Maximum Contaminant Level


MCL – 5 pCi/L

MCLG – zero

WHO Guideline – 0.01 mg/L

Radon Zones by Geographic Location1

Radon is a colorless, tasteless, odorless, radioactive gas. It occurs naturally and is produced by the breakdown of uranium in soil, rock, and water. It is the second highest cause of lung cancer after smoking, causing an estimated 14,000 lung cancer deaths per year. Radon in soil under homes presents a greater risk of lung cancer than the amount present in drinking water. Radon can enter into our water supply when natural deposits dissolve into groundwater; and then it is released into the air when you turn on a faucet.

1. United States Environmental Protection Agency. Secondary Drinking Water Standards: Guidance for Nuisance Chemicals. EPA.gov. [Online] January 6, 2016. https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals#how-can-correct.