Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 27, 2019	Jun. 29, 2018
Entity Registrant Name	WATTS WATER TECHNOLOGIES INC
Entity Central Index Key	0000795403
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 2,164,731,408
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Class A
Entity Common Stock, Shares Outstanding		27,623,445
Class B
Entity Common Stock, Shares Outstanding		6,329,290