Guide · Updated November 1, 2026

Mercury in Well Water: Limits, Testing and Results

Short answer: EPA's limit for inorganic mercury in public water is 0.002 mg/L (2 µg/L). Health Canada's maximum is 0.001 mg/L (1 µg/L) for all forms.

Where it is found

Health Canada says mercury is generally not found in drinking water because it binds to soil and sediment, but lists industrial releases, waste disposal and drainage of areas where pesticides were used as sources. New Jersey requires mercury testing in home sales in nine southern counties. State data (2002–2024) show 2.6% of tested wells in Camden County and 1.9% in Atlantic County exceeded 2 µg/L. See the New Jersey county pages.

How to test

Ask for mercury by EPA method 245.1 (cold vapor). It is not always part of a basic metals panel.

What results mean

Below 1–2 µg/L: under the limits. Above: retest to confirm and ask your local health department about options. Point-of-use treatment such as activated carbon or reverse osmosis is often used; check the device certification.

Sources

Questions

What is the limit for mercury in well water?

There's no federal rule for private wells. The public water limit EPA uses is 2 µg/L (0.002 mg/L). Health Canada's guideline is 1 µg/L.

Does a standard metals test include mercury?

Often not. Ask for mercury by EPA method 245.1.

Where are wells with mercury found?

In New Jersey, state testing found exceedances mostly in southern coastal plain counties, which is why the state requires the test there.

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