Benicia Water Hardness & Quality Report (2026)

The City of Benicia Water Utility serves approximately 28,500 residents in Solano County, California. The utility operates three surface water sources: State Water Project water delivered via the North Bay Aqueduct, Lake Berryessa water transported through the Putah South Canal, and local supply from Sulphur Springs Creek diverted at Lake Herman. Water is treated at the utility's treatment facilities before distribution to the city and surrounding service area, providing residents with a reliable, regulated supply.

Benicia's water supply originates in the Sacramento-San Joaquin Delta watershed, a region characterized by Quaternary alluvial and deltaic deposits rich in dissolved minerals. As surface water percolates through these mineral-laden geological formations — primarily Tertiary marine sediments underlying the delta — it dissolves substantial quantities of calcium and magnesium. This geological setting produces the hard water character of Benicia's municipal supply, with hardness ranging from 72 to 186 mg/L as reported in the official 2021 Annual Water Quality Report. All three source waters traverse similar mineralized zones, contributing to consistent hardness system-wide.

At this hardness level, residents can expect scale buildup on appliances, reduced efficiency of soaps and detergents, and plumbing maintenance challenges over time. Water softening is recommended for households concerned about appliance longevity, particularly for water heaters and dishwashers. The 2021 Annual Water Quality Report detected eight contaminants, with two — including total trihalomethanes (TTHMs), chromium-6, and chloroform — exceeding EPA health-based guidelines (MCLGs) while meeting federal legal limits (MCLs). The utility maintains an average total organic carbon (TOC) of 1.6 mg/L with greater than 50% removal; vulnerable populations including children, pregnant women, and immunocompromised individuals may benefit from additional certified filtration.