To test well water for radon, contact the EPA's Safe Drinking Water Hotline or a state water certification authority. The EPA and state authorities both maintain lists of laboratories that perform radon testing on drinking water. Neither the EPA nor the CDC recommend at-home radon testing.
There is no need for individuals without private wells to test water for radon. Public water systems that draw water from rivers, lakes or reservoirs are safe from radon contamination. Surface bodies of water release radon into the air, so these water systems are naturally low in radon. Public water systems that draw from groundwater are tested for radon, and these results can be accessed by contacting local water utilities.
Well water high in radon can be decontaminated in two ways: aeration and filtration. Filtration systems use activated carbon to remove radon from water as it enters the home. Aeration systems mixes air with the water to remove radon. Radon gas dissolved in the water vents out through an exhaust fan along with the added air.
Filtration systems are cheaper but may pose a minor radioactive hazard. Radon collects in the charcoal filter, which must be periodically be changed. Used filters are hazardous to handle and require special disposal methods. Aeration systems avoid these hazards by directly venting radon gas instead of collecting it in a filter, but they are more expensive to purchase and install.