Alameda Water Hardness & Quality Report (2026)

The East Bay Municipal Utility District (EBMUD) supplies water to Alameda and surrounding East Bay communities in Alameda and Contra Costa Counties, serving over 1.2 million people across 22 cities including Oakland, Berkeley, and Alameda. The primary source is surface water from the Mokelumne River watershed, impounded in Pardee Reservoir behind Pardee Dam and transported via aqueducts to treatment plants including the Sobir Bay and Oakley plants. Local blending occurs with groundwater from the Niles Cone Groundwater Basin — via Peralta/Tyson and Mowry Wellfields — managed by the Alameda County Water District (ACWD). Distribution covers 3,944 miles of pipes and 164 neighborhood reservoirs, with treatment adding chloramine for disinfection and fluoride.

The Mokelumne River watershed spans the Sierra Nevada foothills, draining granitic and metavolcanic terrains of Mesozoic age that produce very soft water naturally low in minerals. Pardee Reservoir stores this supply, capable of sustaining the region for four to six months. Blending with Niles Cone Groundwater Basin water — replenished by Alameda Creek runoff and aqueduct imports — introduces moderately mineralised character from Quaternary alluvial deposits. This geology shapes a soft overall supply, though local groundwater adds some dissolved solids, influencing the final chemistry delivered to taps.

As a soft water supply, Alameda's water causes minimal scale buildup in pipes and appliances, reducing risks to water heaters, dishwashers, and washing machines compared to harder regions. Soap lathers easily without excess minerals, leaving little residue on skin, hair, or dishes. Routine descaling is rarely needed, and water pressure remains stable over time. Water softeners are not recommended and could over-demineralise the supply. Recent EBMUD data shows pH at 9.01; full compliance on lead and copper is maintained under EPA rules. No notable PFAS detections have been reported; treatment involves chloramine disinfection, fluoridation, and blending supported by watershed protection.