Chico Water Hardness & Quality Report (2026)

California Water Service Company (Cal Water) provides water to the Chico system in Butte County, California, serving approximately 50,000 customers across the city of Chico and surrounding areas. The utility operates 63 groundwater wells pumping an average of 15.9 million gallons per day from the Sacramento Valley Groundwater Basin. No surface water sources or reservoirs are used; water is delivered after basic wellhead chlorination with no major treatment plants required beyond disinfection for bacterial control.

The Sacramento Valley Groundwater Basin is a vast alluvial plain formed by sediment deposition from the Sacramento River and its tributaries draining the Sierra Nevada and Cascade Range. Underlying formations consist of Quaternary alluvial sands, gravels, silts, and clays overlying older Tertiary sedimentary units. Recharge water percolates through Paleozoic-Mesozoic limestone and dolomite in the headwater zones, dissolving calcium and magnesium carbonates and elevating mineral content, resulting in a moderately mineralized groundwater supply typical of California's Central Valley basins.

Moderately hard water leads to moderate scale buildup in water heaters, dishwashers, and coffee makers, reducing efficiency and increasing energy costs over time. Soap lathering is somewhat reduced, often requiring more detergent. Annual descaling of fixtures and heaters and installing drain screens are advised. A water softener is often recommended for aesthetic improvement; those on low-sodium diets should consult a doctor due to potential sodium addition. The Chico system complies with all primary drinking water standards; no PFAS detections above notification levels have been reported in recent CCRs, and treatment is limited to chlorination given the excellent groundwater quality.