Glendale Water Hardness & Quality Report (2026)

Glendale Water & Power (GWP) serves approximately 200,000 residents in the City of Glendale, Los Angeles County, California. Supply is a blend of approximately 30% local groundwater from municipal wells in the San Fernando Valley aquifers and 70% imported surface water from the Metropolitan Water District of Southern California (MWD). Imported water comes primarily via the Colorado River Aqueduct and the California State Water Project, treated at facilities including the Jensen and Weymouth treatment plants. Local groundwater is extracted from municipal wells, treated for basic filtration and disinfection, and blended with MWD supplies.

The imported supply originates from the Colorado River Basin, encompassing arid regions with limestone karst and evaporite deposits. Local groundwater basins in the San Fernando Valley are formed by alluvial fans from surrounding mountains, with sedimentary formations rich in carbonate minerals. Dissolved calcium and magnesium accumulate through natural mineral dissolution in both the imported and local sources; blending moderates but does not eliminate the inherent hardness.

Very hard water leads to significant scale buildup in pipes, water heaters, dishwashers, and washing machines, with hot water systems most affected due to mineral precipitation at higher temperatures. Regular vinegar descaling for fixtures, drain screens, and appliance hardness adjustments are advised. A water softener is recommended for households to prevent scaling and extend equipment life. Water quality reports indicate compliance with federal standards; past concerns include arsenic and uranium from groundwater above some health guidelines but within legal limits. Lead and copper rule compliance is achieved through orthophosphate addition; treatment includes coagulation, flocculation, sedimentation, filtration, and disinfection.