Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Jan. 24, 2021	Jun. 26, 2020
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Entity File Number	001-11499
Entity Registrant Name	WATTS WATER TECHNOLOGIES INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2916536
Entity Address, Address Line One	815 Chestnut Street
Entity Address, City or Town	North Andover
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01845
City Area Code	978
Local Phone Number	688-1811
Title of 12(b) Security	Class A common stock, par value $0.10 per share
Trading Symbol	WTS
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
ICFR Auditor Attestation Flag	true
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2,137,251,957
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0000795403
Amendment Flag	false
Class A
Entity Common Stock, Shares Outstanding		27,470,911
Class B
Entity Common Stock, Shares Outstanding		6,144,290