Bismarck Water Hardness & Quality Report (2026)

Bismarck, North Dakota, the state capital in Burleigh County on the Missouri River — the geographic center of the North American continent — draws its municipal water supply from the Missouri River (specifically from Lake Oahe, the massive Corps of Engineers reservoir created by Garrison Dam upstream in McLean County) via the City of Bismarck Water Distribution Division, treating Missouri River water at the Bismarck Water Treatment Plant. Lake Oahe is one of the largest reservoirs in the United States. Water hardness in Bismarck reaches 316 mg/L — classified as very hard.

Bismarck's very hard supply reflects the upper Missouri River's accumulated mineral load in North Dakota. The Missouri River at the Bismarck–Lake Oahe reach drains the Northern Great Plains of Montana and Wyoming — collecting: the Cretaceous Pierre Shale (a massive calcareous marine formation covering most of the Dakotas — the predominant bedrock beneath the Missouri River Valley in North Dakota, releasing calcium and bicarbonate readily); the Cretaceous Niobrara Chalk (calcareous chalk of the Upper Missouri Basin); the Paleocene Fort Union Formation (coal-bearing calcareous mudstone — significant ion exchange contribution); and Quaternary glacial till and loess of the Missouri Coteau (calcareous drift from the Laurentide Ice Sheet grinding Pierre Shale). North Dakota's Missouri River municipalities consistently produce very hard water reflecting the Pierre Shale's dominance.

At 316 mg/L, Bismarck residents face significant hard water challenges. Scale deposits form rapidly on faucet aerators, showerheads, shower glass, and tile — monthly descaling with citric acid solution is essential maintenance. Dishwashers require rinse-aid, and water heaters need annual inspection. City of Bismarck Water Distribution Division consistently delivers water meeting all North Dakota DOH and EPA Safe Drinking Water Act requirements.