East Massapequa Water Hardness & Quality Report (2026)

East Massapequa, New York, in Nassau County — an unincorporated Nassau County community adjacent to Massapequa and Seaford, on the South Shore of Long Island near South Oyster Bay — receives its municipal water from the Nassau County DPW or the Massapequa Water District, drawing from the Magothy Aquifer through production wells in the south Nassau County area.

The moderately hard 172.5 mg/L hardness and elevated TDS of 453.6 mg/L are consistent with the south Nassau County Magothy Aquifer's deeper, more mineralized character — harder than the Mineola central Nassau supply (95 mg/L, TDS 173). The south Nassau coastal zone wells access the deeper Cretaceous Magothy Formation — an extensive multi-layered sand aquifer that has longer water residence time and greater contact with calcareous and glauconitic Cretaceous marine sediment. This produces harder, higher-TDS water in the south shore zone than the shallower Upper Glacial Aquifer wells.

At 172.5 mg/L, East Massapequa'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 8.2 ppt warrants a certified drinking water filter — the Grumman Bethpage PFAS plume (Nassau County — the Bethpage PFAS contamination plume extends south toward the Massapequa water district wells), Mitchel Field legacy, and the south Nassau industrial-aviation PFAS complex contribute to East Massapequa's elevated readings.