Radon is a radioactive gas that is formed naturally by the breakdown of uranium in soil, rock and water. Radon is colourless, odourless and tasteless. When Radon is released from the ground outside it mixes with fresh air and gets diluted resulting in concentrations too low to be of concern. However, when Radon enters an enclosed space, such as a house or basement, it can accumulate to high concentrations and become a health risk.
Radon gas can enter a house any place it finds an opening where the house contacts the soil: cracks in foundation walls and in floor slabs, construction joints, gaps around service pipes and support posts, floor drains and sumps, cavities inside walls, and the water supply.
Radon can also be found in groundwater from private or small community wells. Radon produced in the ground can dissolve and accumulate in water from underground sources such as wells. When water containing Radon is agitated during daily household use showering, clothes washing or cooking, for example, the Radon gas can be released into the air. However, research has shown that drinking water that contains Radon is far less harmful than breathing the gas. The health risk does not come from consuming the Radon, but from inhaling the gas. And in most cases, the risk of Radon entering the home through water is much lower than if it enters through the ground.
Almost all homes have some Radon. The levels can vary dramatically even between similar homes located next to each other. The amount of Radon in a home will depend on many factors. Because there are so many factors, it is not possible to predict the Radon level in a home; the only way to know for sure is to test.