Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Nov. 10, 2020	Mar. 31, 2020	Sep. 30, 2019
Document Information [Line Items]
Document Fiscal Period Focus	FY
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Entity Well-known Seasoned Issuer	Yes
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-K
Property, plant and equipment, net	$ 253.8			$ 217.1
Intangible Assets, Net (Including Goodwill)	$ 508.7			$ 529.4
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Amendment Flag	false
Entity Common Stock, Shares Outstanding		158,102,357
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Public Float			$ 1,248.3