Is Radon in Home Water Supplies?
If radon gas can seep into your home through cracks in the foundation, sump pumps, and holes around floor joints, then can it also be in your drinking water?
Radon is formed from the decay of uranium in the soil and rocks around your home. Radon can enter water through the ground where it can dissolve into groundwater sources, such as wells. From there it can enter your home’s indoor air.
Household radon exposure from water is most commonly the result of it being released into the air during showering, doing laundry, washing dishes, cooking, toilet flushing, and other household tasks. When radon gas is released into the air it can be inhaled into the lungs where it decays into radioactive particles that damage the cells of the lung lining. Long term exposure to radon causes lung cancer. Radon can also remain in your tap water, where it can be ingested while drinking. In some cases, it has been linked to stomach cancer.
Municipal water vs. well water
Radon in water is not typically an issue in public/municipal water supplies. Radon in water becomes an issue when your water source is from an underground well.
When asked about radon in water, George Brozowski who is the EPA Region 6 Health Physicist/Radon Policy Advisor says that for people who have well-water he recommends testing their well for radon. If they are on city water, it’s not an issue, but he highly recommends that homeowners test their home for radon.
Research from the University of Georgia goes on to confirm that, “if you are served by a public water supply system sourced from groundwater, the risk is considered lower than that of a private well.”
Rural homes with groundwater wells
A new study from the University of Calgary has found that it is the presence of groundwater wells but not the water from those wells that contributes to higher radon problems in Canadian homes.
Their research from 42,000 long-term radon readings across Canada found that homes in rural communities have greater radon exposure than homes in urban areas. The link seems to be the proximity of rural homes to drilled groundwater wells versus urban areas that are on a municipal water supply.
Municipal water supplies in urban areas have a “shallow infrastructure” that pipes water into the home and wastewater out of the home whereas rural wells bring water in and out of the home from a hole much deeper in the ground. It is hypothesized that the space between the well water hole and the casing provides an easy route for radon gas in the soil to diffuse upwards to the ground surface.
This would then mean that radon isn’t entering a home from the water, but is instead emanating upward to the soil near the home from the water well hole.
Water vs. air radon concentration
Radon in your home’s indoor air resulting from radon in your water is highly variable. The amount of water used, water temperature, and the type of water use (such as showering vs. running water in a sink) can contribute to the amount of radon transfer from water.
According to Bryan Coy of 5280 Radon Mitigation in Denver, Colorado, “People should be concerned about radon in water. Radon in water concentrations can be so much higher than in the air.” Coy goes on to say that he recently saw a home's radon in water testing over 340,000 pCi/L and it was causing the radon in the air to go over 100 pCi/L. This home's water supply was from an underground well.
Radon mitigation
A home radon mitigation system is an effective solution for reducing the radon released into the air from water. In most cases, radon released into the air within your home poses the greater health risk versus exposure through drinking the water. Radon can be also removed from water using aeration treatment (such as an Airwell system) or granular activated carbon (GAC) treatment.
Begin by testing your home for radon. If you have elevated radon levels, hire a certified radon mitigator to install a radon system to bring the levels down. To find a certified radon mitigator in your area, contact the NRPP in the U.S. and the C-NRPP in Canada.