Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2020	Jan. 31, 2021
Document And Entity Information [Abstract]
Document Fiscal Period Focus	Q1
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2021
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 Current Reporting Status	Yes
Entity Emerging Growth Company	false
Amendment Flag	false
Entity Common Stock, Shares Outstanding		158,435,893
Entity Small Business	false
Trading Symbol	MWA
Title of 12(b) Security	$0.01 par value common stock