Dubuque Water Hardness & Quality Report (2026)

Dubuque Water Works is the public utility serving the city of Dubuque, Iowa, and surrounding areas in Dubuque County. Drinking water is drawn entirely from groundwater sources — specifically the Apple-Plum Alluvial aquifer and the Jordan (Cambrian-Ordovician) aquifer within the Mississippi River watershed. Treatment occurs at utility facilities employing filtration, softening, and disinfection with hypochlorite, delivering water compliant with EPA standards to residential and commercial customers across the region. The utility can be contacted at 563-589-4291 or through www.cityofdubuque.org/water for full Consumer Confidence Report details.

The Apple-Plum Alluvial aquifer consists of unconsolidated sand and gravel deposits in river valley sediments along the Mississippi River, susceptible to surface recharge influences per Iowa DNR assessments. The deeper Jordan aquifer taps ancient Cambrian-Ordovician bedrock composed of sandstone and dolomite, part of eastern Iowa's limestone-rich karst system. These carbonate-dominated formations dissolve readily, leaching calcium and magnesium into the groundwater over geological time and imparting a consistently hard, mineral-rich character to the supply.

At the hard classification, scale buildup is significant in water heaters, dishwashers, washing machines, and plumbing fixtures, causing reduced flow, higher energy use, and frequent repairs. Maintenance measures include regular vinegar descaling, installing sediment filters, and flushing systems; a whole-house water softener is strongly recommended to mitigate mineral accumulation and extend equipment life. Treatment includes filtration, softening, and hypochlorite disinfection, with two contaminants having exceeded EPA health-based guidelines in past reports — review the latest Consumer Confidence Report at www.cityofdubuque.org for current data.