Scarsdale Water Hardness & Quality Report (2026)

Scarsdale, New York, in Westchester County — a Westchester County town adjacent to Eastchester and White Plains in the south Westchester County corridor, an affluent New York City suburb — receives its municipal water from Westchester Joint Water Works (WJWW) or New York City DEP, drawing from the Kensico Reservoir (Bronx River-Rye Pond watershed, Westchester County) or the Croton-Catskill system.

The moderately hard 164.5 mg/L hardness and TDS of 419.4 mg/L are harder than the typical New York City Catskill-Delaware supply (NYC: 20-80 mg/L), suggesting Scarsdale receives a Westchester-local supply rather than the full NYC Catskill system. The Westchester local supply draws from the Bronx River watershed and Kensico Reservoir — influenced by the Ordovician Inwood Marble (calcareous crystalline marble beneath Westchester), the Triassic Palisades diabase (slightly calcareous), and the Harlem-Bronx River calcareous terrane.

At 164.5 mg/L, Scarsdale's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and bathroom fixtures develop calcium deposits. Quarterly descaling is appropriate. The PFAS level of 7.9 ppt warrants a certified drinking water filter — the Stewart Air National Guard Base (Orange County — AFFF in the Hudson-Bronx watershed), the Westchester County suburban industrial corridor, and the lower Hudson Valley PFAS complex contribute to Scarsdale's elevated readings.