Martinez Water Hardness & Quality Report (2026)

The City of Martinez Water System serves approximately 35,546 to 38,000 residents in Martinez, California, within Contra Costa County. Water is sourced from surface water and treated at the city's Water Plant located at 525 Henrietta Street. Treatment processes include coagulation, flocculation, sedimentation, ozonation, filtration, and chloramination. A recent major infrastructure project enhanced the ozonation facility for improved disinfection and contaminant removal, including metals. The utility can be reached at 925-372-3500.

The watershed for Martinez's surface water is influenced by the East Bay's diverse geology, featuring sedimentary rock formations from ancient marine environments millions of years old. Limestone and other carbonate-rich layers in Contra Costa County shape the water's moderately mineralised profile through natural dissolution of minerals. No specific aquifer is utilized; instead, the supply reflects the regional geology of the East Bay hills, where prehistoric seabeds left enduring mineral deposits, resulting in noticeable mineral content without extreme softness or hardness.

Martinez's moderately hard water leads to scale buildup in household systems, reducing efficiency and potentially damaging appliances including water heaters, dishwashers, washing machines, and faucets — with annual repair costs estimated at $930–1,580 without treatment. Plumbing fixtures may develop limescale, shortening lifespan and increasing energy bills. Regular vinegar descaling, drain screens, and biannual water heater flushing are recommended. A whole-home softener is advised for comprehensive protection. Water quality testing reveals 5–8 contaminants with 2–5 exceeding health guidelines, including haloacetic acids (HAA5), total trihalomethanes (TTHMs), chromium (hexavalent), and arsenic, though no MCL violations were reported as of 2025.