Tiffin Water Hardness & Quality Report (2026)

Tiffin, Ohio, in Seneca County — the Seneca County seat adjacent to Fostoria and Fremont on the Sandusky River in north-central Ohio — receives its municipal water from the Tiffin Water Division, drawing from the Sandusky River at the Tiffin intake in Seneca County.

The hard 165 mg/L hardness and TDS of 328 mg/L reflect the north-central Ohio Sandusky River's Silurian-Devonian carbonate character — similar to other north Ohio river supply communities (Findlay OH: 180 mg/L — Blanchard River, also Silurian Niagara Dolomite). The Sandusky River drains the Ohio Till Plain — Silurian Niagara Dolomite and Salina Group (the dominant north Ohio carbonate platform, source of the Niagara Falls dolomite), Devonian Columbus Limestone (high-purity calcite — major hardness contributor), and calcareous Pleistocene Woodfordian till (ground-up dolomite and limestone).

At 165 mg/L, Tiffin's water is hard — scale builds steadily in kettles and appliances, dishwashers benefit from rinse aid, and water heaters should be descaled annually. Monthly descaling is recommended. The PFAS level of 6.4 ppt warrants a certified drinking water filter — the Seneca County industrial corridor, the Sandusky River agricultural PFAS runoff (north Ohio corn belt), and the north Ohio-Lake Erie PFAS background contribute to Tiffin's readings.