Westchester Joint Water Works (WJWW) is a nonprofit public benefit corporation formed in 1927 with a duty to act in the best interests of the public it serves.

WJWW is composed of three member municipalities: the Village of Mamaroneck, the Town of Mamaroneck, and the Town/Village of Harrison. ​

WJWW supplies water to its member municipalities and to portions of the cities of Rye and New Rochelle, serving 59,629 consumers through 14,682 service connections.

WJWW also provides water on a wholesale basis to the Village of Larchmont and Suez Water Westchester, which sells water to the City of Rye, Village of Rye Brook and Village of Port Chester, which collectively represent approximately another 60,000 consumers.