Alameda County, California: drinking water report. Alameda County spans from Oakland to Fremont, Livermore to Berkeley, serving about 1.7 million residents…
Alameda County spans from Oakland to Fremont, Livermore to Berkeley, serving about 1.7 million residents through multiple water agencies. East Bay Municipal Utility District (EBMUD) is the largest provider, drawing from the Mokelumne River in the Sierra Nevada foothills via a 90-mile aqueduct. Southern county communities are served by the Alameda County Water District and Zone 7 Water Agency, which rely on a mix of imported State Water Project water and local groundwater.
EBMUD's Sierra Nevada source water is generally high quality, similar to Seattle's protected watershed model. But Alameda County's southern communities face a different situation. The Livermore-Amador Valley has documented groundwater contamination from historical industrial activities, including the former Lawrence Livermore National Laboratory, which is an active Superfund site.
UCMR5 data shows PFAS detections in several county water systems, with the highest concentrations in systems drawing groundwater in the Tri-Cities area (Fremont, Newark, Union City). According to the California State Water Resources Control Board, eight public water systems in Alameda County reported PFAS above notification levels.
Your water quality in Alameda County depends heavily on which agency serves you. EBMUD customers in Oakland and Berkeley drink Sierra Nevada water. Residents in Fremont or Livermore drink a different supply entirely.
Check your water to identify your provider and see the latest contaminant data. If PFAS is present, reverse osmosis or certified activated carbon filters are effective options. Our water filter guide helps you match filter type to your specific situation. Pull your detailed report, and see our California page for statewide data.
Drinking water is one exposure route. These federal datasets also cover Alameda County, CA.
The EPA places Alameda County, CA in Zone 2 - a moderate-risk category, with a predicted average indoor radon level between 2 and 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
67% of homes in Alameda County, CA were built before 1980, and 26% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Alameda County, CA averages 8.4 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide