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Contaminant guide

Mercury in drinking water

The EPA limit for Mercury in drinking water is 2 µg/L. Of the 33,727 water suppliers tested, 1,160 had it detected.

2 µg/L
EPA limit (MCL)
3.4%
of suppliers detected it
(1,160/33,727)

What Mercury is, and why it's regulated

Mercury enters water from natural deposits, refineries and runoff from cropland; it damages the kidneys.

What the EPA limit means

⚖️

2 µg/L

Maximum Contaminant Level — the enforceable ceiling a supplier must stay under.

🎯

2 µg/L

Health goal (MCLG) — the level with no known health effect. It is a goal, not a legal limit, and is often zero for carcinogens.

🧪

SYR4

Where these measurements come from. Hover the tag for the EPA programme and years.

Where Mercury was found

The water suppliers reporting the highest levels, worst first. For lead and copper that is the 90th-percentile result the action level is written against; for Six-Year Review data, the 95th percentile of each system's samples.

SupplierCityStateLevel vs EPA limit
Cal Am Water Company - Monterey Pacific Grove CA
41.28 µg/L 2064%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Pinehurst Manor East Earl PA
15 µg/L 750%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
June Lake Pud Village June Lake CA
9.1 µg/L 455%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Evergreen Estates Fairfield twp.-0605 NJ
7.58 µg/L 379%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Oro Valley Water Utility Oro Valley AZ
6.7 µg/L 335%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Bakersfield, City of Bakersfield CA
6.544 µg/L 327%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Sunrise Trailer Ct Lebanon PA
4 µg/L 200%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
South Claiborne Water System Athens LA
3.4 µg/L 170%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Lake Tarpon Mobile Home Villag Palm Harbor FL
3.1 µg/L 155%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Meadows Mobile Home Estates — VA
2.5 µg/L 125%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Cassatt Wtr Kershaw-Lee Co Rwa Cassatt SC
2.4 µg/L 120%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Knoll Enterprises Ludlow CA
2.365 µg/L 118%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Heritage Est Mobile Homes — PA
2.3 µg/L 115%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Western Greene County R W D Walcott AR
2.26 µg/L 113%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Murrieta/Hernandez Farms Kerman CA
2.2 µg/L 110%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Ransdell Mhp Bunn NC
2.2 µg/L 110%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Whittier-City, Water Dept. Whittier CA
2.2 µg/L 110%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Vineland Water & Sewer Utility Vineland city-0614 NJ
2.19 µg/L 110%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Picnic Grove Mobile Homes Pittsgrove twp.-1710 NJ
2.1 µg/L 105%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Greensboro, Town of Water Sys. Greensboro FL
2.1 µg/L 105%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Rancho Carrillo Mwc Rancho Mission Viejo CA
2.08 µg/L 104%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Cal/Am Water Company - San Marino Rosemead CA
2.01 µg/L 100%
of the EPA limit, at the 95th percentile of samples — 2 µg/L
Lower Lake County Water District Lower Lake CA
2 µg/L 100%
of the EPA limit 2 µg/L
Town of Hampstead Hampstead MD
1.91 µg/L 96%
of the EPA limit 2 µg/L
Great Oaks Wc Inc San Jose CA
1.9 µg/L 95%
of the EPA limit 2 µg/L

Frequently asked questions about Mercury

What is Mercury in drinking water?

Mercury enters water from natural deposits, refineries and runoff from cropland; it damages the kidneys.

What is the EPA limit for Mercury?

The EPA's Maximum Contaminant Level for Mercury is 2 µg/L, and its health goal (MCLG) is 2 µg/L. A result above the limit means the supplier must act; the goal is the level at which no health effects are expected.

How common is Mercury in US tap water?

Of the 33,727 water suppliers with results on file, 1,160 detected Mercury — 3.4% of those tested.