What arsenic level is safe in well water?

EPA sets 0.010 mg/L as the limit for public systems and uses zero as the health goal. Lower is better. If your result approaches or exceeds 0.010 mg/L, treat the water and consult your health department.

Does boiling remove arsenic?

No. Boiling does not remove arsenic and can slightly concentrate it as water evaporates. Use certified treatment or an alternate source.

Testing & SafetyHealth-sensitive topic

Arsenic in Well Water: Why and How to Test

Arsenic occurs naturally in some aquifers and has no taste, odor, or color. The only way to know your level is to test. The EPA limit is 0.010 mg/L.

By Know Your Well Water Editorial TeamReviewed October 26, 20263 min read

Quick Answer

Arsenic is a naturally occurring element found in elevated levels in some groundwater, with no taste, odor, or color. The EPA Maximum Contaminant Level for public water is 0.010 mg/L (10 µg/L); there is no corresponding automatic limit for private wells, but it is the standard reference point. Long-term exposure above this level is a recognized health concern, so if you live in an area with documented arsenic, test — and retest periodically, since levels can change.

Why test for arsenic

It is undetectable by sight, taste, or smell.
It is naturally present in some bedrock and alluvial aquifers (documented by USGS in parts of New England, the upper Midwest, and the West, among others).
Health risks are associated with long-term exposure, so chronic low-level presence matters.
Levels in a single well can vary over time, so one clean test is not a permanent guarantee.

How to test and read results

Use a state-certified laboratory and ask for total arsenic. Results are usually reported in mg/L or µg/L — 10 µg/L equals 0.010 mg/L. If arsenic is present, the laboratory or a water-treatment professional can determine the species (arsenic III vs. V), which affects which treatment is effective.

Units matter

Be careful converting between µg/L (ppb) and mg/L (ppm): 10 µg/L = 0.010 mg/L. Our Water Test Interpreter handles this conversion for you.

If arsenic is elevated

1Switch drinking and cooking water to a confirmed-safe source while you plan.
2Confirm the result and determine the arsenic species with the lab.
3Select treatment certified for arsenic removal for the species present (options include certain adsorptive media, reverse osmosis, and anion exchange).
4Retest after installation and on the maintenance schedule the system requires.

Not all filters remove arsenic

Standard carbon or sediment filters and water softeners do not reliably remove arsenic. Use a method certified for arsenic and the specific species in your water.

Frequently asked questions

What arsenic level is safe in well water?: EPA sets 0.010 mg/L as the limit for public systems and uses zero as the health goal. Lower is better. If your result approaches or exceeds 0.010 mg/L, treat the water and consult your health department.
Does boiling remove arsenic?: No. Boiling does not remove arsenic and can slightly concentrate it as water evaporates. Use certified treatment or an alternate source.

Sources & references

National Primary Drinking Water Regulations — US EPA, accessed October 26, 2026
Arsenic in Drinking Water — US EPA, accessed October 26, 2026
Private Ground Water Wells — CDC, accessed October 26, 2026

This guide is documentary research and general information, not a laboratory analysis or professional assessment of your specific well. See our disclaimer.