San Bernardino County, California: drinking water report. San Bernardino County is the largest county by area in the contiguous United States, but its 2.2…
San Bernardino County is the largest county by area in the contiguous United States, but its 2.2 million residents are concentrated in the western Inland Empire communities. Water comes from local groundwater basins, imported State Water Project water, and some recycled water. The county hosts dozens of independent water agencies, from large utilities like the San Bernardino Municipal Water Department to small mutual water companies serving a few hundred connections.
Groundwater contamination is a long-running issue in the western part of the county. Industrial solvents, perchlorate, and PFAS have been detected in the Bunker Hill groundwater basin, which underlies much of the San Bernardino metro area. The EPA's UCMR5 data shows PFAS detections at 18 public water systems in the county. Norton Air Force Base (now San Bernardino International Airport) is a legacy PFAS source, and the former George Air Force Base near Victorville left contamination that is still being remediated.
According to the California State Water Resources Control Board's 2024 monitoring data, several community water systems in the county exceeded the state's PFAS notification levels. The Inland Empire has some of the highest documented groundwater PFAS concentrations in Southern California outside of Orange County.
Western county residents near former military installations face the highest PFAS risk. High desert communities around Victorville and Barstow deal with different challenges – naturally occurring arsenic and uranium in some groundwater sources.
Check your water to see contaminant data mapped to your specific provider and location. Reverse osmosis filters handle the broadest range of contaminants found in this county. Our water filter guide ranks systems by verified removal performance. Pull your detailed report for trend data. Visit our California page for statewide patterns.
Drinking water is one exposure route. These federal datasets also cover San Bernardino County, CA.
The EPA places San Bernardino 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.
45% of homes in San Bernardino County, CA were built before 1980, and 7% 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 San Bernardino County, CA averages 10.2 µg/m³, above 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