Missoula Water Hardness & Quality Report (2026)

Missoula Water, operated by the City of Missoula, serves approximately 75,000 residents in Missoula County, Montana. The utility sources water primarily from the W.W. Clark Water Treatment Plant, which draws directly from the Clark Fork River, supplemented by groundwater from wells in the Rattlesnake Valley and other local aquifers. There are no known lead service lines city-wide, though private plumbing may contribute trace metals. The W.W. Clark Plant applies coagulation, sedimentation, filtration, and chloramination before water enters the distribution network.

The Clark Fork River watershed spans the Northern Rockies, fed by snowmelt from the Bitterroot and Sapphire Mountains. Water chemistry is shaped by glacial till, alluvial gravels, and limestone outcrops from Paleozoic and Mesozoic eras. Quaternary alluvial deposits overlie older Tertiary and Cretaceous sedimentary rocks including sandstones and limestones that contribute dissolved calcium and magnesium ions as groundwater percolates through these formations. This geology consistently yields a mineralized, hard supply characteristic of the Northern Rocky Mountains, with seasonal runoff influencing variability.

Hard water from Missoula's supply promotes limescale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan. Boilers and fixtures show visible deposits, increasing energy costs by up to 20–30%. Regular vinegar descaling, installing drain screens, and annual heater flushes help; a whole-house softener is recommended for optimal appliance protection and soap efficiency. The 2024 Consumer Confidence Report confirms full compliance with Safe Drinking Water Act standards, including lead at a 90th percentile of 0.005 mg/L — well below the action level. pH averages 7.5–8.0; no PFAS data reported, with primary concerns being naturally occurring minerals.