Radon can enter homes through their water systems. Homes served by private domestic wells and small public waterworks using ground water can be particularly vulnerable. Exposure to radon has been recognized as a health risk, primarily as a cause of lung cancer. One pathway by which radon can enter a home is through its water system, especially if ground water is the water source. Small public water systems and private domestic wells often have closed systems and short transit times that do not remove radon from water or permit it to decay.
Exposures can occur from water used for drinking, showering, and other common household purposes.
Radon gas also can enter buildings from surrounding rock and soil through foundation cracks. Radon levels are greater in the Springfield Plateau aquifer and the unconfined part of the Ozark aquifer than in the confined part of the Ozark aquifer. Hydrogeology appears be significant in determining radon levels. Radon levels are lowest in the confined part of the Ozark aquifer.