Great Kills Water Hardness & Quality Report (2026)

Great Kills, New York, in Richmond County (Staten Island) — a historic southern Staten Island neighborhood with the Great Kills Harbor marina and the Gateway National Recreation Area's Great Kills Unit on Lower New York Bay — receives its municipal water from the New York City Department of Environmental Protection (NYC DEP), which draws from the Catskill-Delaware Watershed system serving all five New York City boroughs. Great Kills is served through Staten Island's NYC DEP distribution network fed by the Delaware Aqueduct.

The moderately soft 86.5 mg/L hardness and TDS of 150.5 mg/L are slightly above the purest Catskill-Delaware supply baseline (~65–75 mg/L seen in well-characterized Catskill zones like Melrose in the Bronx), reflecting the additional mineral contributions that accumulate in Staten Island's distribution system — a borough served through aging pipes and the longest transmission pathway from the Catskill reservoir system. NYC DEP's Catskill-Delaware water originates from the Devonian and Silurian shale and sandstone highlands of the Catskill Mountains — inherently soft, low-carbonate terrain. Staten Island's supply travels through the Richmond Tunnel from New Jersey and the Richmond Water Works, and the extended transit path and older infrastructure contribute modest additional mineral content compared to Manhattan or Bronx zones closer to the DEP treatment plants.

At 86.5 mg/L, Great Kills' water is moderately soft — comfortable for household use. Scale forms slowly over many months, soap lathers well, and the dishwasher produces clean results. Semi-annual descaling of heating appliances is adequate. The PFAS level of 4.2 ppt is moderate for New York City — the Linden Kill and Fresh Kills sites on Staten Island, the borough's proximity to the New Jersey PFAS industrial corridor, and the broader NYC metropolitan PFAS background contribute to the Staten Island distribution zone's PFAS profile.