This information on naturally occurring radionuclides in drinking water has been prepared by the Massachusetts Drinking Water Program of the Department of Environmental Protection (MassDEP). It is intended to answer some of the most commonly asked questions concerning radionuclides in drinking water.

What are radionuclides and how do they get into drinking water?

Radionuclides are naturally occurring radioactive minerals that are occasionally present in bedrock, similar to other minerals such as iron, arsenic, and quartz. As ground water moves through fractures in bedrock that contains the mineral deposits, radioactive minerals can leach out into the groundwater system. Radionuclides dissolve easily in water.

Bedrock wells (often called artesian or drilled) can contain elevated concentrations of one or more radionuclides even if nearby bedrock wells have low concentrations. Wells that derive water from sand and gravel deposits, also known as dug or point wells (shallow wells), generally have substantially lower concentrations or no dissolved mineral activity.

Radionuclides exist throughout Massachusetts. In some areas the concentration of these minerals exceeds the public drinking water standards for radioactivity. The safety standards for the permissible amount of radioactivity in drinking water are called maximum contaminant levels (MCL).

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How can radionuclides affect my health?

The U.S. Environmental Protection Agency (EPA) sets drinking water standards and has determined that certain radioactive minerals above specified levels are a health concern. Exposure to radioactivity increases risk of developing various cancers. Other sources of radioactivity in the environment include X rays, radiation from the sun, foods from plants that concentrate radioactivity as they grow, fluorescent watch dials, and many other sources. At lower exposures, the risk of cancer is reduced. The principal health concerns associated with uranium is toxicity to the kidneys and radium is increased risk of bone cancer. Bathing and showering in water that contains uranium and radium is not a health concern.

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What are the health standards for radionuclides in drinking water?

EPA finalized new health standards for radionuclides in drinking water for public water systems in 2000. However, these standards only apply to community public water systems. There are currently no standards established for private wells (a well that serves less than 25 people) or other non-community public water systems (wells supplying schools, factories, shopping centers, etc.). The standards listed below are enforceable for all community public water systems and serve as guidelines for all other drinking water supplies.

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Do I have radionuclides in my water?

If you are served by a community public water system, you can contact the utility for specific information on radionuclides in your water. Consumer Confidence Reports (annual water quality reports) issued by the utility in early summer will also contain this information. If a standard is exceeded, the utility must notify customers.

If you have a private well constructed in bedrock, you must have the water tested to determine if radionuclides are present. The mineral radioactivity level of well water can vary substantially based on rainfall and other factors. Thus, at least two samples (taken a month or two apart, if possible) should be taken before conclusions are reached regarding the average concentration of any radionuclide. If the initial screening indicated little or no gross alpha particle activity, then there is little or no activity caused by radium 226, radium 228, and uranium; further testing is not necessary. If, on the other hand, elevated levels of gross alpha are detected, additional testing is suggested.

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Can radionuclides in drinking water be treated?

Yes. All naturally occurring radioactivity can be treated. However, different radionuclides require different types of treatment. In general, mineral radioactivity only needs to be removed from water that will be consumed or used in food. Some treatment systems intended and installed for the removal of hardness, iron, manganese and nitrates are also effective in reducing radionuclide levels and may inadvertently remove them at the same time. When only a very small amount of treated water is needed, reverse osmosis is likely the most economical water treatment method to remove dissolved mineral radioactivity. Ion exchange treatment will likely be more cost effective when larger amounts of treated water are needed.

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Who can I contact for more information?

For information on private well testing visit:
Web page
For a list of Massachusetts certified laboratories visit:
Web page
For questions about your public water system contact the system or visit the MassDEP Drinking Water Program Website:
Web page

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