Chatham Water Hardness & Quality Report (2026)

The Village of Chatham Water Department serves approximately 12,000 residents in Chatham, Sangamon County, Illinois, a suburb south of Springfield. The primary water source is treated surface water from Lake Springfield, a man-made reservoir formed by damming the Sangamon River, managed through the Chatham Water Treatment Plant. This facility processes raw lake water using coagulation, sedimentation, filtration, and chlorination to meet drinking standards before distribution across the village's service area, covering residential, commercial, and municipal needs within the West Zone of the regional supply network.

Lake Springfield lies within the Sangamon River watershed, spanning glacial till plains and dissected uplands of the Illinois till plain ecoregion. Underlying geology features Mississippian Salem and St. Louis limestones, Pennsylvanian shales, and Quaternary glacial deposits that contribute dissolved minerals to the surface water. This hard supply reflects the limestone-dominated terrain, where natural dissolution of carbonate-rich rock and magnesium-bearing shales enriches the water with alkaline earth metals, creating a mineralized profile without reliance on groundwater aquifers.

Very hard water promotes limescale buildup in pipes, heaters, and fixtures, shortening the lifespan of water heaters, dishwashers, and washing machines by up to 30%. It reduces soap efficiency, leaves spots on glassware, and stains bathroom surfaces. Regular vinegar descaling and installing sediment filters are recommended, and a whole-house softener is advised to mitigate these effects. Annual Consumer Confidence Reports confirm compliance with EPA standards, including no violations for lead or copper; no PFAS exceedances were reported in recent UCMR sampling, and pH typically ranges 7.5–8.5, supporting stable distribution.