Willow Grove Water Hardness & Quality Report (2026)

Willow Grove, Pennsylvania, in Montgomery County — an unincorporated Montgomery County community adjacent to Horsham and Hatboro in north Montgomery County — receives its municipal water from the North Penn Water Authority (NPWA) or a local authority, drawing from the Perkiomen Creek (North Branch, Montgomery County) or local reservoirs through the north Montgomery County treatment system.

The moderately hard 100.5 mg/L hardness and TDS of 164.5 mg/L are consistent with the North Penn Water Authority north Montgomery County communities — harder than the Philadelphia Schuylkill-fed neighborhoods (Strawberry Mansion: 95.5 mg/L) due to the Perkiomen Creek's concentrated Cambrian Allentown Dolomite and Ordovician Jacksonburg Limestone exposure in the north Montgomery watershed. The Perkiomen Creek drainage crosses Cambrian Allentown Dolomite (high purity dolomite — primary hardness contributor), Ordovician Jacksonburg Limestone (calcareous), and Precambrian Reading Prong Granite (insoluble).

At 100.5 mg/L, Willow Grove's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling is appropriate. The PFAS level of 5.0 ppt warrants a certified drinking water filter — Naval Air Station Joint Reserve Base Willow Grove (Montgomery County — AFFF, decommissioned base with a documented PFAS plume directly under Willow Grove) is the primary PFAS source for this community.