Westmont Water Hardness & Quality Report (2026)

Westmont, an unincorporated community in Los Angeles County, receives its water supply from the Los Angeles Department of Water and Power (LADWP). Sources are mixed, blending local groundwater from the Central Groundwater Basin (including the Hollywood and Central Basins) with imported surface water via the Los Angeles Aqueduct, Colorado River Aqueduct, and California State Water Project (including Castaic Lake reservoir). Treatment occurs at the Jensen and Griffith filtration facilities using filtration, chloramination, and corrosion control, drawing from the Owens Valley watershed, Colorado River Delta, and Sierra Nevada snowmelt catchments.

The groundwater component taps the vast Los Angeles Foreland Basin aquifers, formed by thick alluvial fans and sedimentary layers from the Tertiary period, including the Fernando Formation with marine sandstones and shales. The San Fernando Valley Groundwater Basin is underlain by Quaternary alluvial deposits and Pleistocene sedimentary formations rich in calcium and magnesium-bearing minerals. Carbonate-rich limestones and evaporitic deposits impart a hard character to the water through mineral dissolution, while blending of multiple sources moderates the extreme mineralization typical of pure groundwater supplies in this region.

Hard water in this range leads to moderate scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan. Faucet aerators and showerheads may clog noticeably within 1–2 years without maintenance, and regular vinegar descaling or installation of a water softener is recommended—particularly for homes with older galvanized plumbing. LADWP water typically maintains a pH of 7.5–8.5, meeting all federal and state standards; the utility reports no PFAS exceedances, with trace levels treated via granular activated carbon, and monitors low levels of chromium-6 and disinfection byproducts, all below applicable MCLs.