Updated November 2026 · Sources
Most radon in homes comes from the soil, but radon can also enter through water from a private well or a public system that uses ground water. When you shower, wash dishes or do laundry, radon escapes from the water into the air you breathe.
How risky is radon in water?
- Radon in water poses both an inhalation risk and an ingestion risk, but research shows the lung cancer risk from breathing radon is much larger than the stomach cancer risk from swallowing it (EPA).
- Most of the risk from radon in water comes from radon released into the air during household water use.
- Radon in water is not usually a problem when the source is surface water (lakes and rivers).
When to test your well
- If you have tested the air in your home and found a radon problem, and your water comes from a well, have your water tested (EPA).
- If you are on a public water system that uses ground water, ask your water supplier about radon.
- Radon-in-water test kits are a separate kit from air tests; some state programs sell them, for example the University of Georgia program lists water kits for $30.
How radon is removed from water
| Method | What it does |
|---|---|
| Point-of-entry treatment (aeration or granular activated carbon) | Removes radon from the water before it enters the home; treats all water used in the house |
| Point-of-use devices (at a single tap) | Treat only a small share of the water; not effective against radon released into the air from other water use |
For drinking water questions, the EPA’s Safe Drinking Water Hotline is (800) 426-4791. Your state radon program can also help with private wells.
Frequently asked questions
Can radon in well water cause cancer?
Radon released from water into indoor air adds to your lung cancer risk, and swallowing it carries a smaller stomach cancer risk, according to the EPA.
Should I test my well for radon?
Yes, if you found high radon in the air and your water comes from a private well, the EPA recommends testing the water.
Does boiling water remove radon?
Boiling releases radon into the indoor air, so it does not solve the problem. Point-of-entry treatment is the method the EPA describes for whole-house water.