Radon can enter your home through your water supply, especially if you use well water. Radon is produced in the ground from trace amounts of uranium, the gas can travel great distances through porous soil and cracks in the rock. Radon dissolves in water and can contaminate your underground water supply. When radon enters your home through your water, it can raise the radon concentrations in your air whenever the water is used. Radon causes lung cancer.
Radon is second only to cigarette smoking as the leading cause of lung cancer death.
Both are preventable. Drinking water containing radon also presents a risk of developing internal organ cancers, primarily stomach cancer. However this risk is smaller than the risk of developing lung cancer from radon released to air from tap water. As you breathe, radon enter the lungs and continues its decay process. Each time a decay reaction occurs, the lungs' cells receive a small burst of radiation which, can damage the lung tissue or can cause the cells to mutate and develop into lung cancer.