361-9a00-439043c93059" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_919a16d8-8177-4614-ac71-5e25aaaee9e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_919a16d8-8177-4614-ac71-5e25aaaee9e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_1b1791c7-bfea-4cd0-9f87-aa54e1129c4f" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_1b1791c7-bfea-4cd0-9f87-aa54e1129c4f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_6578c40b-e889-4547-b73d-5770cf6f5481" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_2cbad184-1d19-43b7-906f-6d7af1856863" xlink:to="loc_us-gaap_FairValueMeasuredAtNetAssetValuePerShareMember_6578c40b-e889-4547-b73d-5770cf6f5481" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_28379181-2f1f-4e7f-a34b-4de5e86d751c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueByMeasurementFrequencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a9aca55b-5e78-474a-86b6-59b3023ddd8c" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_28379181-2f1f-4e7f-a34b-4de5e86d751c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_28379181-2f1f-4e7f-a34b-4de5e86d751c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_28379181-2f1f-4e7f-a34b-4de5e86d751c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_28379181-2f1f-4e7f-a34b-4de5e86d751c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_64619890-abd4-4177-96b2-5b5c2337aa4d" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementFrequencyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_28379181-2f1f-4e7f-a34b-4de5e86d751c" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_64619890-abd4-4177-96b2-5b5c2337aa4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_5c712cd4-239f-4b27-a448-43df34194efa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_FairValueMeasurementsRecurringMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_64619890-abd4-4177-96b2-5b5c2337aa4d" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_5c712cd4-239f-4b27-a448-43df34194efa" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_93c8cb37-6af4-41db-a238-07385192c426" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_a9aca55b-5e78-474a-86b6-59b3023ddd8c" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_93c8cb37-6af4-41db-a238-07385192c426" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_93c8cb37-6af4-41db-a238-07385192c426_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_93c8cb37-6af4-41db-a238-07385192c426" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_93c8cb37-6af4-41db-a238-07385192c426_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_8f01d064-4eb3-4258-aad5-332f87bcbb3c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_93c8cb37-6af4-41db-a238-07385192c426" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_8f01d064-4eb3-4258-aad5-332f87bcbb3c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_11a1b740-c4d3-4334-81de-c9d06ea7a07c" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_8f01d064-4eb3-4258-aad5-332f87bcbb3c" xlink:to="loc_us-gaap_InterestRateContractMember_11a1b740-c4d3-4334-81de-c9d06ea7a07c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssets_44b33069-7d5b-4383-8a78-4653e3665147" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_us-gaap_DerivativeAssets_44b33069-7d5b-4383-8a78-4653e3665147" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_adae16de-371a-47e8-95d9-885e3753b8e0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyContractAssetFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_us-gaap_ForeignCurrencyContractAssetFairValueDisclosure_adae16de-371a-47e8-95d9-885e3753b8e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_eb08ab52-eef6-45cc-8c6d-2590e78e87d0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_eb08ab52-eef6-45cc-8c6d-2590e78e87d0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_DeferredCompensationPlanAssetsFairValueDisclosure_4856af0f-b447-40c2-a6aa-5206440a78c7" xlink:href="pnr-20240331.xsd#pnr_DeferredCompensationPlanAssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_pnr_DeferredCompensationPlanAssetsFairValueDisclosure_4856af0f-b447-40c2-a6aa-5206440a78c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_c632580d-32bd-4a93-8875-5f6b837993ee" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_3bcbc9d1-104d-472b-bb12-33fb63d12caf" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_c632580d-32bd-4a93-8875-5f6b837993ee" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/ShareholdersEquityDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#ShareholdersEquityDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/ShareholdersEquityDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:href="pnr-20240331.xsd#pnr_StockholdersEquityNoteDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_StockholdersEquityNoteDisclosureTable_d2df56c4-0e8a-4f88-8ea3-b9ea384109ab" xlink:href="pnr-20240331.xsd#pnr_StockholdersEquityNoteDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_pnr_StockholdersEquityNoteDisclosureTable_d2df56c4-0e8a-4f88-8ea3-b9ea384109ab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramAxis_71fdaa4a-0369-4c78-b57d-30de3907df31" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureTable_d2df56c4-0e8a-4f88-8ea3-b9ea384109ab" xlink:to="loc_srt_ShareRepurchaseProgramAxis_71fdaa4a-0369-4c78-b57d-30de3907df31" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_71fdaa4a-0369-4c78-b57d-30de3907df31_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ShareRepurchaseProgramAxis_71fdaa4a-0369-4c78-b57d-30de3907df31" xlink:to="loc_srt_ShareRepurchaseProgramDomain_71fdaa4a-0369-4c78-b57d-30de3907df31_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ShareRepurchaseProgramDomain_981483b5-aafb-409e-8a52-00619d83b26b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ShareRepurchaseProgramDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ShareRepurchaseProgramAxis_71fdaa4a-0369-4c78-b57d-30de3907df31" xlink:to="loc_srt_ShareRepurchaseProgramDomain_981483b5-aafb-409e-8a52-00619d83b26b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_December2020ShareRepurchaseProgramMember_32da55d5-77b0-4019-8250-2861a8185303" xlink:href="pnr-20240331.xsd#pnr_December2020ShareRepurchaseProgramMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ShareRepurchaseProgramDomain_981483b5-aafb-409e-8a52-00619d83b26b" xlink:to="loc_pnr_December2020ShareRepurchaseProgramMember_32da55d5-77b0-4019-8250-2861a8185303" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_4eb2dd9a-7d69-4804-ace6-b1d9667b509b" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_4eb2dd9a-7d69-4804-ace6-b1d9667b509b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramExpirationDate_b00bfe11-0cf8-4121-bd9b-5c601daa0880" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_StockRepurchaseProgramExpirationDate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_srt_StockRepurchaseProgramExpirationDate_b00bfe11-0cf8-4121-bd9b-5c601daa0880" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_9c1b7281-de7a-4a3e-b4a4-5ce50340b940" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchasedDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_us-gaap_StockRepurchasedDuringPeriodShares_9c1b7281-de7a-4a3e-b4a4-5ce50340b940" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_c20498dd-307c-4533-a6eb-5a1f494de1aa" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_c20498dd-307c-4533-a6eb-5a1f494de1aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_3985ed88-c511-4040-a48e-6d0f04029939" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_3985ed88-c511-4040-a48e-6d0f04029939" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsPayableCurrent_aca5ef74-1d8b-42f3-85c2-452d1b76fba0" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_DividendsPayableCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_pnr_StockholdersEquityNoteDisclosureLineItems_3360defc-4bc0-473d-bc73-ec8ae8c19051" xlink:to="loc_us-gaap_DividendsPayableCurrent_aca5ef74-1d8b-42f3-85c2-452d1b76fba0" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SegmentInformationFinancialInformationbyReportableSegmentDetail" xlink:type="simple" xlink:href="pnr-20240331.xsd#SegmentInformationFinancialInformationbyReportableSegmentDetail"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SegmentInformationFinancialInformationbyReportableSegmentDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_bed3558a-2140-4e0a-888d-e1bd28490f53" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_38b4d592-3e3c-40ce-b979-26c0628c20e1" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_bed3558a-2140-4e0a-888d-e1bd28490f53" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_38b4d592-3e3c-40ce-b979-26c0628c20e1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_05280ff0-96c2-4b96-987e-4fb624b9610a" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_38b4d592-3e3c-40ce-b979-26c0628c20e1" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_05280ff0-96c2-4b96-987e-4fb624b9610a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_05280ff0-96c2-4b96-987e-4fb624b9610a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_05280ff0-96c2-4b96-987e-4fb624b9610a" xlink:to="loc_us-gaap_SegmentDomain_05280ff0-96c2-4b96-987e-4fb624b9610a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_05280ff0-96c2-4b96-987e-4fb624b9610a" xlink:to="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_IndustrialFlowTechnologiesMember_93f8c442-0784-4f7c-904d-e4984f0224d3" xlink:href="pnr-20240331.xsd#pnr_IndustrialFlowTechnologiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:to="loc_pnr_IndustrialFlowTechnologiesMember_93f8c442-0784-4f7c-904d-e4984f0224d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_WaterSolutionsMember_08d5ee0e-fa51-405b-a915-eed51da1cb61" xlink:href="pnr-20240331.xsd#pnr_WaterSolutionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:to="loc_pnr_WaterSolutionsMember_08d5ee0e-fa51-405b-a915-eed51da1cb61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateAndOtherMember_2e588fc5-85f3-46da-9345-b988c55798f2" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_CorporateAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:to="loc_us-gaap_CorporateAndOtherMember_2e588fc5-85f3-46da-9345-b988c55798f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_PoolMember_19307aa0-348a-475f-ae07-673a9c061379" xlink:href="pnr-20240331.xsd#pnr_PoolMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:to="loc_pnr_PoolMember_19307aa0-348a-475f-ae07-673a9c061379" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_FlowMember_dae574e8-9803-4120-bc7d-48159c1db171" xlink:href="pnr-20240331.xsd#pnr_FlowMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0d236f18-ed46-4c99-b210-d99214fa15c7" xlink:to="loc_pnr_FlowMember_dae574e8-9803-4120-bc7d-48159c1db171" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_38cbbb47-c4e6-4622-a7a9-255915a45dd1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_38b4d592-3e3c-40ce-b979-26c0628c20e1" xlink:to="loc_srt_ConsolidationItemsAxis_38cbbb47-c4e6-4622-a7a9-255915a45dd1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_38cbbb47-c4e6-4622-a7a9-255915a45dd1_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_38cbbb47-c4e6-4622-a7a9-255915a45dd1" xlink:to="loc_srt_ConsolidationItemsDomain_38cbbb47-c4e6-4622-a7a9-255915a45dd1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_ee3e5562-2d30-4430-a3a0-41b0650b4bf5" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_38cbbb47-c4e6-4622-a7a9-255915a45dd1" xlink:to="loc_srt_ConsolidationItemsDomain_ee3e5562-2d30-4430-a3a0-41b0650b4bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_974e5b6a-b7a0-45bd-9b1d-068c8bb5f3e5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_ee3e5562-2d30-4430-a3a0-41b0650b4bf5" xlink:to="loc_us-gaap_OperatingSegmentsMember_974e5b6a-b7a0-45bd-9b1d-068c8bb5f3e5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_d91bbb0f-8bf9-4056-a55d-618d31720d81" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_bed3558a-2140-4e0a-888d-e1bd28490f53" xlink:to="loc_us-gaap_Revenues_d91bbb0f-8bf9-4056-a55d-618d31720d81" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_68a18832-7912-4677-ad40-dd69439dc0b5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_bed3558a-2140-4e0a-888d-e1bd28490f53" xlink:to="loc_us-gaap_OperatingIncomeLoss_68a18832-7912-4677-ad40-dd69439dc0b5" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.pentair.com/role/SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails" xlink:type="simple" xlink:href="pnr-20240331.xsd#SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails"/>
  <link:definitionLink xlink:role="http://www.pentair.com/role/SegmentInformationReconciliationofOperatingProfitLossfromSegmentstoConsolidatedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_57b74634-0b65-40d0-8082-b742ec2f2dab" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_57b74634-0b65-40d0-8082-b742ec2f2dab" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_82c37ee6-a956-4227-a827-15ef75a6c9f1" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_57b74634-0b65-40d0-8082-b742ec2f2dab" xlink:to="loc_srt_ConsolidationItemsAxis_82c37ee6-a956-4227-a827-15ef75a6c9f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_82c37ee6-a956-4227-a827-15ef75a6c9f1_default" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_82c37ee6-a956-4227-a827-15ef75a6c9f1" xlink:to="loc_srt_ConsolidationItemsDomain_82c37ee6-a956-4227-a827-15ef75a6c9f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_379e187b-6a73-4a2e-92ae-acc7ba00c62e" xlink:href="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_82c37ee6-a956-4227-a827-15ef75a6c9f1" xlink:to="loc_srt_ConsolidationItemsDomain_379e187b-6a73-4a2e-92ae-acc7ba00c62e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_6ccdc0a8-c502-4e65-938a-def78efa6ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_379e187b-6a73-4a2e-92ae-acc7ba00c62e" xlink:to="loc_us-gaap_OperatingSegmentsMember_6ccdc0a8-c502-4e65-938a-def78efa6ec3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_063b572f-9896-4cbc-8601-7b656ff38a27" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_379e187b-6a73-4a2e-92ae-acc7ba00c62e" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_063b572f-9896-4cbc-8601-7b656ff38a27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_09328772-c6c8-48d5-ad1d-2ba9e6d73301" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_OperatingIncomeLoss_09328772-c6c8-48d5-ad1d-2ba9e6d73301" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_5d1a55ec-ad3a-4efa-b812-e95a8f4b2b5e" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_AssetImpairmentCharges_5d1a55ec-ad3a-4efa-b812-e95a8f4b2b5e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_RestructuringandOtherCosts_e9e41eae-7e63-4754-8398-791da43e5c04" xlink:href="pnr-20240331.xsd#pnr_RestructuringandOtherCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_pnr_RestructuringandOtherCosts_e9e41eae-7e63-4754-8398-791da43e5c04" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_TransformationCosts_46be5bc4-d60f-4d64-b1a2-04601b627301" xlink:href="pnr-20240331.xsd#pnr_TransformationCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_pnr_TransformationCosts_46be5bc4-d60f-4d64-b1a2-04601b627301" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_f12035de-5435-4d4f-93d6-03ae0e37ea23" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_f12035de-5435-4d4f-93d6-03ae0e37ea23" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_pnr_LegalAccrualAdjustments_fe0d593f-d34b-43ba-b85b-1a4dd89dd9f3" xlink:href="pnr-20240331.xsd#pnr_LegalAccrualAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_pnr_LegalAccrualAdjustments_fe0d593f-d34b-43ba-b85b-1a4dd89dd9f3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeExpenseNet_919fb2bf-5a5c-4045-a28d-5d0ccda4e625" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_InterestIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_InterestIncomeExpenseNet_919fb2bf-5a5c-4045-a28d-5d0ccda4e625" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_bc6b8851-4b66-405c-9bd8-39999c3613bd" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_bc6b8851-4b66-405c-9bd8-39999c3613bd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2c8abcbd-6fa7-4a9e-af9c-4a6bd10db4c5" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_99b38692-86ff-4918-975e-c2e3ccde4319" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_2c8abcbd-6fa7-4a9e-af9c-4a6bd10db4c5" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd#AwardTypeOnly"/>
  <link:definitionLink xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_StockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_StockOptionMember" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember" xlink:href="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaap_PerformanceSharesMember" xlink:type="arc" order="5"/>
  </link:definitionLink>
</link:linkbase>
