Davenport Water Hardness & Quality Report (2026)

Davenport, Iowa — the largest of the Quad Cities at the Iowa–Illinois border on the Mississippi River — draws its municipal water supply from the Mississippi River via the City of Davenport Water Division, operating an intake on the Mississippi River in Scott County, Iowa. The Mississippi at the Davenport reach has collected drainage from the vast upper Mississippi Basin — including Wisconsin, Minnesota, Iowa, and Illinois headwater drainages. Water hardness measures 176 mg/L — classified as hard.

Davenport's hard supply reflects the carbonate-rich geology of the upper Mississippi River watershed at the Quad Cities. The Mississippi at Davenport receives drainage from: Wisconsin Driftless Area streams — draining Ordovician–Silurian dolomite and Devonian limestone outcrops of the unglaciated Driftless zone; Iowa loess and glacial carbonate till drainage from the Iowa prairie watershed; Illinois carbonate terrain of the Central Lowlands; and Minnesota Prairie glacial lake sediment carbonate-laden drainage. The upper Mississippi's hard character reflects the regional dominance of Silurian dolomite, Devonian limestone, and Ordovician Prairie du Chien Group dolomite in the watershed, all of which dissolve readily into tributary drainage.

At 176 mg/L, Davenport residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, shower glass, and tile within weeks — monthly descaling with citric acid solution is standard maintenance. Dishwashers produce better results with rinse-aid, and water heaters benefit from annual inspection for element scale. Davenport Water Division consistently delivers water meeting all Iowa DNR and EPA Safe Drinking Water Act requirements.