Yonkers Water Hardness & Quality Report (2026)

Yonkers, New York receives its drinking water from Westchester Joint Water Works, supplied by the New York City Department of Environmental Protection (NYC DEP) Croton Watershed system and the city's own Hillview Reservoir connections. The New Croton Reservoir in Westchester County serves as the primary storage, collecting water from the 375-square-mile Croton watershed in Westchester County. The Croton Water Filtration Plant — opened in 2015 as New York City's newest major treatment facility — processes all Croton system water before distribution to Yonkers and surrounding Westchester communities. Water hardness in Yonkers measures 95.5 mg/L — classified as moderately soft.

The moderate hardness of Yonkers' Croton supply reflects the geological diversity of the Westchester watershed. The Croton watershed drains a complex mix of terrain: Precambrian Manhattan Schist and Fordham Gneiss (calcium-poor metamorphic basement), Cambrian and Ordovician marble and calcareous schist along the limestone belt through central Westchester, and Triassic rift sediments in parts of the lower watershed. The limestone and marble zones contribute moderate dissolved calcium and bicarbonate, while the dominant metamorphic terrain limits overall hardness, producing a blended supply in the moderately soft range.

At 95.5 mg/L, Yonkers residents experience moderate scale accumulation over time. Faucet aerators and showerheads develop light deposits after several months — quarterly cleaning with vinegar or citric acid keeps them in good working order. Kettles accumulate a minor mineral ring that benefits from occasional descaling. Dishwashers produce clean results with standard rinse-aid, and hot water systems experience modest long-term scale build-up without requiring urgent intervention. NYC DEP and Westchester Water Works consistently deliver water meeting all federal Safe Drinking Water Act requirements in the Yonkers distribution area.