Macomb Water Hardness & Quality Report (2026)

The City of Macomb Water Department provides drinking water to approximately 15,000 residents in McDonough County, Illinois. The primary source is surface water from Spring Lake, a local reservoir treated at the city's municipal treatment plant using conventional processes — coagulation, sedimentation, filtration, disinfection, and fluoridation — before distribution through the local pipeline network. No additional reservoirs or aquifers are reported in use. The city publishes an annual Consumer Confidence Report; the 2023 CCR confirms compliance with all primary standards, including zero lead detections and copper below action levels.

Spring Lake lies within the Mississippi River watershed, specifically the La Moine River sub-basin in western Illinois. The surrounding geology consists of Pleistocene glacial deposits over Ordovician and Silurian carbonate bedrock, including limestone and dolomite formations such as the Maquoketa Group and the Galena-Platteville Group. These rocks dissolve naturally during precipitation and surface runoff, releasing minerals into the reservoir. Mineral-rich glacial soils and underlying aquifer recharge further elevate calcium and magnesium content, imparting a hard character to the supply.

At moderately hard levels, scale buildup forms on fixtures and reduces efficiency in water heaters, dishwashers, washing machines, and coffee makers. Soap lathering is less effective and deposits accumulate on faucets over time. Regular vinegar descaling, installing drain screens, and flushing heaters annually help mitigate these effects; a water softener is recommended for households. The 2023 CCR records fluoride at 0.578 mg/L (MCL 4.0), nitrate at 1.2 mg/L (MCL 10), sodium at 21 mg/L, and TTHMs averaged 0.089 mg/L — all within safe limits, with no PFAS data reported and no boil advisories issued.