Radon is a gas that has no color, odor, or taste and comes from the natural radioactive breakdown of uranium in the ground. You can be exposed to radon through air and water. Radon is also found in small amounts in outdoor air. Most of the radon in indoor air comes from soil underneath the home. Radon gas can dissolve and accumulate in ground water entering wells. When water that contains radon is used in the home for showering, washing dishes, and cooking, radon gas escapes from the water and goes into the air. Some radon also stays in the water.

Radon is not a concern in water that comes from lakes, rivers, and reservoirs (called surface water), because the radon is released into the air before it ever arrives at your tap. If radon is present in your drinking water, test the air in your home as well. Consider treatment for your well water if the radon from the water is causing the level of radon in the air in your home to rise above the recommended indoor air action level of 4 pCi/L. It generally takes 10,000 pCi/L in water to increase the radon level in air by 1.0 pCi/L.

Only about 1-2 percent of radon in the air comes from drinking water. However breathing radon increases the risk of lung cancer over the course of your lifetime. Some radon stays in the water; drinking water containing radon also presents a risk of developing internal organ cancers, primarily stomach cancer. However this risk is smaller than the risk of developing lung cancer from radon released to air from tap water.

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Radon levels were detected in your water sample. There is currently no federally-enforced drinking water standard for radon.

Major sources in drinking water: 
A natural product of radioactive decay of uranium
Treatment options: 

The most effective treatment you can apply is to remove radon from the water right before it enters your home. This is called point-of-entry treatment.

  • Aeration: Aeration removes radon from water. In this treatment method, large volumes of air are blown through the water or the water is sprayed so that it is exposed to the air. In this way, the radon gas leaves the water and enters the air. The air is vented outside, and the treated water is repressurized and piped to faucets.
  • Granular activated carbon (GAC) filters: GAC filters tend to cost less than aeration devices, however, radioactivity collects on the filter, which may cause a handling hazard and require special disposal methods for the filter.
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