Minot Water Hardness & Quality Report (2026)

Minot, North Dakota, the Ward County seat — the fourth-largest city in North Dakota, a major North Dakota agricultural and energy hub, home of Minot Air Force Base (a major USAF nuclear missile wing) and Minot State University, nicknamed the 'Magic City' (for its rapid growth during the Great Northern Railway construction), and a major North Dakota oil patch service city — draws its municipal water supply from the Souris River via the City of Minot Water Treatment Plant. Water hardness in Minot measures 307 mg/L — classified as very hard.

Minot's very hard supply reflects the Souris River's concentrated Northern Great Plains calcareous and evaporitic geology. The Souris River above Minot drains the Saskatchewan–Manitoba Prairie and the North Dakota Missouri Coteau: Cretaceous Pierre Shale (calcareous marine shale of the Western Interior Seaway — extremely widespread, highly calcareous dark marine shale); Tertiary Fort Union Formation (calcareous freshwater limestone, coal, and mudstone — calcareous Paleocene lacustrine terrain); the Wisconsin Age calcareous glacial drift of the Missouri Coteau (calcareous till derived from Cretaceous and Tertiary calcareous formations, leached into the Prairie potholes — pothole lake recharge is the Souris Valley's major runoff source, highly concentrated by evaporation). The Prairie pothole evaporative concentration produces the very hard 307 mg/L.

At 307 mg/L, Minot residents face severe hard water challenges. Scale deposits form very rapidly on all fixtures and appliances — weekly descaling and appliance protection measures are strongly recommended. City of Minot Water Treatment Plant consistently delivers water meeting all North Dakota DEQ and EPA Safe Drinking Water Act requirements.