Suisun Water Hardness & Quality Report (2026)

Suisun-Solano Water Authority (SSWA) provides drinking water to Suisun City and surrounding areas in Solano County, California, through a partnership with the Solano Irrigation District. The primary source is surface water from Lake Berryessa, delivered via the Solano Project and treated at SSWA facilities before distribution to approximately 60,000 residents. Lake Berryessa is impounded by Monticello Dam on Putah Creek, part of the Sacramento River watershed within the California Coast Ranges, serving as the principal reservoir for the regional supply.

The watershed encompasses the upper Putah Creek drainage basin within the California Coast Ranges, feeding into Lake Berryessa reservoir. The surrounding geology features Mesozoic-age Franciscan Complex bedrock — a subduction zone mélange of greywacke sandstones, shales, and serpentinite — with overlying Quaternary volcanic and sedimentary deposits from the Clear Lake Volcanics. Limestone and dolomite outcrops within these formations dissolve calcium and magnesium ions into the reservoir, imparting a hard water character consistent with mineral-rich surface supplies in the Vaca Mountains.

Hard water from Lake Berryessa leads to scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and shortening appliance lifespan. White deposits form on fixtures and more detergent or energy is required for effective cleaning. Regular vinegar descaling, installing scale inhibitors, or a water softener is recommended to mitigate staining and soap scum. The 2023 Consumer Confidence Report confirms this supply meets Safe Drinking Water Act standards, with treatment including coagulation, filtration, disinfection, and corrosion control; no exceedances of lead or copper action levels were reported, low PFAS detections remain below notification levels, and pH typically measures 7.5–8.5 with disinfection byproducts closely monitored.