Butte Water Hardness & Quality Report (2026)

The Butte-Silver Bow Water Department serves approximately 33,000 residents in Butte and surrounding Silver Bow County, Montana. The utility operates three primary water sources — the Big Hole River, South Fork Reservoir, and Moulton Reservoir — supplemented by Basin Creek. Water is treated at centralized facilities before distribution to the service area, with the utility maintaining compliance with federal and state drinking water standards.

The Butte water supply originates from the Big Hole River watershed and associated reservoirs in southwestern Montana's Rocky Mountain region. The underlying geology comprises mineralized rock formations typical of the Northern Rockies, including carbonate and sulfate-bearing strata. These formations impart moderate mineral content — particularly calcium and sulfate ions — resulting in moderately hard water that reflects the region's natural hydrogeochemistry.

At moderately hard levels, residents may experience minor scaling in hot water heaters and appliances, spotting on glassware, and reduced soap effectiveness; routine maintenance is typically sufficient. A water softener is optional rather than essential, though softening can extend appliance life. Butte's water has historically contained multiple contaminants above EPA health guidelines, including arsenic, bromodichloromethane, chloroform, dichloroacetic acid, radiological contaminants, trihalomethanes, and trichloroacetic acid. In May 2026, a cross-connection incident between mining operations and the municipal supply prompted a precautionary do-not-consume order; testing revealed elevated calcium and sulfate but no confirmed contamination beyond mine property. Consult the annual Consumer Confidence Report or contact the utility at 406-497-6440 for current water quality data.