Compared to radon entering the home through soil, radon entering the home through water will in most cases be a small source of risk.
Radon gas can enter the home through well water.
It can be released into the air you breathe when water is used for showering and other household uses. Research suggests that swallowing water with high radon levels may pose risks too, although risks from swallowing water containing radon are believed to be much lower than those from breathing air containing radon. While radon in water is not a problem in homes served by most public water supplies, it has been found in well water. If you've tested the air in your home and found a radon problem. If you're on a public water supply and are concerned that radon may be entering your home through the water, call your public water supplier.