Radon in Water

We often hear about radon in air, since radon entering the home in gas form is the most prominent way for it to be a health hazard in our area. However, the presence of high radon concentrations in water can also be a health issue once the radon in the water is released into the air with normal usage. This can add to the overall radon in air concentration in the home. Read my Radon: Hazard Or Hype? article.

According to the EPA, “Some people who are exposed to radon in drinking water may have increased risk of getting cancer over the course of their lifetime, especially lung cancer”.

Radon is the 2^nd leading cause of lung cancer after smoking. Radon is an odor-less and taste-less radioactive gas that comes from the natural breakdown of uranium in the ground. Once it enters the home, radon can increase the chances of getting lung cancer for the home’s occupants. This risk is much higher for those who also smoke. While radon in air often enters the home through cracks or other openings in the home’s basement or crawl space floor and walls, radon in water most often enters the home when activities utilizing well water are occurring.

Think of running the shower with hot water. Water vapor is produced with a hot shower and once the hot water droplets strike an object, such as your body, small pockets of the radon gas within the water droplets are released into the air. The radon gas is then available for inhalation. During a typical washing machine cycle using hot water, studies show that approximately 98% of the radon in the water will be released, while 93% would be released for a cold water cycle. A hot shower would release approximately 72% of the radon in the water.

The beauty of using continuous radon monitors, as some home inspectors do, allows the graphical depiction of the home’s radon in air level over the course of 48 or more hours. A continuous radon monitor takes a radon measurement every hour and reports this data in tabular and graphical form. Radon levels in air can often be synchronized with water usage in a home served by a well. Having a graphical printout of the hour-by-hour radon levels can help determine if a radon in water issue occurs in a home, although this would normally only be done after a radon in air remediation system is installed. This is because, at least in our area, radon gas from the ground tends to be a much higher probability than from radon released from well water. If a radon in air remediation system was properly installed, however the home still had high radon levels and was served by well water, a radon in water test would often be the next step in the remediation process.

Many public water systems in our area actually get their water from wells, but they are required to test for radon and other contaminants regularly. Homes served by private wells rarely have their quality tested and may present an increased risk to those who drink the water.

There is an estimated 10,000:1 ratio for radon in water compared to radon in air. This means, that a radon in water concentration of 10,000 pCi/L (picoCuries per Liter) will typically cause a correlation of 1 pCi/L radon in air. On average, for a home with well water, less than 1% of the radon in air concentration comes from water.

Few testers of radon in water exist in our area as the demand for this service is rather low. The testing method is different for radon in water than for radon in air. A large amount of water is run into a container and a testing vial is then opened under the full bowl of running well water to ensure no air bubbles exist within the vial. The sample is then sent to a certified lab to be analyzed for radon in water.

Remediation of radon in water is possible using either of two methods: diffused bubble aeration or granulated activated charcoal. Either method would be installed at the point where the water service enters the home. Both methods can be rather expensive.

For further information about radon in water, please visit:

http://www.epa.gov/radon/rnwater.html

http://www.dep.state.pa.us/brp/Radon_Division/Radon_in_Water.htm

Please keep in mind that the testing for radon is outside the scope of a home inspection, although many home inspectors do offer radon testing as an add-on service. Radon testing in water, in south-central PA, is rarely done due to radon’s prevalence in air in our area.

Matthew Steger is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at matthew@thehomeinspectorsnotebook.com. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.