How to Test Water for Radon
To test water for radon, collect a sample exactly as the lab or kit instructs and send it to a lab that analyzes radon in water. Keep the sample sealed and avoid splashing or shaking, because radon can escape from water into the air.
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To test water for radon, send a carefully collected water sample to a lab that specifically analyzes radon in water. Use the lab's container and instructions, and keep the sample sealed so dissolved radon has less chance to escape before analysis.
A water test for radon is different from testing indoor air. A short-term charcoal kit or other room test measures radon in air; it cannot tell you how much radon is dissolved in a tap or well water sample.
How do you test water for radon?
Choose a lab that accepts water samples for radon, then collect and return the sample as directed. The lab may provide a bottle, handling steps, and a deadline for delivery.
Before ordering a kit or collecting water, confirm:
- The test is for radon in water, not indoor air.
- Which tap or source to sample, and whether the lab requires any preparation.
- The required container, fill level, and cap.
- How soon the sample must reach the lab.
- Whether shipping and analysis are included.
Don't assume that a generic radon detector can test water. The sample method and lab analysis must be designed for dissolved radon.
How should you collect a water sample?
Follow the lab's directions exactly and minimize splashing, pouring, and open-air exposure. Radon can move from water into the surrounding air, so careful handling matters.
Use only the container specified for the test. If the lab says to run the tap first, use a gentle flow and avoid spraying water into the sink; if it gives a different procedure, follow that instead.
Fill and close the container as directed. Don't rinse, transfer, shake, or leave the sample open unless the instructions specifically require it.
Keep the sample in the conditions and for the time stated by the lab. Return it promptly using the provided shipping or drop-off instructions, since delays can affect whether the lab can analyze it.
What if you use well water?
Ask the lab whether it has a separate procedure for a private well sample. The correct sampling point may depend on the well system and the lab's method.
A radon test kit for well water guide can help you compare water-specific options and understand what the kit is intended to measure. Don't use an indoor air kit as a substitute.
How do you choose a radon water test kit?
Choose a kit only when its instructions clearly state that it tests water for radon. Confirm who analyzes the sample, what container is needed, and how results are delivered.
A radon water test kit should be matched to your water source and the lab's sample requirements. Check whether the test is for water alone or part of a broader water analysis, and read the return instructions before opening the kit.
Do not treat a kit's name or general radon wording as proof it tests water. The products below are indoor air radon test kits, based on their stated use, so they are not substitutes for a water test.
The First Alert kit is intended for radon gas measurement in a home or other indoor space. Its results can inform an indoor air check, but it does not measure radon dissolved in a water sample.
The PRO-LAB kit collects an air sample over a 48-hour period for laboratory analysis. Use it for indoor screening only, and choose a water-specific lab process for a faucet or well sample.
The Leaping Lynx kit is described for short-term indoor air screening, with a 48-hour collection period. It does not replace a water sample test.
For more on an indoor test, see How to Test for Radon at Home: A Quick Guide. A long-term radon test also checks indoor air over a longer period, not dissolved radon in water.
What does a water radon result tell you?
A water result describes the sample tested, not automatically the radon level in your indoor air. If the lab reports a high or unclear result, ask what the units mean and what next step it recommends for your water source.
For help understanding the report, see how to read radon test results.
Radon in water can be released into indoor air during everyday water use, but a water test alone doesn't show the room's air concentration. See when radon testing is necessary for situations that call for a separate home test.
If you want to assess exposure in the home, consider a separate indoor air test and follow its placement and timing instructions. For a multi-unit home, see radon testing in apartments.
Keep the lab report with the sample date and source. If you test again after changing equipment or treatment, use the lab's guidance so results can be compared sensibly.
What should you do after testing water?
Use the lab's interpretation and speak with a local health department or qualified water treatment professional about next steps. The right response depends on the result, water source, and system.
Don't boil water as a radon fix. Heating or aerating it can release radon into indoor air; get advice before changing how you use or treat the water.
If the report raises concerns about indoor exposure, test the air separately. Water and air tests answer different questions, so keep their results distinct when discussing options with a professional.
How to test water for radon: what is the next step?
To test water for radon, start with a lab or kit that explicitly accepts water samples, then follow its collection and return instructions. If you have well water, confirm the sampling point with the lab before collecting.
Use an indoor kit only to screen indoor air. Choose a water test for the dissolved radon question, and ask a qualified local professional to explain results and treatment choices.
Frequently asked questions
Can I use a home radon kit to test water?
Only if the kit and its laboratory instructions specifically say they test water for radon. A kit made to measure radon in indoor air does not measure dissolved radon in a water sample, even if it is sold as a home radon test kit.
Check the sample type before you buy or collect anything.
How do I collect a water sample for radon?
Follow the lab's exact container and collection steps, since a water sample can lose radon when it is poured, splashed, or left open. Many labs provide a container and instructions.
Avoid transferring the sample to another bottle, and return it within the lab's stated time window.
Does boiling water remove radon?
Heating or aerating water can release radon into indoor air, so don't use boiling as a home treatment based on a test result. Ask your local health department or a qualified water treatment professional about options for your water source and test result.
Should I test well water for radon?
If your home uses well water and you want to know whether it contains radon, ask a state-certified or otherwise qualified lab about a water-specific test. A private well water test for radon is separate from an indoor air radon test, so consider whether both questions matter for your home.
