San Clemente Water Hardness & Quality Report (2026)

The Santa Margarita Water District (SMWD) serves San Clemente in Orange County, California, delivering water to approximately 70,000 residents across a 15-square-mile service area. Primary supply is imported surface water from the Metropolitan Water District of Southern California (MWD), comprising about 80–90% of the blend: 50% from the Colorado River Aqueduct (Lake Havasu/Geneva reservoirs) and 50% from the California State Water Project (Oroville Dam, Sacramento-San Joaquin Delta). Local groundwater from the San Onofre aquifer and recycled water supplement during shortages, with treatment at MWD's Skinner and Weymouth plants followed by final chloramination and fluoridation at SMWD facilities.

Water originates from the expansive Colorado River Basin watershed (245,000 sq mi) and the State Water Project's Northern California catchments, traversing arid deserts and Sierra Nevada granites. Geology features Paleozoic limestones, Mesozoic volcanics, and Cenozoic sedimentary basins like the Los Angeles Basin, where alluvial fans overlay fractured bedrock. Dissolution of carbonate rocks — dolomite and calcite — in source areas and conveyance through mineral-rich pipelines concentrates alkaline earth metals, yielding moderately mineralised to very hard water prone to scaling.

Very hard water promotes significant calcium carbonate scale buildup in pipes, heaters, and fixtures, reducing hot water heater efficiency by up to 20–30% and clogging dishwasher arms; energy bills rise 15–25% from scale-insulated tanks. A whole-house water softener is strongly recommended, along with annual vinegar descaling and magnetic descalers for prevention. SMWD's Consumer Confidence Report confirms full EPA compliance: pH 7.8–8.5, lead and copper rules met (90th percentile copper below 1.3 mg/L), no PFAS exceedances (all below 4 ppt), low THMs at 28 ppb, and occasional bromide from the Colorado River; chloramination at 2.5 mg/L free chlorine with fluoride at 0.7 mg/L.