North Chicago Water Hardness & Quality Report (2026)

The City of North Chicago Public Works Department operates the municipal water utility, serving approximately 35,000 residents in North Chicago, Lake County, Illinois. The primary source is Lake Michigan via a 6,500-foot deep intake crib, supplemented potentially by groundwater wells. Water is treated at the city's filtration plant using conventional processes — intake screening, coagulation, sedimentation, filtration, and disinfection — to meet state and federal standards. The service area covers the city and adjacent zones in northern Lake County near the Illinois-Wisconsin border.

Lake Michigan is part of the Great Lakes basin, underlain by Paleozoic bedrock of dolomite, limestone, and shale from the Silurian and Devonian periods, overlain by Quaternary glacial till and sand deposits. Lake Michigan's vast glacial meltwater chemistry is shaped by low residence time, yielding very soft water low in dissolved minerals. However, any groundwater components derive from the shallow glacial drift aquifer or the deeper Silurian dolomite aquifer, where prolonged contact with carbonate rocks elevates calcium and magnesium content, contributing to a hard blended supply overall.

Hard water leaves scale deposits on fixtures, dishes, and glassware, causing white buildup in kettles and toilets. Most affected appliances — water heaters, dishwashers, washing machines, and coffee makers — can see efficiency drop 20–50% from mineral insulation, shortening lifespan and raising energy costs. Maintenance tips include cleaning fixtures monthly with vinegar and flushing water heaters yearly. A water softener is recommended to prevent scale and extend appliance life. The 2023 Consumer Confidence Report confirms compliance with all EPA standards, including no lead or copper violations; pH is typically 7.5–8.5 and disinfection byproducts (TTHMs, haloacetic acids) remain below MCLs.