- What is uranium?
- How might I be exposed to uranium?
- What is the drinking water standard for uranium?
- How would I know if my drinking water contains uranium?
- What are the health concerns relating to uranium in drinking water?
- What type of treatment will decrease uranium in well water?
- Where can I get more information?
What is uranium?
Uranium is a radioactive element found in nature. It can be present in soil, air, water, rocks, plants and food. Uranium breaks down (decays) very slowly into other elements including radium and radon gas.
How might I be exposed to uranium?
In areas where uranium is present in rocks or soil, a drinking-water well can become contaminated with uranium. This can occur when the uranium in the surrounding rock or soil dissolves into the well water. Although western states are better known for having higher than average background levels of uranium in drinking water, uranium contamination of drinking water also can occur in Vermont.
What is the drinking water standard for uranium?
The U.S. Environmental Protection Agency sets the upper limit for uranium in community public wells at 30 micrograms per liter (µg/L), effective in December, 2003. The Vermont Department of Environmental Conservation’s Water Supply Division, however, has adopted a stricter, more health-protective standard for Vermont’s community wells of 20 micrograms per liter (µg/L).
How would I know if my drinking water contains uranium?
Community public water systems are required to test their water for radioactivity using an alpha radiation screen. Because the levels of radiation in the water can vary, four tests are performed throughout the year. If the results average 10 pCi/L (picocuries per liter) or more, the water is tested for uranium. Test results are available in the water system’s annual Consumer Confidence Report.
If you own a private well, you will need to test your drinking water if you wish to determine whether it contains uranium. As an initial test, we recommend an alpha radiation screen. This test will determine whether your water contains any radioactive elements. If the result of an alpha radiation screen is 15 pCi/liter or greater, we recommend that a uranium test and the radium tests be performed. You may purchase test kits from the Vermont Department of Health Laboratory. Prices vary depending on the type of test.
What are the health concerns relating to uranium in drinking water?
Most ingested uranium is eliminated from the body. However, a small amount is absorbed and carried through the bloodstream and into the kidneys. Studies show that elevated levels of uranium in drinking water can increase a person’s risk of kidney damage.
Over time, drinking water that contains uranium can increase a person’s lifetime risk of cancer. The amount of increased risk depends on the concentration of radioactivity found in the drinking water, the amount of water consumed on a daily basis, and the length of time one has consumed the water.
What type of treatment will decrease uranium in well water?
The Environmental Protection Agency has established a maximum contaminant level for uranium in public water systems of 30 µg/L (micrograms per liter). Because uranium levels can vary from season to season, homeowners should treat well water that has a uranium level equal to or greater than 20 pCi/L, which is approximately equal to 20 µg/L. Uranium can be removed from drinking water by several treatment methods. The two most common methods for homeowners are anion exchange and reverse osmosis.
- Anion exchange is a treatment system in which the well water flows through a tank with a resin that "exchanges" uranium for a safer compound—in most cases, chloride. Periodically, a backwash pump flushes the uranium and other wastes away from the resin into the household wastewater. The clean and recharged resin is then put back into service.
- Reverse osmosis is a treatment that uses a semi-permeable membrane to capture any uranium in the water. The device uses water pressure as a force against the membrane, and only water is able to pass through, which leaves the uranium behind. The membrane is continually rinsed. The rinse water containing uranium is discarded. This method of treatment can be slow and uses several gallons of water for each gallon of household drinking water produced.
Both anion exchange and reverse osmosis require that the treatment device be properly maintained and operated. Other water quality factors may determine which method is the best choice for treatment. Special wastewater disposal precautions may be necessary in some instances.
Public community water systems have the additional options of reducing uranium using lime softening or enhanced coagulation with filtration. These choices are not appropriate for a home treatment system. Other alternatives include blending in water from other wells to reduce overall concentration or, when feasible, connecting to a public system.