Well Water Radon Testing
Radon in Water Testing for East Tennessee Wells
If your home runs on a private well, radon can come into your house through the water, not just through the soil. A simple lab test tells you whether it is a problem and what to do about it.
What Is Radon in Water?
Radon in water is radioactive radon gas that has dissolved into groundwater. It forms when uranium in rock and soil breaks down, and it dissolves into the water that moves through that ground. Private wells drawing from bedrock are the most common source of the problem.
When that water comes out of a faucet, shower, or washing machine, the dissolved gas is released into your indoor air. You can also swallow some by drinking the water. Most of the health risk comes from breathing the released gas, which is why water radon matters even if your air test looks fine.
East Tennessee sits on shale-rich, uranium-bearing geology, which is the same reason about 1 in 3 homes here test above the EPA action level in the air. Wells in that same ground can carry radon too.
Does My Home Need a Water Radon Test?
Testing makes sense if:
- Your home uses a private well, including a drilled well or a spring
- Your air radon test came back at or above 4.0 pCi/L
- You are buying a home with a well
- You have never tested your well water for radon
Tennessee's Division of Water Resources also recommends testing your private water supply for radon if your indoor air test is high.
If you are on a public water system, radon in water is usually much less of a concern, because the water is typically treated and aerated before it reaches you.
How Radon in Water Testing Works
Water radon is measured by a laboratory, not by a home test kit you leave sitting in a room. The sample has to be collected carefully so the gas does not escape before it is measured.
1. Collect the Sample
Water is drawn from a tap closest to the well, filled into a sealed vial with no air bubbles, and handled so radon does not escape.
2. Lab Analysis
The sealed sample goes to a laboratory, which measures radon in picocuries per liter (pCi/L) of water.
3. Understand the Result
We explain what the number means for your home and compare it with your indoor air results.
4. Decide on a Fix
If treatment is needed, we explain your options so you can choose with real information.
Why Test Your Well Water for Radon?
Radon in well water has no color, smell, or taste. The only way to know what is in your water is to test it, and it is one of the simplest things you can do to protect your family.
Nobody Else Is Testing Your Well
Public water systems are monitored. Private wells are not regulated by the EPA, so no one checks your water for radon unless you do. A simple lab test gives you a real number instead of a guess.
It Takes the Guesswork Out
Many East Tennessee homes sit on uranium-bearing rock, and wells drawing from that ground can carry radon. Testing is the only way to find out whether yours does, and many wells test just fine.
If It Is High, It Can Be Fixed
Proven treatment systems can remove radon from well water. Once you know your number, we explain your options so you can protect your home with confidence.
For the complete picture, test your indoor air too. See our Radon Testing Guide.
How High Is High? Reading Your Result
Water radon is measured in picocuries per liter (pCi/L). Here are the ranges commonly used to interpret a well water result, so you know what to expect before you test.
| Result | What it is called | What it generally means |
|---|---|---|
| Below 300 pCi/L | Lower | Little concern from drinking the water, and treatment is generally not needed. |
| 300 to 4,000 pCi/L | Slightly elevated | Treatment is optional, mainly for homeowners who want to lower their exposure. A carbon (GAC) system is often considered. |
| 4,000 to 10,000 pCi/L | High | Treatment is recommended. Either a whole-house carbon (GAC) system or an aeration system is typically used. |
| Above 10,000 pCi/L | Very high | An aeration system is recommended. It is also worth testing the water for uranium and radium. |
What It Means for Your Air
Radon released from water while you shower, wash dishes, or do laundry adds to your indoor air. As a rough estimate, about 10,000 pCi/L in the water raises indoor air by about 1 pCi/L. The EPA action level for indoor air is 4.0 pCi/L.
A Guide, Not a Law
The EPA proposed limits for public water in 1999 (300 pCi/L, or 4,000 pCi/L where a state has an approved indoor radon program) but never finalized them, and private wells are not regulated. These ranges are a practical guide, and we will help you apply them to your home.
If Your Well Water Is High: Treatment Options
Radon in water is treated at the point where water enters the house. The two common methods work very differently.
Aeration Systems
Water is sprayed or bubbled with air so the radon gas is released and vented outdoors. This is generally the more effective method and can remove the large majority of radon from the water. It needs a vent to the outside and some ongoing maintenance.
Granular Activated Carbon (GAC)
Water passes through a tank of carbon that traps radon. It is usually simpler and cheaper to install, and it works best on lower radon levels. The carbon can build up radioactivity over time, so tank placement and disposal need planning.
The right choice depends on your result, your water use, and your well. Cost depends on the system, so we quote after we see your results.
Frequently Asked Questions
Can radon be in well water?
Yes. Radon is a natural gas that forms from uranium in rock and soil and dissolves into groundwater. Private wells that draw from bedrock are the most likely to have it, and East Tennessee's geology makes testing worthwhile.
Is radon in water dangerous to drink?
Drinking water with radon carries some risk, but most of the health risk comes from breathing the radon that is released into indoor air when you shower, wash dishes, or run the washing machine.
How do you test water for radon?
A water sample is collected in a sealed vial with no air bubbles so the gas cannot escape, then sent to a laboratory for analysis. A home test kit left in a room measures air, not water.
What is a safe level of radon in water?
The EPA has not finalized a limit for radon in water. It proposed 300 pCi/L and described an alternative of 4,000 pCi/L for states with indoor air programs, and private wells are not regulated at all. That is exactly why testing matters: your lab result is the only way to know where your well stands, and we will help you read it.
What is a high level of radon in well water?
As a general guide, a result below 300 pCi/L is considered lower, 300 to 4,000 pCi/L is slightly elevated, 4,000 to 10,000 pCi/L is high and treatment is recommended, and above 10,000 pCi/L is very high and an aeration system is recommended. These ranges are guidance, not an EPA rule, and we will help you read your specific result.
If my water has radon, does my air test also need to be high?
Not necessarily. Soil gas and water radon are separate sources. As a rough estimate, about 10,000 pCi/L in water adds about 1 pCi/L to indoor air, so testing both gives you the full picture.
How do you remove radon from well water?
The two common methods are aeration, which releases the gas and vents it outside, and granular activated carbon, which traps it in a filter tank. Aeration is generally the more effective of the two.
Know What Is in Your Well Water
Request a water radon test from East Tennessee's NRPP-certified radon team, and we will walk you through the result.
Related reading: Radon in Water vs. Radon in Air and How Much Does Radon Mitigation Cost?