What was found in San Diego's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 2768.5 µg/L 28% of the EPA limit 10000 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Fluoride | 760 µg/L 19% of the EPA limit 4000 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019
Highest in the city: 1960 µg/L — BUTTERFIELD RANCH · 353 people · 2014 | 3/4 | SYR4 |
| Nitrate-Nitrite | 612.5 µg/L 6.1% of the EPA limit 10000 µg/L Highest in the city: SAN DIEGO COUNTY WATER AUTHORITY · 0 people · 2019 | 1/4 | SYR4 |
| Chlorite | 452.8 µg/L 45% of the EPA limit 1000 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 1/4 | SYR4 |
| Barium | 135 µg/L 6.8% of the EPA limit 2000 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Combined Uranium | 71.52 µg/L 238% of the EPA limit, at the 95th percentile of samples — 30 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Lithium | 65 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2023 | 2/4 | UCMR-5 |
| TTHM | 64.63 µg/L 81% of the EPA limit 80 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Dibromochloromethane | 26.31 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Gross Beta Particle Activity | 24.95 pCi/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 2/4 | SYR4 |
| Bromoform | 23.87 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Trichloroacetic Acid | 4.5775 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019
Highest in the city: 23.25 µg/L — NAS NORTH ISLAND & NAB CORONADO · 36,990 people · 2019 | 3/4 | SYR4 |
| Bromodichloromethane | 18 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Total Haloacetic Acids (HAA5) | 16.8 µg/L 28% of the EPA limit 60 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Chloroform | 15.2 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019
Highest in the city: 15.6 µg/L — SAN DIEGO COUNTY WATER AUTHORITY · 0 people · 2019 | 3/4 | SYR4 |
| Dibromoacetic Acid | 11.36 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Bromate | 9.744 µg/L 97% of the EPA limit 10 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 2/4 | SYR4 |
| Dichloroacetic Acid | 8.929 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Selenium | 6.7985 µg/L 14% of the EPA limit 50 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019
Highest in the city: 8 µg/L — BUTTERFIELD RANCH · 353 people · 2014 | 2/4 | SYR4 |
| Trichloroethylene | 4.5 µg/L 90% of the EPA limit 5 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 1/4 | SYR4 |
| Tetrachloroethylene | 4.335 µg/L 87% of the EPA limit 5 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 1/4 | SYR4 |
| Arsenic | 3.3 µg/L 33% of the EPA limit 10 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 2/4 | SYR4 |
| Monobromoacetic Acid | 3.065 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 2/4 | SYR4 |
| Monochloroacetic Acid | 2.5125 µg/L No EPA limit set Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 3/4 | SYR4 |
| Mercury | 1.9 µg/L 95% of the EPA limit 2 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 1/4 | SYR4 |
| cis-1,2-Dichloroethylene | 0.9525 µg/L 1.4% of the EPA limit 70 µg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2019 | 1/4 | SYR4 |
| Dichloromethane | 0.5770 µg/L 12% of the EPA limit 5 µg/L Highest in the city: SAN DIEGO COUNTY WATER AUTHORITY · 0 people · 2019 | 1/4 | SYR4 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: SAN DIEGO, CITY OF · 1,385,379 people · 2023 | 3/4 | LCR |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving San Diego
| Supplier | Population served |
|---|---|
| SAN DIEGO, CITY OF | 1,385,379 |
| NAS NORTH ISLAND & NAB CORONADO | 36,990 |
| BUTTERFIELD RANCH | 353 |
| SAN DIEGO COUNTY WATER AUTHORITY | 0 |
Frequently asked questions about San Diego tap water
Is San Diego tap water safe to drink?
EPA testing detected 28 contaminants in the water serving San Diego. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve San Diego?
4 public water suppliers report drinking-water monitoring for San Diego, California to the EPA. Each is listed above with its population served.
What contaminants are in San Diego's water?
The contaminants EPA monitoring detected in San Diego include Nitrate, Fluoride, Nitrate-Nitrite, Chlorite, Barium. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.