Fort Collins Water Hardness & Quality Report (2026)

Fort Collins, Colorado draws its municipal water supply from the City of Fort Collins Utilities, sourcing from two primary origins: the Cache la Poudre River (often called the Poudre) at a direct intake on the river, and stored water from Horsetooth Reservoir — a component of the Colorado–Big Thompson Project (CBT) that imports water from the western slope of the Rockies through the Alva B. Adams Tunnel beneath Rocky Mountain National Park. Water from both sources is treated at the Soldier Canyon Filter Plant and the Water Treatment Plant in Larimer County before distribution. Water hardness in Fort Collins measures 129 mg/L — classified as moderately hard.

Fort Collins' moderate hardness reflects a blend of Rocky Mountain Front Range and western slope water sources. The Cache la Poudre originates in the Never Summer Mountains and Mummy Range of the Rockies, draining Precambrian Idaho Springs Formation gneiss, schist, and Pikes Peak Granite — calcium-poor crystalline metamorphic and igneous basement. However, as the Poudre descends through the Precambrian and Paleozoic formations of the Front Range foothills — crossing some Cretaceous Pierre Shale and Niobrara Chalk sequences before reaching Fort Collins — it accumulates moderate calcium bicarbonate. CBT water from the western slope adds some additional mineral content, producing the moderately hard final blend.

At 129 mg/L, Fort Collins residents encounter moderate scale formation in household use. Faucet aerators and showerheads develop deposits over several months — monthly descaling with citric acid solution keeps them operating well. Kettles develop a moderate mineral film that benefits from periodic treatment. Dishwashers produce consistently cleaner glassware with rinse-aid, and water heaters benefit from an annual inspection for element scaling. Fort Collins Utilities consistently delivers water meeting all Colorado CDPHE and EPA Safe Drinking Water Act requirements.