Date Published: 05/04/2020 [Source]
Radon can be found in ground water sources of drinking water (rather than surface waters, such as rivers, lakes and streams) in some parts of the United States. Radon is a naturally occurring radioactive breakdown product of uranium that can dissolve and accumulate in ground water. However, the primary source of human exposure to radon is breathing radon in indoor air of homes. Most of the risk from radon in drinking water (nearly 90 percent) comes from breathing radon released to indoor air from household water uses.
See EPA's web site for additional information on radon in drinking water: http://water.epa.gov/lawsregs/rulesregs/sdwa/radon/regulations.cfm