Poway Water Hardness & Quality Report (2026)

City of Poway Water Utility serves approximately 50,000 residents in Poway, San Diego County, California. It sources 99.5% of raw water from the San Diego County Water Authority (SDCWA), drawing from the Colorado River Aqueduct and Northern California's State Water Project, with the remainder from local rainfall captured in Lake Poway (holding about 1 billion gallons). The Lester J. Berglund Water Treatment Plant processes the water through flocculation, sedimentation, disinfection, and filtration, producing around 3 billion gallons of potable water annually.

The watershed encompasses the Colorado River Basin, with aqueducts channeling water through arid desert landscapes featuring Mesozoic limestone and Cenozoic gypsum formations, and the Sacramento-San Joaquin Delta's Quaternary alluvial deposits influenced by agricultural runoff. Lake Poway collects local precipitation from the Peninsular Ranges' Precambrian to Mesozoic granitic and metamorphic rocks. Groundwater wells access confined aquifers in sedimentary rock layers saturated with calcium and magnesium over millennia. This geology imparts a hard character to the supply due to prolonged mineral dissolution.

Very hard water in Poway promotes significant scale buildup in dishwashers — causing white spots on glassware and silverware from calcium deposits — and clogs showerheads and faucets. Hot water heaters and washing machines suffer reduced efficiency from mineral accumulation, shortening appliance life. A water softener is highly recommended for households to prevent spotting and extend appliance longevity. Regular maintenance with vinegar descaling and scale-inhibiting filters helps mitigate effects. Poway's water meets or exceeds EPA and state standards; total dissolved solids measure 632 ppm, affecting taste; MTBE not detected.