Sunset Park Water Hardness & Quality Report (2026)

Sunset Park, a Brooklyn neighborhood in Kings County, New York City, receives its municipal water supply from the New York City Department of Environmental Protection (NYC DEP), drawing from the combined Catskill–Delaware watershed system — nine major reservoirs in the Catskill Mountains and Delaware River headwaters of Ulster, Delaware, Schoharie, and Greene Counties in the Catskill uplands of upstate New York. The Catskill–Delaware system is one of the largest unfiltered surface water supplies in the world, with water gravity-fed by aqueduct to the Hillview Reservoir in Yonkers and distributed throughout all five New York City boroughs. Water hardness in Sunset Park measures 158 mg/L — classified as hard.

Sunset Park's hard supply — notably higher than the inherently soft Catskill source water (typically 20–40 mg/L in reservoirs) — reflects extensive NYC distribution system infrastructure aging and pipe interactions throughout the vast underground distribution network serving Brooklyn. The source water from Catskill Mountains Devonian and Silurian sandstone and shale (the Catskill Clastic Wedge, Devonian Catskill Formation, and Silurian Bloomsburg Formation) is naturally very soft; however, decades of contact with the cast-iron and ductile iron distribution mains throughout Brooklyn's densely-built distribution network, combined with blending with slightly harder Croton watershed water, elevates measured hardness significantly at Brooklyn tap points.

At 158 mg/L, Sunset Park residents encounter hard water challenges typical of Brooklyn's water distribution. Scale deposits form on faucet aerators and showerheads — monthly cleaning with citric acid solution is beneficial. Dishwashers produce better glassware results with rinse-aid. NYC DEP consistently delivers water meeting all NYSDOH and EPA Safe Drinking Water Act requirements.