What is Radon?
Radon is a naturally-occurring radioactive gas that may cause cancer and may be found in drinking water and indoor air. Some people who are exposed to radon in drinking water may have an increased risk of getting cancer over the course of their lifetime, especially lung cancer. Radon in soil under homes is the biggest source of radon in indoor air and presents a greater risk of lung cancer than radon in drinking water. As required by the Safe Drinking Water Act, EPA has developed a proposed regulation to reduce radon in drinking water that has a multimedia mitigation option to reduce radon in indoor air.
As part of the Drinking Water and Health pages, this fact sheet is part of a larger U.S. EPA publication:EPA National Primary Drinking Water Regulations