Metals
Mercury in U.S. tap water
66 public water systems across 12 U.S. states report Mercury in their annual Consumer Confidence Report. 2 sit at or above the federal limit.
What it is
A toxic metal from erosion of natural deposits and industrial runoff.
Why it's regulated
Long-term exposure above the federal limit can damage the kidneys.
At or above the federal limit (2)
| Water system | Measured | vs. limit |
|---|---|---|
| Winton Water & Sanitary Dist — Winton, Ca, CA 2023 annual report | 5 ug/L | 2.5× the limit |
| St Petersburg, FL 2024 annual report | 4 ug/L | 2.0× the limit |
Within the federal limit (64)
| Water system | Measured |
|---|---|
| Camp Williams-resort Water — Manhattan Beach, Ca, CA 2021 annual report | 1.2 ug/L |
| Bend, OR 2025 annual report | 1 ug/L |
| Camp Williams-resort Water — Manhattan Beach, Ca, CA 2020 annual report | 1 ug/L |
| Chandler, AZ 2024 annual report | 0.59 ug/L |
| Fort Lauderdale, FL 2024 annual report | 0.31 ug/L |
| Loma Linda, City of — Loma Linda, Ca, CA 2023 annual report | 0–0.26 ug/L |
| Grand Prairie, TX 2024 annual report | 0.252 ug/L |
| St George, UT 2024 annual report | 0–0.2 ug/L |
| Tallahassee, FL 2024 annual report | 0.1 ug/L |
| Dallas, TX 2024 annual report | 0.08 ug/L |
| Templeton Csd — Templeton, Ca, CA 2023 annual report | 0–0.08 ug/L |
| Montecito Water Dist — Santa Barbara, Ca, CA 2023 annual report | 0.05 ug/L |
| Ann Arbor, MI 2024 annual report | Not detected ug/L |
| Antelope Valley East Kern Water Agency — Palmdale, Ca, CA 2023 annual report | Not detected ug/L |
| Antelope Valley East Kern Water Agency — Palmdale, Ca, CA 2020 annual report | Not detected ug/L |
| Antelope Valley East Kern Water Agency — Palmdale, Ca, CA 2021 annual report | Not detected ug/L |
| Antelope Valley East Kern Water Agency — Palmdale, Ca, CA 2022 annual report | Not detected ug/L |
| Birmingham, AL 2024 annual report | Not detected mg/L |
| Boron Csd — Boron, Ca, CA 2022 annual report | Not detected ug/L |
| City of Hampton, VA 2024 annual report | Not detected ug/L |
| City of Newport News, VA 2025 annual report | Not detected ug/L |
| City of Poquoson, VA 2024 annual report | Not detected ug/L |
| City of Poquoson, VA 2025 annual report | Not detected ug/L |
| Cleveland, OH 2024 annual report | Not detected mg/L |
| Columbus, OH 2025 annual report | Not detected mg/L |
| Covina Irrigating Co. — West Covina, Ca, CA 2023 annual report | Not detected ug/L |
| Covina Irrigating Co. — West Covina, Ca, CA 2020 annual report | Not detected ug/L |
| Covina Irrigating Co. — West Covina, Ca, CA 2021 annual report | Not detected ug/L |
| Foothill Municipal Water Dist. — La Canada Flintridge, Ca, CA 2023 annual report | Not detected ug/L |
| Garland, TX 2024 annual report | 0–0 ug/L |
| Grand Rapids, MI 2025 annual report | Not detected ug/L |
| Hampton, VA 2025 annual report | Not detected ug/L |
| High Point, NC 2024 annual report | Not detected ug/L |
| James City County, VA 2025 annual report | Not detected ug/L |
| Lukins Brothers Water Company — South Lake Tahoe, Ca, CA 2022 annual report | Not detected ug/L |
| Mesquite, TX 2024 annual report | 0–0 ug/L |
| Mobile, AL 2024 annual report | Not detected ug/L |
| Mojave Pud — Mojave, Ca, CA 2023 annual report | Not detected ug/L |
| Montgomery, AL 2024 annual report | Not detected mg/L |
| Nacimiento Water Company — Bradley, Ca, CA 2023 annual report | Not detected ug/L |
| Nashville, TN 2023 annual report | Not detected mg/L |
| Naval Base Ventura County, Point Mugu — Point Mugu, Ca, CA 2023 annual report | Not detected ug/L |
| Naval Base Ventura County, Port Hueneme — Point Mugu, Ca, CA 2023 annual report | Not detected ug/L |
| Newport News, VA 2024 annual report | Not detected ug/L |
| North Gualala Water Company — Gualala, Ca, CA 2023 annual report | Not detected ug/L |
| North Tahoe Pud - Main — Tahoe Vista, Ca, CA 2021 annual report | Not detected mg/L |
| Plano, TX 2024 annual report | 0–0 ug/L |
| Salt Lake City, UT 2024 annual report | Not detected mg/L |
| South Tahoe Pud - Main — South Lake Tahoe, Ca, CA 2023 annual report | Not detected ug/L |
| Thermalito Water & Sewer Dist — Oroville, Ca, CA 2023 annual report | Not detected ug/L |
Showing 50 of 64. The full list is in the JSON API.
Frequently asked
+What is Mercury?
A toxic metal from erosion of natural deposits and industrial runoff. Long-term exposure above the federal limit can damage the kidneys.
+What is the federal limit for Mercury in drinking water?
The federal MCL for Mercury is 0.002 mg/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 Mercury over the federal limit?
2 of the 66 public water systems on The Water Map report Mercury at or above its federal limit, spanning 12 U.S. states. The full list is on this page.
+How can I check if Mercury 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 Mercury.