Passaic Water Hardness & Quality Report (2026)

Passaic, New Jersey, in Passaic County on the Passaic River — a densely populated city with one of New Jersey's most diverse immigrant populations — draws its municipal water supply from the Passaic River (Dundee Lake impoundment at the Great Falls of the Passaic) via the Passaic Valley Water Commission (PVWC), treating Passaic River water for Passaic and surrounding communities in the Passaic Valley. The Passaic River at Passaic/Clifton has emerged from the Great Passaic Swamp (the glacial lake bed of post-glacial Lake Passaic). Water hardness in Passaic measures 140 mg/L — classified as moderately hard.

Passaic's moderate hardness reflects the Passaic River watershed's New Jersey Piedmont geology. The Passaic River drains: the New Jersey Highlands (Precambrian Reading Prong gneiss and quartzite — soft calcium-poor contribution); the Newark Basin floor (Jurassic Passaic Formation and Stockton Formation — red arkosic sandstone and mudstone with some calcareous binder); and the Watchung Basalt ridges (Jurassic Holyoke and Orange Mountain Basalt — calcium-poor volcanic rock). The calcareous cementation in the Jurassic Newark Basin arkosic sandstone contributes moderate dissolved calcium to the Passaic River, while the calcareous glacial outwash in the former Lake Passaic basin floor also adds mineral content.

At 140 mg/L, Passaic residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. Passaic Valley Water Commission consistently delivers water meeting all New Jersey DEP and EPA Safe Drinking Water Act requirements.