Radon is a naturally occurring radioactive gas and is found in air, water, soils, and rocks. It is formed by the breakdown of uranium into radon, which then decays to form the radon gas. Radon is a colorless, tasteless, and odorless gas. Its presence in the water is not indicated by any color, taste, or smell. Radon is measured in units of picocuries per liter (pCi/L). If radon is found in your well water, you must not ignore its presence as it can cause some severe health risks.
In this article, we will discuss how radon enters your well and home, what are the health risks, and how you can remove radon from your water.
How Radon enters your Water and Home?
Radon can enter your well from numerous sources. Radon is present in rocks and soils as a result of the decaying of radium. When water moves through these sources, it can dissolve in water and then pumped into your plumbing system. Radon is also produced as a result of manmade activates, but radon in water usually enters through natural sources such as rocks and soil.
Radon in homes also enters from the soil. The air pressure inside your home is less than the soil around your home. As a result of the air pressure difference, your home acts as an opening for the radon to move in your home. If your well water has radon in it, it can also be released in your home.
Maximum Contamination Level
U.S Environmental Protection Agency (EPA) is responsible for maintaining the safe levels of contaminants in drinking water. It is only entitled to look after the municipal water supplies. Well water users have to maintain the water quality themselves. The MCLs laid out by the EPA can be used by well water users to get an idea for maintaining water quality. EPA has set limits for different radionuclides in water, but currently, there is no standard set for radon. However, the EPA has given the states two options to ensure that private drinking water systems bring radon levels within the safe limit.
- For states that choose to follow the EPA’s Radon Mitigation Program (a program that strives to keep the radon levels inside the home below 0.4 pCi/L in the air), radon’s limit in drinking water is 4000pCi/L.
- For states which don’t want to follow the Radon Mitigation Program, the MCL for radon is 300 pCi/L. This concentration of radon will contribute around 0.03 pCi/L of radon to the air in your home.
All private well owners must check their state laws before choosing a removal method so that they can bring the radon level according to the state defined MCL.
Health Risks Posed by Radon in Drinking Water
Most of the health risks associated with radon are due to air contamination. Radon levels in the air can increase due to a high concentration of radon in water. Hence it is important to reduce the levels of radon in water according to the above-described limits. Radon causes thousands of deaths in the US every year. It is one of the main culprits for lung cancer, ranked only behind smoking. Around 180 people die in the U.S due to radon exposure. The majority of these deaths are due to radon in the air, which enters the home from well water. Radon in drinking water is also linked to the spread of stomach cancer.
Testing for Radon in Well Water
The only way to find out about radon in well water is to get it tested. You must contact a state-approved testing facility to perform the testing. Make sure you specifically ask them for a radon test as the general chemical screening does not include testing for radon. Be careful while collecting the sample and follow all the instructions given by the people at the lab. We suggest that you do not use any home testing kits for radon. Once you have the results in your hand, you can choose a filtration method to remove radon.
Removal Methods and Costs
Some people suggest installing a point of use filter for radon to get more effective results. It is not the best practice as radon must be removed before it can make entry into your home. Bathing in radon contaminated water poses a risk of inhaling radon for 15-20 minutes. Hence, all private well owners must install a point of entry (whole house treatment unit) to get rid of radon from well water. The following methods are the best for radon removal from well water.
Aeration is regarded to be the most effective way to remove radon from well water. It has the potential to remove up to 99.9% of radon in water and bring the concentration down to the safe level. When water is exposed to air, radon is removed from it. You may need to install a sediment filter before the aeration unit to remove the suspended particles from the water. There are three types of aeration units available. Let’s look at the details of each.
Spray Aeration – A spray aeration unit uses nozzles to spray water into a holding tank. During the spraying process, radon in the water is evaporated and is then removed through a vent. Make sure that the vent is not located in a closed space. You must vent it outside of your home. Spray aeration uses a number of spraying turns to capture radon. The first spray has the potential to remove up to 50% of the radon from water. Multiple sprays increase effectiveness. A spray aeration unit is attached to a water tank. You must choose the size of the tank according to your water needs.
Packed Column Aeration – A packed column uses a packing material to remove radon from the water. When the water enters from the top, it is sprayed on the packing material. A Clean air inlet at the bottom of the tank vents the radon outside of your home. The clean water is then carried to your home or storage tank. Please keep in mind that if the radon levels in your water are above 20,000 pCi/L, this unit will not work well. Another drawback of using this method is that hard water will cause scaling on the packing material, and it will, in turn, reduce the unit’s effectiveness.
Shallow Tray Aeration – A shallow tray aeration device is the most effective of all the aeration methods. It uses a tray with micro holes having air supply. When water is sprayed on these holes, the air in them removes radon from it. The water falls at the bottom of the unit and is then carried to your water storage tank. This unit takes more time to remove radon from water and uses more air to function. Hence its running cost is a bit high.
The cost of an aeration system starts around $2500. You will have to pay for installation, maintenance, and pay energy bills. Aeration units run on electrical energy so expect a slight increase in your electricity bill.
Aeration System and Radioactivity
The greatest advantage of using an aeration system is that they do not become radioactive over the years, and there is no risk associated while working with them. The radon removed from the water is released out of your home.
Aeration System and Water Quality
The aeration system tends to increase the pH of water by 0.5-1 point. This will not affect the water quality much. One problem with aeration units is that they have not been certified by the National Sanitary Foundation (NSF) or Water Quality Association (WQA). These organizations certify water filters and treatment units to ensure that their working is safe, and the water produced from them is safe to consume. You don’t need to worry about this as aeration units don’t add anything to your water other than air.
Granular Activated Carbon Filters
GAC filters are also used to remove radon from your well water. GAC filters remove radon through adsorption. When water moves through these filters, radon is collected on the carbon filter’s surface, and the resulting water is free from radon. Unlike aeration units, GAC filters’ effectiveness is dependent on the pH, temperature, chemical composition, and concentration of the contaminants. One disadvantage of using GAC filters is that it collects radon on top and needs to be handled by professionals during filter replacement and maintenance. If radon and other radionuclides are not present in your water, you can replace the filter yourself without any worries.
The GAC filters are cheap as compared to aeration units. A GAC filter can cost you around $300-$1000. The cost also depends upon the number of tanks and the number of filters. GAC filters need regular filter replacement as a part of the maintenance routine.
Other Ways to Get Radon-Free Drinking Water
If the above methods don’t work for you, you can do the following.
Connect to a Public Water Supply – Getting a public water supply connection is a nice way to get rid of all the worries of maintaining well water quality. However, there are some disadvantages compared to well water; you will have to pay for the water you use, city water continuity is vulnerable to natural disasters and infrastructural problems, and you will have to wait for years to get a connection.
Drilling a New Well – It must be kept as a last resort. There are high chances that the newly constructed well will have the same amount of radon in water. Hence, you must be very careful in this matter.