San Diego CA metro: water quality. San Diego imports roughly 85% of its drinking water – a vulnerability the city has been working to reduce for decades.
San Diego imports roughly 85% of its drinking water – a vulnerability the city has been working to reduce for decades. The San Diego County Water Authority purchases Colorado River and State Water Project supplies from the Metropolitan Water District of Southern California, then distributes to the City of San Diego's Public Utilities Department and other member agencies. Chula Vista and Oceanside operate within this same imported-water framework but manage their own distribution systems. Groundwater supplements the supply in some areas, and the city's Pure Water San Diego program is scaling up potable reuse to eventually provide half the city's supply.
Across 3.3 million residents, the metro hosts one of the densest concentrations of military installations in the country – and that matters for water quality.
San Diego County is home to Marine Corps Air Station Miramar, Naval Base San Diego, Naval Air Station North Island, Marine Corps Base Camp Pendleton, and multiple smaller installations. AFFF firefighting foam has been used at all of these facilities, and PFAS contamination has been documented in groundwater near several of them.
The California Regional Water Quality Control Board has been investigating PFAS around military sites in San Diego County since 2019. Navy investigations at NAS North Island found PFOS concentrations exceeding 40,000 ppt in some groundwater monitoring wells – though these wells are not direct drinking water sources. The concern is plume migration toward municipal supply wells.
California's notification and response levels (5.1 ppt PFOA, 6.5 ppt PFOS for notification; 10 and 40 ppt for response) are among the strictest in the nation. According to the State Water Board's PFAS monitoring dashboard, eight community water systems in San Diego County have reported detections above notification levels.
The sheer density of military facilities makes San Diego's PFAS risk profile different from most American metros. Few places have as many active and former military sites within a single metropolitan area. Within California, San Diego faces higher military-related PFAS risk than the Bay Area or Los Angeles, though all three share similar concerns about imported Colorado River water quality.
The city's investment in Pure Water San Diego – a \$5 billion program to produce recycled drinking water – could change the long-term picture. Reverse osmosis, a core technology in the purification process, is effective at removing PFAS. As the program scales up, San Diego may end up with some of the most thoroughly treated drinking water in the state.
Visit our California state page for broader data.
Military families and residents near base perimeters should treat PFAS monitoring as a priority. Check your water to see what your local system has detected. If you're near Miramar, North Island, or Camp Pendleton, reviewing your data regularly matters – contamination from military sites can change as remediation progresses or as seasonal groundwater flows shift.
Our water filter guide covers filters tested against the specific PFAS compounds the Navy uses in its AFFF formulations. For a long-term view of your area's water quality, pull a detailed report.