Davis Water Hardness & Quality Report (2026)

Davis, California, in Yolo County west of Sacramento on the Sacramento Valley floor — home of the University of California, Davis, the largest UC campus — draws its municipal water supply from the Sacramento River via the City of Davis Water Division (which switched from groundwater to Sacramento River surface water in 2016 through a new water treatment plant at the Sacramento River), supplemented by some continued local Yolo County groundwater basin wells. The transition to Sacramento River surface water dramatically changed Davis's water supply. Water hardness in Davis measures 98 mg/L — classified as moderately soft.

Davis's moderately soft supply reflects the Sacramento River's characteristics in Yolo County. The Sacramento River at Davis (Sacramento Valley corridor from the Shasta Dam–Red Bluff reach) drains the northern Sacramento Valley — a blend of: the Klamath Mountains and Trinity Alps (Jurassic–Cretaceous Klamath terrane siliceous terrain); the Sierra Nevada granodiorite tributaries (Feather, American, and lower Sacramento tributaries); and the Coast Range (Franciscan Complex — Jurassic–Cretaceous greywacke, blueschist, and chert, with some calcareous serpentinite). The Sacramento River's moderate 98 mg/L at Davis reflects the blend of mostly soft Sierra Nevada and Coast Range drainage with some calcareous contribution from the Franciscan Complex serpentinite tributaries.

With hardness at 98 mg/L, Davis residents enjoy moderately soft water with minimal scale challenges. City of Davis Water Division consistently delivers water meeting all California SWRCB and EPA Safe Drinking Water Act requirements.