How to Test for Radon in Water

🤝 Our content is written by humans, not AI robots. Learn More

If your drinking water comes from a groundwater supply, you’re wise to be concerned about radon exposure.

The EPA estimates that the average concentration of radon in U.S. groundwater is 200-600 pCi per liter, but a UGA Extension resource reports that the average concentration from granite aquifers may exceed 8,000 pCi per liter – well above the EPA’s proposed MCL of 300 pCi/L.

Our water treatment experts have tried all the current methods of testing for radon in water, and in this guide, we’ve shared the top radon testing methods that we recommend.

How to Test for Radon in Water

🧪 Certified Laboratory Testing

Radon laboratory tests provide a detailed and comprehensive analysis of radon in water.

Lab testing is also currently the only way to detect radon in your water system. Test kits for at-home-DIY use for radon in water specifically (not air) are unavailable due to the complexity of the radon testing process.

Most labs will send you a testing kit containing instructions and vials for taking a sample from your water supply. You’ll then ship your sample to the lab, and they’ll test your water’s radon levels. The levels of radon detected will be noted on your testing report.

Here’s how to take a sample of your water for laboratory radon testing:

  1. Buy your preferred radon lab test and wait for the sample-taking kit to be mailed to your home.
  2. Unbox the kit and carefully read the instructions provided. Different kits may have specific requirements!
  3. Wash your hands or put on a pair of protective gloves (if provided).
  4. If the kit instructions recommend it, let the water run for a few minutes.
  5. Open the sample container provided in the kit and hold it beneath the running tap until it fills to the indicated level.
  6. Cap the container and return it to the sample kit box, then fill out any paperwork and mail it back to the laboratory as soon as possible.
  7. Wait for the laboratory to test your water and return your results (typically via email).
tap score water testing
Tap score sampling kit

Good to Know: Most lab tests for radon deliver results within 7-10 days, depending on the testing method used.

Dozens of state-certified laboratories offer radon water testing. We personally use Tap Score by SimpleLab. The Radon Water Test costs just over $100 and tests specifically for radon in drinking water. The Extended Well Water Test is a good option if you want to test for radon and other contaminants in your private well.

You can call the National Radon Program Services Hotline at (800) SOS-RADON to get the phone number for your state radon office, or call the Safe Drinking Water Hotline at (800) 426-4791 to obtain contact information for your state laboratory certification office. Both of these resources can help you find local labs that test for radon in water.

water testing with tap score

Our Top Tips for Taking a Radon Sample

To ensure you obtain accurate results from a laboratory drinking water radon test, there are a few things you should do when taking your water sample:

  1. Run your water for a few minutes (ideally at least 10), so the water is coming from the source and isn’t the water that was standing in your pipes.
  2. Use untreated tap water that has come straight from the source, without interception by a reverse osmosis system, a water softener, or an aeration system.
  3. Run the water slowly from the faucet, aiming to avoid agitating the water and producing any air bubbles.
  4. Return your sealed sample on the same day you collected the kit. The sample should be returned to the lab within 2 days of taking it.
Tips for Taking a Radon Sample

Methods of Laboratory Testing for Radon

There are a few different methods that laboratories use to detect radon in water. These include:

Liquid Scintillation

Liquid scintillation involves mixing a water sample with a scintillation cocktail, then using liquid scintillation counters to measure the emitted radiation, including alpha particles from radon decay. This sensitive method is widely used in laboratories to take accurate radon measurements in water.


Emanation is another common method that involves using a solid-state detector to trap radon gas released from water. The testing begins by exposing the detector to gas from the water for a specified period. Scientists can then analyze the detector to get a reading of the radon concentration. This method is less common than liquid scintillation but still widely used for radon testing in water.

Alpha-Track Detectors

Alpha-track detectors use a small piece of plastic that records damage caused by alpha particles emitted by radon and its decay products. After the plastic is exposed to the water sample, it’s sent to a laboratory for analysis, and the recorded damage helps scientists to determine the level of radon present.

📝 Interpreting Your Results

If results show that your water contains more than 300 pCi/L of radon, you can decide how to take action.

Why is it important to remove radon from your water?

A report from the International Journal of Epidemiology says that drinking water containing radon gas poses a risk of certain cancers, especially cancer of the stomach. The EPA estimates that around 168 people die from stomach cancer per year, caused by drinking radon in their water.

But radon gas is even more dangerous when you breathe it in.

According to the EPA, breathing in radon in indoor air can cause lung cancer. Radioactive gas from the air can build up in your lungs, releasing energy as it breaks down, damaging your lungs and increasing your risk of lung cancer.

Radon in indoor air is estimated to be the second leading cause of lung cancer, and some 20,000 people in the US die every year from breathing in radon.

In most scenarios, you won’t be able to prevent radon from contaminating your water. However, you can address radon in drinking water to avoid exposure to the gas in your home.

The best treatment options to reduce radon or remove radon from your water are:

  • Granular activated carbon filters – These remove and retain dissolved radon particles by adsorption. We recommend using whole-home system to prevent radon from getting into the air when you shower or use a water-based appliance. Note: GAC filters require special disposal methods when used to trap radon.
  • Aeration systems – These remove dissolved radon by introducing air into the source water. When exposed to this additional air, radon gas will naturally be released from the water into the aeration tank. The tank will then exhaust the air, where it will be vented to the atmosphere.
carbon water filter

📑 Final Word

Hopefully, this guide has provided the information you were looking for about testing for radon in your water.

Not all drinking water contains radon. Water might carry radon gas that gets released into the air before it reaches your home, so your risk of breathing radon in indoor air is very low.

But if you get your water from a ground water source (such as a private well), there’s no opportunity for the radon to escape into outdoor air, meaning that there’s a higher risk of radon contamination in your drinking water.

Granular activated carbon filtration and aeration can both effectively reduce radon levels in your water system. Make sure to address radon contamination with a suitable water treatment system as soon as possible.

  • Michael Claybourn
    Water Treatment Specialist

    With 25+ years in water treatment, Michael Claybourn Sr. (WT Specialist 3) leads his company, Water of Texas LLC, in solving industrial, commercial, and residential water challenges. From filtration to ozone, he tackles any task, from initial consultation to equipment maintenance. His passion, honed in nuclear power and Culligan of Brazosport, fuels his commitment to delivering pure, healthy water for every client.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top