Hamilton Water Hardness & Quality Report (2026)

Hamilton, Ohio, the Butler County seat on the Great Miami River between Cincinnati and Dayton — a historic paper and manufacturing city known as Ohio's 'City of Sculpture' for its extensive public art collection — draws its municipal water supply from the Great Miami River via the City of Hamilton Water Treatment Plant, treating Great Miami River water for Hamilton. The Great Miami River above Hamilton drains the southwestern Ohio Silurian and Ordovician carbonate terrain. Water hardness in Hamilton measures 177.5 mg/L — classified as hard.

Hamilton's hard supply reflects the Great Miami River basin's exceptional Silurian–Ordovician carbonate geology in southwest Ohio. The Great Miami River above Hamilton drains: the Silurian Lockport Dolomite (reactive dolomite — the same formation underlying Niagara Falls and the Ohio–Indiana Silurian carbonate platform); the Silurian Salina Formation (evaporitic dolomite with gypsum interbeds — significant dissolved calcium and sulfate contributor); and the Ordovician Trenton Limestone and Black River Limestone (highly reactive calcareous limestone). Southwest Ohio's Silurian carbonate bedrock is among the most calcareous in the Midwest — the Great Miami River in Butler County drains a classic Ohio limestone county terrain, producing the hard 177.5 mg/L supply.

At 177.5 mg/L, Hamilton residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, and appliances within weeks — monthly descaling with citric acid solution is standard maintenance. City of Hamilton Water Treatment Plant consistently delivers water meeting all Ohio EPA and federal EPA Safe Drinking Water Act requirements.