Billings Water Hardness & Quality Report (2026)

Billings, Montana — the largest city in Montana — draws its municipal water supply directly from the Yellowstone River via the City of Billings Public Works Water Division, operating an intake and water treatment facility along the Yellowstone River in Yellowstone County. The Yellowstone River originates in Yellowstone National Park, flowing through the Absaroka and Beartooth ranges before crossing the Billings area. It is one of the longest undammed rivers in the United States. Water hardness measures 60 mg/L — classified as moderately soft.

Billings' moderately soft supply reflects the volcanic and Precambrian crystalline geology of the upper Yellowstone River watershed. The Yellowstone River headwaters drain: Yellowstone National Park — geologically dominated by Quaternary Yellowstone rhyolite and basalt, Tertiary andesite, and the Eocene Absaroka Volcanic Supergroup (the massive volcanic arc sequence forming the Absaroka Mountains) — all low-calcium volcanic terrain; and the Beartooth Plateau — underlain by ancient Precambrian Archean granite, gneiss, and greenstone belt rocks. Both terrains are effectively calcium-poor. While the Yellowstone River crosses Cretaceous Montana Group shale and sandstone in its middle course, these formations contribute limited calcium, and the river's substantial discharge dilutes any mineral content from lower calcareous units in the Billings area.

With hardness at 60 mg/L, Billings residents experience minimal to moderate scale accumulation in household use. Faucet aerators and showerheads develop light deposits over extended periods — bi-monthly cleaning with citric acid solution is sufficient. Dishwashers produce clean glassware with minimal rinse-aid. Hot water systems remain largely scale-free. City of Billings Public Works Water Division consistently delivers water meeting all Montana DEQ and EPA Safe Drinking Water Act requirements.