Stillwater Water Hardness & Quality Report (2026)

The City of Stillwater Public Works Department supplies drinking water to Stillwater in Washington County, Minnesota, serving approximately 19,000 residents. Water originates from eight groundwater wells at depths of 83 to 305 feet within the city limits. There are no surface water treatment plants; groundwater is pumped directly to distribution after treatment at wellhead facilities. The utility complies with Minnesota Department of Health oversight and publishes annual Consumer Confidence Reports. Though Stillwater lies within the St. Croix River watershed, it draws exclusively from local groundwater aquifers rather than the river itself.

The subsurface geology features Quaternary glacial sediments overlying Cambrian-Ordovician bedrock, including the Jordan Sandstone and Oneota Dolomite formations of the Prairie du Chien Group. These carbonate and siliceous rocks slowly dissolve, releasing calcium and magnesium ions into the groundwater through natural leaching over the aquifer recharge area. The combination of glacial drift deposits and underlying limestone and dolomite bedrock drives the characteristically hard nature of Stillwater's supply.

Very hard water causes significant scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and shortening appliance lifespan. White deposits on fixtures and reduced soap lathering are common household effects. Regular maintenance includes deliming appliances annually and flushing water heaters. Installing a water softener is highly recommended to prevent scaling and extend equipment life. The 2021 CCR confirms compliance with all primary standards; elevated PFAS levels and disinfection byproducts including TTHMs, HAA9, bromodichloromethane, and chloroform have been noted — residents are advised to review the latest CCR and consider home testing for PFAS.