Gross alpha radiation is a type of energy released when certain radioactive elements decay or break down. For example, uranium and thorium are two radioactive elements found naturally in the Earth’s crust. Over billions of years, these elements slowly change form and produce “decay products” such as radium and polonium. During this change process, energy is released. Gross alpha radiation is one form of the energy released. As a result, gross alpha radiation can be found in your drinking water.
Gross alpha radiation may cause health effects over time. Because gross alpha radiation loses energy rapidly and within a short distance, it does not pass through the skin. It is not a hazard outside of the body. However, the radiation can be harmful if you eat, drink or breathe in something containing gross alpha radiation.
Over a long period of time and at elevated levels, radium increases the risk of bone cancer and uranium increases the risk of kidney damage. There are no immediate health risks or symptoms from drinking water that contains gross alpha radiation.
Gross alpha radiation, uranium and radium can get into your drinking water if your well is drilled into or near bedrock containing radioactive elements. The amount of gross alpha radiation in water varies because the Earth’s bedrock contains varying amounts of radioactive elements. As radioactive elements decay, gross alpha radiation continues to be released into groundwater as positive ions called cations (for example, radium 226 and 228), negative ions called anions (for example, uranium), or as radiation with no charge.
You cannot see, smell or taste gross alpha radiation or radioactive elements. Testing is the only way to know if they are in your water. The Health Department recommends testing your private water source for gross alpha radiation and uranium every five years.
Levels of uranium and radium in drinking water are regulated by the Environmental Protection Agency (EPA) and the State of Vermont. However, there may be more radioactive elements in your water. To account for this remaining radioactivity, the gross alpha level is also regulated. Public water systems in Vermont must keep the gross alpha radiation at or below the following maximum contaminant levels (MCLs) at each entry point of their distribution system:
- Adjusted Gross Alpha = 15 pCi/L (picoCuries per liter)
- Combined radium 226/228 = 5 pCi/L
- Uranium = 0.020 mg/L (milligrams per liter)
Adjusted Gross Alpha (AGA) is a calculated value based on the gross alpha radiation and uranium result. If the AGA is above the MCL, the water system is notified, and a plan is made to find the source of the radiation and lower its level in the water. You can estimate the AGA in your water, if you have the results for gross alpha and uranium, by using the AGA Calculator.
For private well owners, the Health Department recommends testing for gross alpha radiation and uranium every five years and following these recommendations:
- If the AGA result is less than 5 pCi/L and the uranium result is less than 0.02 mg/L, no more testing or treatment is necessary. Retest again in five years.
- If the uranium result is above 0.02 mg/L, but the AGA result is less than 5 pCi/L, consider treating for uranium (for example, with reverse osmosis). Retest again in five years.
- If the AGA result is above 5 pCi/L, but the uranium result is less than 0.02 mg/L, the high AGA level is likely caused by radium. Consider treating for radium (for example, with a water softener), or testing for radium-226/228 to confirm the AGA level is due to radium and not other radioactive particles. Retest again in five years.
- If the AGA result is above 5 pCi/L, and the uranium result is above 0.02 mg/L, the high AGA level is likely caused by radium. Consider treating for uranium ( for example, with reverse osmosis) and radium (for example, with a water softener) or testing for radium-226/228 to confirm the AGA level is due to radium and not other radioactive particles. Retest again in five years.
Because gross alpha radiation causes cancer, any exposure to it will increase your risk of getting cancer. If you would like to lower or eliminate your exposure, consider treating your water for gross alpha radiation, even if it is under the MCL.
Order a gross alpha radiation screen (Kit RA) and uranium test (as part of Kit C or an individual uranium test kit) by calling the Health Department Laboratory at 802-338-4724 or 800-660-9997 (toll-free in Vermont). You can also use a certified drinking water lab to test for radioactive elements. The radium-226/228 test is not offered at the Health Department Laboratory, but can be ordered from a certified drinking water lab. Search for a certified drinking water lab
If your final result for uranium is more than (>) 0.020 mg/L, the level is over the health standard and treatment is recommended.
If your final result for radium is more than (>) 5 pCi/L, the level is over the health standard and treatment is recommended.
If your final result for adjusted gross alpha is more than (>) 15 pCi/L, the level is over the health standard and treatment is recommended.
Use the AGA Calculator to calculate radium and adjusted gross alpha.
Radioactive elements can be removed from drinking water. Your water may need to be treated for other water quality issues—such as hardness, iron, manganese and pH level—before it’s treated for radium or uranium. A water treatment professional will be able to determine which water treatment system is best for your water. Re-test for gross alpha radiation after any treatment system is installed to make sure levels are below the MCL. There are different treatments for different elements.
Reverse osmosis treatment addresses all gross alpha radiation contaminants. It uses a synthetic membrane that allows water to go through but leaves radium, uranium and other radioactive elements behind. The membrane is continually rinsed. It is usually installed under the kitchen sink (point-of-use or POU), but can also be installed as a whole house system (point-of-entry or POE). Install a system with a National Sanitation Foundation (NSF/ANSI) Standard 58 Certification. Search for an NSF/ANSI-certified reverse osmosis treatment system
Cation Exchange Treatment
A conventional water softener (also called a cation exchange softener) can be used to reduce the level of radioactive ions with a positive charge, like radium. This treatment exchanges radium for sodium or potassium, which remains in the water. The radium is flushed away with the wastewater when the softener is cleaned. This type of treatment is typically installed as a POE system.
Anion Exchange Treatment
Anion exchange is a treatment like water softening but uses a different media that exchanges the negatively charged radioactive ions, like uranium for chloride. This is also typically a POE system.
Vermont Wastewater and Potable Water Revolving Loan Fund
This program, also known as the On-Site Loan Program, is available to certain Vermont residents for the repair or replacement of failed water supply and on-site wastewater systems. The On-Site Loan Program is funded and administered by the Agency of Natural Resources, Department of Environmental Conservation with loan underwriting and servicing provided by the Opportunities Credit Union in Winooski. Your drinking water supply has to be a failed system and you must be living in the residence on a year-round basis to be eligible. The family income cannot exceed 200% of the state median household income. For more information about eligibility and how to apply, call the On-Site Loan Program at 802-461-6051.
The NeighborWorks Alliance of Vermont
The NeighborWorks Alliance is made up of five local organizations offering full affordable housing services for income-eligible individuals. You may qualify for help from this program if you need money to install a water treatment system, drill a well, or repair or replace your septic system. For more information on eligibility, contact the local NeighborWorks Group in your region.
Single Family Housing Repair Loans and Grants
This program offers loans and grants to existing homeowners for well construction, repair and sealing. It's administered by the Rural Development office of the U.S. Department of Agriculture. The program is for low-income families who live in a rural area or a community with a population of 25,000 or less. The family income cannot exceed 50% of the median county income. Individuals who are 62 years of age or older may qualify for a grant or a combination of a loan and a grant. Younger applicants are eligible only for loans.
Burlington, South Burlington, Essex Junction, Winooski and parts of Colchester are ineligible for the program. Even if your property is in an eligible area, your eligibility is still subject to income limits. For more information or to find out if your property is in an eligible area, call the USDA Rural Development Office at 802-828-6022.
Use the Adjusted Gross Alpha (AGA) Calculator
Download the gross alpha radiation fact sheet
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Find an NSF-certified home water treatment system