Since radon gas is found in most soil and rocks, it is not only able to move into the air, but also into underground water sources.[111] Radon may be present in well water and can be released into the air in homes when water is used for showering and other household uses.[2] If it is suspected that a private well or drinking water may be affected by radon, the National Radon Program Services Hotline at 1-800-SOS-RADON can be contacted for information regarding state radon office phone numbers. State radon offices can provide additional resources, such as local laboratories that can test water for radon.[108]