Butte Water Hardness & Quality Report (2026)

Butte, Montana, the Silver Bow County seat — a historic mining city (Butte was once called 'The Richest Hill on Earth' — the copper mines of Butte produced more copper than any other single location in the world during the late 19th and early 20th centuries, making Butte one of the most important industrial cities in the American West), home of the Berkeley Pit (one of the largest open-pit copper mines in North America — now a Superfund site containing billions of gallons of toxic acidic water, a notorious environmental legacy of mining history), a diverse Silver Bow County community with a significant Irish-American, Cornish-American, and Finnish-American heritage population (Butte attracted massive immigrant mining labor from Ireland, Wales, and Scandinavia), and a National Historic Landmark District (Uptown Butte is a remarkably preserved example of late 19th century mining boomtown architecture) — draws its municipal water supply from the Clark Fork headwaters via the City of Butte-Silver Bow Water Division. Water hardness in Butte measures 56 mg/L — classified as moderately soft.

Butte's soft supply reflects the Silver Bow County Precambrian Belt Supergroup watershed's calcareous-poor geology. The Silver Bow Creek watershed at Butte–Silver Bow County drains: the Precambrian Belt Supergroup quartzite and argillite (calcareous-poor — the highly resistant Proterozoic sedimentary belt; the Helena and Newland Formations' dolomitic members contribute minimal dissolved calcium). City of Butte-Silver Bow Water Division treatment produces the soft 56 mg/L.

With hardness at 56 mg/L, Butte residents enjoy moderately soft water. City of Butte-Silver Bow consistently delivers water meeting all Montana DEQ and EPA Safe Drinking Water Act requirements.