Pierre Water Hardness & Quality Report (2026)

The City of Pierre Public Works Department supplies water to around 14,000 residents in Pierre, South Dakota, and some nearby rural areas. The primary water source comes from seven municipal wells drawing from the Pierre Formation shale and the Fox Hills aquifer, both Cretaceous sedimentary rocks. This groundwater supply is occasionally supplemented by surface water from the Missouri River, specifically from the Oahe Reservoir. All water is treated at the Pierre Water Treatment Plant, which employs processes like filtration, disinfection, and lime softening to reduce hardness.

The region's geology is dominated by the Pierre Formation, a Late Cretaceous shale and chalk unit. This formation, along with underlying sedimentary rocks like the Fox Hills Sandstone aquifer, contributes significantly to the water's mineral content. Dissolution of carbonates from limestone and dolomite influences, along with evaporitic deposits and long aquifer residence times, results in a hard water supply with elevated sulfates and dissolved solids. Blending with Missouri River water helps to moderate these mineral levels somewhat.

Homeowners in Pierre will likely notice the effects of this hard water, which can lead to significant scale buildup inside pipes, water heaters, dishwashers, and washing machines. This buildup reduces appliance efficiency and shortens their lifespan. You might also find stubborn deposits on faucets and fixtures, requiring more frequent cleaning. To combat these issues, regular descaling with vinegar, installing scale-inhibiting filters, and periodic flushing of hot water tanks are recommended. A whole-house water softener is strongly advised to minimize spotting on glassware, reduce soap scum, and protect your appliances from wear. The water's pH typically ranges between 7.5-8.5, and the City of Pierre Public Works Department actively manages the supply for compliance with EPA standards.