How Radon Gets into Your Home’s Water Supply

Radon in the soil doesn’t have to turn into gas. Instead, it can build up in wells and other underground water sources and can contaminate the water source. Similar to radon gas in the air, waterborne radon isn’t noticed unless tested.

So, when radon filled water makes its way into your water system and is being used for showering, cooking, drinking, and washing clothes and dishes; it can escape the water and enter into your home’s air. As long as the room that holds these water appliances is well-ventilated, it may be enough to prevent the radon from converting from the water into the air.

If your home’s water comes from an underground source, it's recommended to have the water tested for radon. However, not every underground water source will contain harmful levels of radon. But, it’s always safe to have your water tested, especially if your home’s airborne radon levels are high, and if your water is from an underground source.

History And Understanding Waterborne Radon

Safe water standards are in place to protect the public against the effects of hazardous water, even in those particular areas noted to show consistently high levels of waterborne radon. Such places include the Appalachian and Rockie Mountain ranges. It's also interesting to note that private water supplies test with higher waterborne radon levels in comparison to public supplies, most particularly in Florida, Georgia, Maine, Montana, Rhode Island and South Dakota. Unfortunately, New Englanders seem to maintain high levels of radon in both public and private water supplies.

Waterborne radon is not, however, a concern if the water is coming from lakes, rivers, or reservoirs-- only underground water sources are of concern. These surface water sources are likely to release the radon into the air before ever reaching your water. So what makes ground water so susceptible? Well, it's contained and concentrated. The same is true of airborne radon. The air everywhere has some traces of radon, but it becomes a problem when it enters into a home through its sublevels. Once inside the home, if trapped, it can become quite concentrated and even harmful.

So what's the standard for waterborne radon levels? The Conference of Radiation Control Directors, Inc. first asked that the EPA develop a water standard in 1986, but it wasn’t until 1991 that a rule was actually implemented.

Since radon is a proven carcinogen, the original maximum contaminant level (MCL) for waterborne radon had been set to zero. However, in 1992 congress asked for a reevaluation. In 1996 the alternative MCL (AMCL) was put in place. The EPA has worked closely with the National Academy of Sciences (NAS) to study risks and exposure rates, develop mitigation options, and evaluate their conclusions using scientific analysis.

The AMCL is no longer set at zero, but at a level that equals the average risk level assumed to be present from exposure to outdoor airborne radon. An AMCL is only accepted where a city or state is utilizing a multimedia mitigation plan otherwise known as, MMM.

If the waterborne radon level surpasses the MCL but falls below the AMCL, the EPA recommends having radon mitigation performed on the indoor air. This allows the focus to be on the more severe cancer causing situation—high radon levels within buildings.

Related Pages

• Waterborne Radon
• Reduce Radon in Water