Clinton Water Hardness & Quality Report (2026)

Clinton, Iowa, the Clinton County seat — a major east Iowa Mississippi River industrial and historical city (Clinton is the Clinton County seat — one of the most historically significant cities on the upper Mississippi River; Clinton was one of the most important lumber processing centers in the United States in the latter half of the 19th century (Clinton was a major center of the north woods lumber boom — logs were floated down the Mississippi River from the forests of Wisconsin and Minnesota and processed at the enormous sawmills in Clinton; at its peak, Clinton had more millionaires per capita than any city in the United States, a fact frequently cited in its local history (the Clinton area's lumber barons built the extraordinary Victorian mansions that still stand in the city's historic districts)); Clinton was also an important early industrial city (the Clinton Corn Processing facility — one of the major corn wet milling operations in the Iowa and Mississippi River corridor — represents Clinton's transition from lumber to industrial corn processing, and the Clinton industrial corridor has been a significant employer for over a century)), a diverse Clinton County community with a significant working-class, industrial, and Mississippi River Valley heritage population — draws its municipal water supply from the Mississippi River via the City of Clinton Water Division. Water hardness in Clinton measures 286 mg/L — classified as extremely hard.

Clinton's extreme hardness reflects the east Iowa Clinton County Mississippi River Valley carbonate's extremely calcareous character. The Mississippi River at Clinton draws dissolved carbonates from the upper Mississippi River valley Silurian Niagaran Dolomite and Devonian carbonate; no softening produces the extreme 286 mg/L.

At 286 mg/L, Clinton residents face severe hard water challenges. Daily descaling, water softeners, and appliance protection are strongly recommended. City of Clinton Water Division consistently delivers water meeting all Iowa DNR and EPA Safe Drinking Water Act requirements.