Azusa Water Hardness & Quality Report (2026)

Azusa Light & Water serves approximately 110,000 residents in Azusa, Los Angeles County, California. The utility blends surface water drawn from the San Gabriel River near the mouth of San Gabriel Canyon with local groundwater. Surface water is treated at the Joseph F. Hsu Filtration Plant, which uses low-pressure membrane filtration with a capacity of up to 12 million gallons per day. The utility can be reached at 729 N. Azusa Ave., Azusa, CA 91702, or by phone at 626-812-5225.

The San Gabriel River watershed spans the San Gabriel Mountains, where snowmelt and rainfall interact with granitic batholiths and metamorphic terrains of the Mesozoic Peninsular Ranges Batholith, including gneiss and schist formations that contribute calcium and magnesium to the runoff. Local groundwater comes from alluvial aquifers in the Pomona Valley, formed from unconsolidated Quaternary sediments that leach additional hardness ions from upstream geological deposits. The prolonged contact of both surface and subsurface water with this mineral-rich geology produces a characteristically hard supply.

Hard water promotes scale buildup in pipes, water heaters, dishwashers, and washing machines, reducing efficiency and lifespan. White deposits on fixtures and reduced soap lathering are common. Regular vinegar descaling, drain screens, and scale inhibitors help with maintenance, and a water softener is recommended for households with hard supply to prevent appliance damage. The 2024 Consumer Confidence Report shows pH averaging 7.6, sodium at 31 mg/L, and hardness at 150 mg/L. TTHM levels average 31.5 μg/L, well below the 80 μg/L MCL, and turbidity meets treatment technique standards. No MCL violations are reported, though independent analysis notes potential PFAS concerns, making point-of-use filtration a prudent option.