Cerritos Water Hardness & Quality Report (2026)

City of Cerritos Water Division operates the municipal water utility, serving approximately 50,000 residents across 8 square miles in Los Angeles County, California. In 2024, the utility supplied 100% of its 2.32 billion gallons of drinking water from three local deep wells (C-2, C-4, and others) in the Central Groundwater Basin, with no reliance on imported surface water from the Metropolitan Water District (MWD) that year. Water undergoes basic disinfection and monitoring, with groundwater acting as a natural filter.

The Central Groundwater Basin, part of the vast Los Angeles Basin groundwater system, is recharged via managed seepage from the Rio Hondo and San Gabriel Rivers in the Montebello Forebay. This imported water originates from the Colorado River Aqueduct and the State Water Project (northern California reservoirs). Local geology involves Quaternary alluvial sediments and older sedimentary rock formations rich in minerals, which dissolve into the aquifers. This imparts a hard character through natural leaching of calcium, magnesium, and manganese from soils and rocks.

Scale buildup on pipes, faucets, and appliances is the primary concern — most affected are water heaters, dishwashers, washing machines, and coffee makers, where mineral deposits can clog elements and valves. Regular maintenance like vinegar descaling and flushing heaters helps mitigate issues. A water softener may be considered for heavy users to prevent spotting and laundry stiffness. In 2024, manganese levels reached 34–38 µg/L in select wells (below the 50 µg/L aesthetic standard but above health advisory), from natural leaching. No lead or galvanized service lines were found per LCRR inventory, and all EPA and state standards are met.