Williston Water Hardness & Quality Report (2026)

Williston, North Dakota, the Williams County seat — a major northwest North Dakota Bakken oil boom city (Williston is the Williams County seat — one of the most economically transformed cities in the United States in the early 21st century; Williston is at the heart of the Bakken Shale formation (one of the most important oil-producing formations in the United States — the Bakken Shale underlies a large portion of western North Dakota and eastern Montana; the Bakken oil boom of the late 2000s and 2010s transformed Williston from a small agricultural city of roughly 12,000 to a boomtown of nearly 30,000 at its peak, with worker shortages, extreme housing costs, and rapid infrastructure expansion; the Bakken boom made North Dakota briefly the second-largest oil-producing state in the United States)); Williston serves as the economic hub for the entire northwest North Dakota and northeast Montana Bakken region, a diverse Williams County community with a significant Native American (Three Affiliated Tribes — Mandan, Hidatsa, Arikara), oil and gas worker, and increasingly permanent family population, adjacent to the Fort Berthold Indian Reservation corridor — draws its municipal water supply via the City of Williston Water Division. Water hardness in Williston measures 286.5 mg/L — classified as very hard.

Williston's very hard supply reflects the northwest North Dakota Williams County Williston Basin closed-basin aquifer's highly calcareous character. The Williston Basin Aquifer draws from Cretaceous calcareous evaporite (calcareous). Very limited softening produces the very hard 286.5 mg/L.

At 286.5 mg/L, Williston residents face significant hard water challenges. Regular water softeners and descaling are strongly recommended. City of Williston Water Division consistently delivers water meeting all North Dakota DEQ and EPA Safe Drinking Water Act requirements.