San Diego
San Diego is building Pure Water, a multibillion-dollar program set to supply nearly half the city's water through purification, alongside the largest desalination plant in the country.
san diego, city of
surface water (rivers/reservoirs) · local government · PWSID CA3710020
Below EPA's 15 ppb lead action level at last testing.
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1
San Diego has historically imported the vast majority of its water, leaving it acutely exposed to Colorado River and statewide shortages. Its answer is Pure Water San Diego, a phased program to recycle wastewater into a drinking supply projected to provide close to half the city's water by the mid-2030s.
The region also hosts the Claude 'Bud' Lewis Carlsbad Desalination Plant — the largest seawater desalination facility in the Western Hemisphere — giving San Diego a rare combination of reuse and desalination at scale.
The dual strategy reflects a coastal city's logic: pair the lower-cost, drought-proof gallons of reuse with desalination's unlimited but energy-intensive ocean supply.
San Diego County water quality
Source: EPA SDWIS · 2026 Q1
At a glance
- Pure Water program to supply ~half the city's water
- Home to the Carlsbad desalination plant (largest in the hemisphere)
- Reducing heavy reliance on imported water
Statewide drought history
% of California in severe+ drought (Moderate (D1) now).
Source: U.S. Drought Monitor
Common questions
Is tap water safe in San Diego?
San Diego's largest water system, SAN DIEGO, CITY OF, serves about 1,385,379 people. EPA records show 0 health-based violation(s) since 2016 and a most-recent 90th-percentile lead level of 0 ppb (EPA action level is 15 ppb). Always check your own provider's annual Consumer Confidence Report.
Where does San Diego get its water?
SAN DIEGO, CITY OF draws primarily from surface water (rivers/reservoirs), part of California's supply from Sierra snowpack, Colorado River, State Water Project.
Related water issues
Potable Reuse
Advanced purification turns treated wastewater into water that meets or exceeds drinking-water standards — increasingly essential in water-stressed regions.
ExploreDesalination
Desalination offers a drought-proof supply but at high energy cost and with brine-disposal challenges — a complement to, not a replacement for, reuse.
ExploreDrought
Much of the American West is in a multi-decade dry period that researchers describe as the most severe in over a millennium, reshaping how communities plan for water.
ExploreColorado River
The river that supplies 40 million people has lost roughly a fifth of its flow since 2000, forcing a renegotiation of how seven states share the water.
Explore