Testing for Radon in Water

• Should drinking water be tested?
• What do the results of a water test mean?
• What levels of radon in water should I be concerned about?

Should drinking water be tested?

Because radon in indoor air is the larger health concern, the EPA recommends that you first test the air in your home for radon before testing for radon in your drinking water. the EPA and the Surgeon General recommend testing all homes for radon in indoor air (and apartments located below the third floor). The EPA recommends that you take action to reduce your home's indoor radon levels if your radon test result is 4 pCi/L or higher.

If you have tested the air in your home and found a radon problem, you may also want to find out whether your water is a concern. If you get water from a public water system, find out whether the comes from a surface (river, lake, or reservoir) or a ground water (underground) source.

If the water comes from a surface water source, most radon in the water will be released to the air before it reaches your tap. If the water comes from a ground water source, call your water system and ask if they've tested the water for radon. If so, ask for their Consumer Confidence Report.

If you have a private well, the EPA recommends testing your water for radon. The Safe Drinking Water Hotline, (800) 426-4791, can provide phone numbers for your state laboratory certification office. You can also call the National Radon Program Services Hotline, (800) SOS-RADON, for your state radon office's phone number. Your state laboratory certification office or state radon office can direct you to laboratories that are able to test your drinking water for radon.

What do the results of a water test mean?

Estimate how much the radon in your water is elevating your indoor radon level by subtracting 1 pCi/L from your indoor air radon level for every 10,000 pCi/L of radon that was found in your water. (For example: if you have 30,000 pCi/L of radon in your water, then 3 pCi/L of your indoor measurement may have come from radon in water.) If most of the radon is not coming from your water, fix your house first and then retest your indoor air to make sure that the source of elevated radon was not your private well. If a large contribution of the radon in your house is from your water, you may want to consider installing a special water treatment system to remove radon. the EPA recommends installing a water treatment system only when there is a proven radon problem in your water supply.

What levels of radon in water should I be concerned about?

EPA and various states have recommended drinking water standards for radon in water ranging from 300 to 10,000 pCi/L but no standard currently exists.  Check with your state radon program to determine if there are any guidelines or recommendations for taking action to reduce radon in water concentrations.