Hollis Water Hardness & Quality Report (2026)

Hollis, New York, in Queens County — a southeastern Queens neighborhood adjacent to Jamaica and St. Albans, a predominantly African American residential community in southeastern Queens — receives its municipal water from NYC DEP, which delivers primarily Catskill-Delaware Reservoir supply to Queens through the NYC tunnel system. However, the Hollis neighborhood is in close proximity to the Jamaica Aquifer zone in southeastern Queens, where NYC historically supplemented Catskill-Delaware supply with local Cretaceous Magothy Formation and Lloyd Sand groundwater wells.

The moderately hard 168 mg/L hardness and elevated TDS of 434.2 mg/L are substantially harder than Cambria Heights (72 mg/L, TDS 114) just a few miles away in the same Queens borough — suggesting this supply zone may blend Catskill-Delaware reservoir water with Jamaica groundwater supply. The Jamaica Aquifer (the Cretaceous Magothy Formation and the Lloyd Sand) in southeastern Queens contains groundwater that has been in contact with Cretaceous coastal plain calcareous sediment for extended periods, producing harder water than the direct Catskill supply. NYC DEP historically operated wells in the Jamaica zone, and blending effects or localized hardness from old cast iron distribution pipes could explain the harder Hollis reading.

At 168 mg/L, Hollis'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 8.0 ppt warrants a certified drinking water filter — the Jamaica Bay industrial corridor, JFK International Airport (a major AFFF user on Jamaica Bay), and the southeastern Queens industrial legacy contribute to the higher PFAS reading in this Queens zone.