Fairfield Water Hardness & Quality Report (2026)

The City of Fairfield Public Works Water Division serves approximately 120,000 residents in Solano County, California, primarily in the city of Fairfield (ZIP 94533–94535). The utility sources its drinking water from Lake Berryessa reservoir and the Sacramento Delta, conveyed via the Putah South Canal and North Bay Aqueduct. Treatment occurs at two conventional plants: the Waterman Treatment Plant and the jointly owned North Bay Regional Water Treatment Plant (NBR) with Vacaville. The system has consistently met USEPA and State drinking water health standards, as confirmed in annual reports available on the city's website.

The watershed encompasses the upper Sacramento River basin feeding Lake Berryessa, and extends to the Sacramento-San Joaquin Delta. Water percolates through alluvial sediments and sedimentary rock formations in the Sacramento Valley, including gypsum and limestone deposits from ancient geological periods. This geology contributes to a hard supply, with substantial dissolved calcium and magnesium influencing the water's chemistry and requiring specific treatment considerations at the plants to ensure potability.

At hard water levels, scale buildup is a primary concern — white crusty deposits form on faucets, showerheads, and pipes alongside soap scum in bathrooms. Water heaters suffer efficiency losses up to 29%, requiring replacement every 6–8 years; washing machines demand 35% more detergent; and energy bills rise as appliances work harder. Maintenance includes regular cleaning of aerators and fixtures, installing scale inhibitors, and flushing water heaters biannually. A water softener is recommended to mitigate these effects. The city's 2022 Water Quality Report affirms compliance with all primary standards, with no lead or copper violations; fluoride is added for dental health, and treatment involves conventional coagulation, sedimentation, filtration, and chlorine disinfection.