Manhattan Beach Water Hardness & Quality Report (2026)

Manhattan Beach Water Department serves over 36,000 residents in Manhattan Beach, California, in Los Angeles County along the Pacific Coast. Water sources are mixed, blending local groundwater from the West Coast Groundwater Basin with imported surface water via the Metropolitan Water District of Southern California (MWD). Key supplies include the Colorado River Aqueduct and the California State Water Project (SWP), with treatment occurring at MWD's Robert B. Diemer Filtration Plant and Jensen Treatment Plant. Local groundwater is extracted from municipal wells and receives basic treatment before distribution.

Local groundwater percolates through alluvial fans and fractured bedrock of the San Pedro Formation (Pleistocene), interacting with marine sedimentary layers in the Los Angeles Coastal Watershed. Imported Colorado River water traverses limestone-dominated formations in the Rocky Mountains and desert basins, while State Water Project sources from Sierra Nevada reservoirs contact granitic and metavolcanic rocks. This geology imparts a hard character to the supply, with elevated dissolved minerals from prolonged contact with carbonate rocks and evaporitic deposits.

At hard levels, scale buildup manifests as white deposits in pipes, fixtures, and appliances like water heaters, dishwashers, and coffee makers, reducing efficiency and lifespan. Laundry feels stiff, and soap lathering is poor, often requiring more detergent. Periodic vinegar descaling and a water softener are strongly recommended. The 2018 Consumer Confidence Report indicates compliance with federal and state standards, with pH typically 7.5–8.5; no lead or copper action level exceedances are reported, corrosion control is managed via pH adjustment and orthophosphate dosing, and PFAS monitoring shows non-detects or below notification levels.