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Document and Entity Information - USD ($)
 6 Months Ended
Mar. 31, 2018
Apr. 30, 2018
Document And Entity Information [Abstract]    
Document Fiscal Period Focus Q2  
Document Period End Date Mar. 31, 2018  
Document Fiscal Year Focus 2018  
Entity Well-known Seasoned Issuer No  
Entity Registrant Name Mueller Water Products, Inc.  
Entity Central Index Key 0001350593  
Current Fiscal Year End Date --09-30  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Entity Voluntary Filers No  
Entity Current Reporting Status Yes  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   158,101,489
Entity Public Float $ 1,702,208,205