Marshall Water Hardness & Quality Report (2026)

Marshall Municipal Utilities (MMU) delivers water to about 14,000 residents and businesses in Marshall, Minnesota. Their sole water source is groundwater drawn from wells that tap into the Jordan Aquifer. This water is then processed at the MMU Water Treatment Plant. Unlike some communities, Marshall doesn't rely on surface water like rivers or lakes, ensuring a consistent supply managed locally. The groundwater originates from the Upper Mississippi River Basin, specifically from precipitation that seeps into the glacial drift and bedrock of the Coteau des Prairies region.

The geology beneath Marshall plays a significant role in the water's character. The Jordan Sandstone and underlying Cambrian formations are rich in limestone and dolomite. As groundwater filters through these rock layers, it picks up dissolved minerals, particularly calcium and magnesium, which are characteristic of the region's karst-influenced geology. This natural enrichment process, typical of southwestern Minnesota's prairie landscape, results in a hard water supply without the diluting effect of surface water runoff.

Homeowners in Marshall may notice scale buildup in appliances like water heaters, dishwashers, and washing machines. This mineral accumulation can reduce efficiency and shorten the lifespan of these devices, often appearing as white deposits on fixtures and diminishing the lathering ability of soaps. To combat these effects, routine maintenance such as annual deliming of heaters and the use of high-efficiency detergents are advised. Installing a water softener is a common recommendation for households seeking to prevent scaling and improve overall cleaning performance. The water's pH generally falls between 7.2 and 7.8, and while naturally occurring iron and manganese are managed through treatment, the water meets all EPA standards, with lead and copper levels well within safe limits and no detected PFAS.