Findlay Water Hardness & Quality Report (2026)

Findlay, Ohio, the Hancock County seat — a major northwest Ohio city historically known as the 'Flag City USA' (Findlay displays an extraordinary number of US flags throughout the city year-round), home of the University of Findlay (a private Ohio university notable for equine studies, pharmacy, and environmental science), Marathon Petroleum Corporation headquarters (one of the largest US petroleum refining companies), and a major northwest Ohio manufacturing and petroleum industry community — draws its municipal water supply from the Findlay Arch groundwater system via the City of Findlay Water Division. Water hardness in Findlay measures 204.5 mg/L — classified as hard.

Findlay's hard supply reflects the northwest Ohio Findlay Arch's highly calcareous dolomite and limestone geology. The Findlay Arch — a major subsurface geological arch structure — exposes: the Silurian Lockport Dolomite (the highly calcareous dolomite of the Niagara Group, the same calcareous formation underlying Niagara Falls); the Devonian Columbus Limestone and Delaware Limestone (highly calcareous marine limestone of the Ohio Devonian sequence); and the Silurian Salina Group evaporite (highly calcareous–gypsiferous evaporite of the Findlay Arch zone). The Findlay Arch's pure calcareous dolomite and limestone karst produces the hard 204.5 mg/L.

At 204.5 mg/L, Findlay residents face regular hard water challenges. Monthly descaling with citric acid solution is standard maintenance. City of Findlay Water Division consistently delivers water meeting all Ohio EPA and federal EPA Safe Drinking Water Act requirements.