San Fernando Water Hardness & Quality Report (2026)

San Fernando, California, in Los Angeles County at the northern end of the San Fernando Valley, receives its municipal water from the San Fernando Municipal Water Department, drawing primarily from local groundwater wells tapping the San Fernando Valley Groundwater Basin — one of the largest urban groundwater basins in California — supplemented by imported water from the Los Angeles Department of Water and Power (LADWP). The city of San Fernando operates its own small utility distinct from LADWP, which supplies surrounding Los Angeles neighborhoods. The San Fernando Valley basin is a broad alluvial aquifer historically recharged by the Los Angeles River and natural runoff from the surrounding mountain ranges.

The hard 179.5 mg/L hardness reflects the San Fernando Valley's complex geology and water supply blending. The valley basin is underlain by thick Pleistocene alluvial deposits derived from the surrounding Santa Monica Mountains (Cretaceous marine sedimentary rocks), San Gabriel Mountains (Precambrian and Mesozoic granites), and Verdugo Mountains — calcareous marine sediment contributions from the Santa Monica Mountains introduce calcium carbonate to the aquifer. Imported LADWP water — a blend of Owens Valley, Mono Basin, and Metropolitan Water District supply — is moderately hard and elevates overall hardness when blended with local wells.

At 179.5 mg/L, San Fernando residents experience consistently hard water throughout the home. Scale forms steadily in kettles and coffee machines, water heaters accumulate calcium insulation on elements, and shower surfaces develop persistent white deposits. Faucet aerators and showerheads require regular soaking to maintain flow. The historically contaminated San Fernando Valley Groundwater Basin — subject to decades of TCE and PCE remediation — means residents should be aware of the complex contaminant history even as treatment has improved. The PFAS level of 7.1 ppt warrants a certified reverse osmosis filter for daily drinking water in this community.