--- title: Is Radon in Water Dangerous? canonical: "https://radonmitigationyorkpa.net/radon-guide/is-radon-in-water-dangerous/" pubDate: "2026-10-01T00:00:00.000Z" updatedDate: "2026-10-03T00:18:00.000Z" author: Radon Mitigation York PA description: "Most of the risk from radon in well water comes from breathing gas released in showers and laundry, not drinking it. Here is what the data shows." --- # Is Radon in Water Dangerous? [Untreated radon in well water](/services/radon-in-water-treatment/) can be dangerous, but mainly because of the air you breathe, not the water you drink. When you shower, wash dishes or do laundry, radon escapes from the water into your home's air and raises your lung cancer risk. Drinking radon-laden water carries a smaller risk, mostly to the stomach. ## Two ways radon in water reaches you Radon is a colorless, odorless radioactive gas. It forms as uranium breaks down in soil and rock, and it dissolves into groundwater. If your home is on a private well, that water can carry radon into your house. From there, it reaches you in two ways. ### Breathing it (the bigger risk) Radon comes out of water whenever the water is sprayed, heated or stirred. Showers, dishwashers, washing machines and running faucets all release it into the air. Once it is in the air, you breathe it in along with the radon that enters your home from the soil. Inside your lungs, radon and its decay products give off radiation that can damage lung tissue over time. EPA estimates radon causes about 21,000 lung cancer deaths a year in the U.S., and it is the leading cause of lung cancer among non-smokers. Most of that comes from soil gas, but radon released from water adds to the total. ### Drinking it (a smaller risk) When you drink water with radon in it, some of the radiation reaches the stomach before the gas leaves your body. The risk is real but smaller than the inhalation risk. ## What the numbers show When EPA proposed its radon in drinking water rule in 1999, it estimated radon in drinking water causes about 168 cancer deaths a year in the U.S. About 89% of those were lung cancers from breathing radon released from water, and about 11% were stomach cancers from drinking it. | Exposure route | Share of estimated deaths from radon in water | |---|---| | Breathing radon released from water | About 89% (lung cancer) | | Drinking water with radon | About 11% (stomach cancer) | Compare that with the roughly 21,000 deaths a year linked to radon overall. Radon from soil entering your home is the much larger problem for most families. That is why the first step for any York County home is an air test, and why a water test is the right second step for homes on private wells. ## How much radon in water is a concern? A common rule of thumb, repeated by PA DEP, is that 10,000 pCi/L of radon in water adds about 1 pCi/L to indoor air. So a well at 2,000 pCi/L adds only about 0.2 pCi/L to the air, while a well at 20,000 pCi/L adds about 2 pCi/L. There is no enforceable limit for private wells. EPA proposed 300 pCi/L for public water systems in 1999, with a 4,000 pCi/L alternative for places with indoor air programs, but that rule was never finalized. ## Is it safe to shower in water with radon? For most homes, an occasional shower is not an emergency. But showers are one of the biggest sources of radon release from water, and the air in a closed bathroom can briefly reach higher levels than the rest of the house. If your water radon is high, simple steps help while you plan treatment: - Run the bathroom exhaust fan during and after showers. - Keep showers shorter. - Open a window when weather allows. These steps reduce exposure but do not remove radon. Whole-house treatment at the point where water enters the home is the long-term fix. ## The first step: find out your number You cannot see, smell or taste radon, and there are no immediate symptoms. The only way to know is a lab test of your well water, taken the right way so the gas does not escape before it reaches the lab. Our guide on [how to test well water for radon](/radon-guide/how-to-test-well-water-for-radon/) walks through it step by step. EPA's [Citizen's Guide to Radon](https://www.epa.gov/sites/default/files/2016-12/documents/2016_a_citizens_guide_to_radon.pdf) covers air testing. ## Key takeaways - The main danger from radon in water is breathing radon released into the air. - EPA's 1999 estimate put about 89% of waterborne radon deaths in the lung cancer group and about 11% in stomach cancer. - Radon from soil is a larger source than water for most homes. - Test both your air and, if you have a well, your water. ## Frequently Asked Questions ### Is bottled water a fix for radon in well water? It cuts the drinking risk but not the bigger risk from breathing radon released by showers and laundry. Whole-house treatment addresses both. ### Is radon in city water a problem? It is less common. Water from rivers and reservoirs loses most of its radon to the open air before it reaches your tap. Private wells drawing from bedrock carry the most. ### Are there symptoms of radon exposure? No. Radon causes no immediate symptoms. The harm shows up as an increased lung cancer risk over many years, which is why testing matters. ## Get your water and air reviewed Worried about radon in your well? Call [(717) 356-3035](tel:+17173563035) any time for a same-day callback and a free written quote. We look at both your air and water results.