<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>101</ContextCount>
  <ElementCount>273</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>35</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Document - Cover Page Document</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/CoverPageDocument</Role>
      <ShortName>Cover Page Document</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - Consolidated Statements Of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedStatementsOfOperations</Role>
      <ShortName>Consolidated Statements Of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - Statement - Consolidated Statement of Comprehensive Income Statement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedStatementofComprehensiveIncomeStatement</Role>
      <ShortName>Consolidated Statement of Comprehensive Income Statement</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - Statement - Consolidated Statement Of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedStatementOfStockholdersEquity</Role>
      <ShortName>Consolidated Statement Of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Statement - Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements Of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - Disclosure - Organization</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/Organization</Role>
      <ShortName>Organization</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - Disclosure - Revenue from Contracts with Customers (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RevenuefromContractswithCustomersNotes</Role>
      <ShortName>Revenue from Contracts with Customers (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Borrowing Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/BorrowingArrangements</Role>
      <ShortName>Borrowing Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RetirementPlans</Role>
      <ShortName>Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Stock-based Compensation Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlans</Role>
      <ShortName>Stock-based Compensation Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Supplemental Balance Sheet Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformation</Role>
      <ShortName>Supplemental Balance Sheet Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/AccumulatedOtherComprehensiveLoss</Role>
      <ShortName>Accumulated Other Comprehensive Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9954471 - Disclosure - Organization Restructuring Rollforward (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/OrganizationRestructuringRollforwardTables</Role>
      <ShortName>Organization Restructuring Rollforward (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9954472 - Disclosure - Revenue from Contracts with Customers (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RevenuefromContractswithCustomersTables</Role>
      <ShortName>Revenue from Contracts with Customers (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/RevenuefromContractswithCustomersNotes</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9954473 - Disclosure - Income Taxes Rate Reconciliation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/IncomeTaxesRateReconciliationTables</Role>
      <ShortName>Income Taxes Rate Reconciliation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9954474 - Disclosure - Borrowing Arrangements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/BorrowingArrangementsTables</Role>
      <ShortName>Borrowing Arrangements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/BorrowingArrangements</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9954475 - Disclosure - Retirement Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RetirementPlansTables</Role>
      <ShortName>Retirement Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/RetirementPlans</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9954476 - Disclosure - Stock-based Compensation Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlansTables</Role>
      <ShortName>Stock-based Compensation Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlans</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9954477 - Disclosure - Supplemental Balance Sheet Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationTables</Role>
      <ShortName>Supplemental Balance Sheet Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9954478 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SegmentInformation</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9954479 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/AccumulatedOtherComprehensiveLossTables</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/AccumulatedOtherComprehensiveLoss</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9954480 - Disclosure - Organization (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/OrganizationNarrativeDetails</Role>
      <ShortName>Organization (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/OrganizationRestructuringRollforwardTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9954481 - Disclosure - Organization Restructuring (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/OrganizationRestructuringDetails</Role>
      <ShortName>Organization Restructuring (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/OrganizationRestructuringRollforwardTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9954482 - Disclosure - Revenue from Contracts with Customers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RevenuefromContractswithCustomersDetails</Role>
      <ShortName>Revenue from Contracts with Customers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/RevenuefromContractswithCustomersTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9954483 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/IncomeTaxesRateReconciliationTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9954484 - Disclosure - Income Taxes Income Tax Rate Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/IncomeTaxesIncomeTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes Income Tax Rate Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9954485 - Disclosure - Borrowing Arrangements (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/BorrowingArrangementsNarrativeDetails</Role>
      <ShortName>Borrowing Arrangements (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/BorrowingArrangementsTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9954486 - Disclosure - Borrowing Arrangements (Components Of Long-Term Debt) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/BorrowingArrangementsComponentsOfLongTermDebtDetails</Role>
      <ShortName>Borrowing Arrangements (Components Of Long-Term Debt) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/BorrowingArrangementsTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9954487 - Disclosure - Retirement Plans (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RetirementPlansNarrativeDetails</Role>
      <ShortName>Retirement Plans (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/RetirementPlansTables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9954488 - Disclosure - Retirement Plans (Net Periodic Benefit Cost) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/RetirementPlansNetPeriodicBenefitCostDetails</Role>
      <ShortName>Retirement Plans (Net Periodic Benefit Cost) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/RetirementPlansTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9954489 - Disclosure - Stock-based Compensation Plans (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlansNarrativeDetails</Role>
      <ShortName>Stock-based Compensation Plans (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlansTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9954490 - Disclosure - Stock-based Compensation Plans Grants Table (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/StockbasedCompensationPlansGrantsTableDetails</Role>
      <ShortName>Stock-based Compensation Plans Grants Table (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9954491 - Disclosure - Supplemental Balance Sheet Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationScheduleOfSelectedSupplementalBalanceSheetInformationDetails</Role>
      <ShortName>Supplemental Balance Sheet Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9954492 - Disclosure - Supplemental Balance Sheet Information (Schedule of Accrued Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationScheduleofAccruedLiabilitiesDetails</Role>
      <ShortName>Supplemental Balance Sheet Information (Schedule of Accrued Liabilities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9954493 - Disclosure - Supplemental Balance Sheet Information (Goodwill) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationGoodwillDetails</Role>
      <ShortName>Supplemental Balance Sheet Information (Goodwill) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SupplementalBalanceSheetInformationTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9954494 - Disclosure - Segment Information (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SegmentInformationNarrativeDetails</Role>
      <ShortName>Segment Information (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SegmentInformationTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9954495 - Disclosure - Segment Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SegmentInformationScheduleOfSelectedSupplementalBalanceSheetInformationDetails</Role>
      <ShortName>Segment Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SegmentInformationTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9954496 - Disclosure - Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/AccumulatedOtherComprehensiveLossScheduleOfAccumulatedOtherComprehensiveLossDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/AccumulatedOtherComprehensiveLossTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="mwa-20231231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9954497 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.muellerwaterproducts.com/role/SubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.muellerwaterproducts.com/role/SubsequentEvents</ParentRole>
      <Position>48</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="mwa-20231231.htm">mwa-20231231.htm</File>
    <File>mwa-20231231.xsd</File>
    <File>mwa-20231231_cal.xml</File>
    <File>mwa-20231231_def.xml</File>
    <File>mwa-20231231_lab.xml</File>
    <File>mwa-20231231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="559">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
