Florence-Graham Water Hardness & Quality Report (2026)

The Florence-Graham Water System, operated by Golden State Water Company (GSWC), serves the Florence-Graham area in Los Angeles County, California. The utility delivers a blend of three water sources: groundwater pumped from the Central Groundwater Basin, water imported via the Colorado River Aqueduct, and water from the State Water Project — both imported and distributed by the Metropolitan Water District of Southern California. This multi-source approach ensures reliable supply across the service territory.

The Central Groundwater Basin is a Quaternary alluvial aquifer composed of unconsolidated sand, silt, and clay deposits overlying Tertiary marine sediments, bounded on the north by the Elysian, Repetto, Merced, and Puente hills and on the west by the Newport-Inglewood Fault Zone. Imported surface water originates from the Colorado River, draining Cretaceous and Paleozoic rock formations across the Colorado Plateau, and from the State Water Project's northern California sources. The geology of both groundwater and surface water sources contributes elevated dissolved calcium and magnesium, yielding a very hard water supply.

Florence-Graham's water is classified as very hard, meaning scale buildup in pipes, water heaters, and appliances is a significant concern. Dishwashers, washing machines, and hot water heaters are particularly vulnerable to mineral deposits that reduce efficiency and shorten equipment lifespan. Soap and detergent effectiveness is reduced, requiring higher doses for cleaning. A water softener is strongly recommended for households seeking to mitigate these effects and extend appliance longevity. The system maintains compliance with all federal and state drinking water standards, with monitoring for lead and copper under the Lead and Copper Rule and corrosion control measures in place.