Sioux Falls Water Hardness & Quality Report (2026)

The City of Sioux Falls Water Division, part of the Public Works Department, supplies water to residents in Minnehaha County and parts of Lincoln County, serving a population of over 200,000 in South Dakota. Water is primarily sourced from the Big Sioux River, with key treatment facilities including the North Treatment Plant and the Water Reclamation Facility for wastewater management. The utility maintains a distribution system spanning hundreds of miles of pipes across the service area.

The Big Sioux River watershed drains approximately 9,000 square miles across South Dakota, Minnesota, Iowa, and Nebraska, originating in the Coteau des Prairies region. The geology features glacial till, loess deposits, and Cretaceous shale bedrock from the Pierre Formation, overlain by Quaternary glacial aquifers in some areas. Limestone and dolomite outcrops contribute dissolved minerals, resulting in a hard supply through natural leaching of calcium and magnesium from sedimentary rock formations during the water cycle.

Hard water causes scale buildup from mineral deposits in water heaters, dishwashers, washing machines, and faucets, reducing efficiency and lifespan. Boilers and coffee makers may require frequent descaling. Regular cleaning of aerators and showerheads, vinegar soaks for appliances, and installing a water softener at the point of entry is recommended to prevent spotting on dishes, dry skin, and appliance wear. Sioux Falls water typically has a pH of 7.5–8.5, meeting EPA standards, with lead and copper rule compliance confirmed in annual reports; no significant PFAS detections above advisory levels have been noted in recent testing, with treatment including coagulation, sedimentation, filtration, and chlorination.