Metals
Boron in U.S. tap water
57 public water systems across 5 U.S. states report Boron in their annual Consumer Confidence Report. 7 sit at or above the federal limit.
What it is
A naturally occurring element from rock and soil.
Why it's regulated
No enforceable federal limit; the EPA has issued a health advisory level.
At or above the federal limit (7)
| Water system | Measured | vs. limit |
|---|---|---|
| Oxnard, CA 2024 annual report | 462.5 ug/L | 462.5× the limit |
| Burbank, CA 2024 annual report | 140–170 ug/L | 170.0× the limit |
| Inglewood, CA 2023 annual report | 150 ug/L | 150.0× the limit |
| Pomona, CA 2024 annual report | 140 ug/L | 140.0× the limit |
| West Covina, CA 2024 annual report | 140 mg/L | 140.0× the limit |
| Hayward, CA 2024 annual report | 44 ug/L | 44.0× the limit |
| Charlotte, NC 2024 annual report | 31 ug/L | 4.4× the limit |
Within the federal limit (42)
| Water system | Measured |
|---|---|
| Wilmington, NC 2024 annual report | 50.2 |
| Chula Vista Sweetwater, CA 2024 annual report | 0.08–0.54 mg/L |
| San Diego, CA 2023 annual report | 0.4 mg/L |
| El Cajon, CA 2024 annual report | 0.39 mg/L |
| Simi Valley, CA 2024 annual report | 0.28 mg/L |
| Thousand Oaks, CA 2024 annual report | 0.27–0.28 mg/L |
| Ventura, CA 2023 annual report | 0.2 mg/L |
| Fullerton, CA 2024 annual report | 0.18 mg/L |
| Vacaville, CA 2024 annual report | 0.18 mg/L |
| Tracy, CA 2024 annual report | 1.6 mg/L |
| Bakersfield, CA 2024 annual report | 0.15 mg/L |
| Irvine, CA 2023 annual report | 0.15 mg/L |
| Santa Ana, CA 2024 annual report | 0.14 mg/L |
| Huntington Beach, CA 2025 annual report | 0.13 mg/L |
| Escondido, CA 2024 annual report | 0.11 mg/L |
| Daly City, CA 2024 annual report | 41 ug/L |
| San Francisco SFPUC, CA 2023 annual report | 41 ug/L |
| San Mateo, CA 2024 annual report | 0.04 mg/L |
| Alameda, CA 2024 annual report | Not detected ug/L |
| Albany, CA 2024 annual report | Not detected ug/L |
| Berkeley, CA 2024 annual report | Not detected ug/L |
| Castro Valley, CA 2024 annual report | Not detected ug/L |
| Crockett, CA 2024 annual report | Not detected ug/L |
| El Cerrito, CA 2024 annual report | Not detected ug/L |
| El Sobrante, CA 2024 annual report | Not detected ug/L |
| Emeryville, CA 2024 annual report | Not detected ug/L |
| Hayward, CA 2024 annual report | Not detected ug/L |
| Hercules, CA 2024 annual report | Not detected ug/L |
| Kensington, CA 2024 annual report | Not detected ug/L |
| Lafayette, CA 2024 annual report | Not detected ug/L |
| Moraga, CA 2024 annual report | Not detected ug/L |
| Oakland, CA 2024 annual report | Not detected ug/L |
| Orinda, CA 2024 annual report | Not detected ug/L |
| Piedmont, CA 2024 annual report | Not detected ug/L |
| Pinole, CA 2024 annual report | Not detected ug/L |
| Richmond, CA 2024 annual report | Not detected ug/L |
| Rodeo, CA 2024 annual report | Not detected ug/L |
| Salinas, CA 2024 annual report | Not detected mg/L |
| San Leandro, CA 2024 annual report | Not detected ug/L |
| San Lorenzo, CA 2024 annual report | Not detected ug/L |
| San Pablo, CA 2024 annual report | Not detected ug/L |
| Stockton, CA 2024 annual report | Not detected mg/L |
Frequently asked
+What is Boron?
A naturally occurring element from rock and soil. No enforceable federal limit; the EPA has issued a health advisory level.
+What is the federal limit for Boron in drinking water?
The federal NL for Boron is 1 ug/L. The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Boron over the federal limit?
7 of the 57 public water systems on The Water Map report Boron at or above its federal limit, spanning 5 U.S. states. The full list is on this page.
+How can I check if Boron is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Boron.