Radium in Well Water
- Last Updated: 2.10.16
Anne Arundel County conducted a pilot study of well water quality from September 1997 to March 1998. During the pilot study, naturally occurring radium was found in 22 wells in northern Anne Arundel County. Fifteen of these wells exceeded the level established by the U.S. Environmental Protection Agency for public drinking water supplies. A larger study, conducted by the Maryland Department of the Environment in 1998, confirmed the presence of naturally occurring radium in groundwater in northern Anne Arundel County. Radium in drinking water does not pose a health emergency and can be effectively removed by installing a deeper well or through water treatment.
Since March 1, 2002, new and replacement wells in northern Anne Arundel County must be installed to a minimum well depth and meet drinking water standards for radium. The minimum well depth is determined based on the results of a computer model showing the distribution of radium data, well depths, property elevations and deep test wells. The minimum well depths in this area range from 250 to 500 feet.
Owners of existing private wells in northern Anne Arundel County (see map) (PDF) are encouraged to test for radium. The results of testing indicate two out of every three wells exceed the drinking water standard for radium. Where radium levels test high, well replacement or a water treatment unit is recommended.
What is radium?
Radium is a radioactive metal that occurs naturally in trace amounts in rocks and soils. As radium decays, it continually releases energy into the environment until a stable, nonradioactive substance is formed. This energy becomes part of the natural background radiation to which all living creatures are exposed. Radium also readily dissolves in groundwater where acidic conditions (low pH levels) are found. Various forms of naturally occurring radium have been found in the groundwater of Anne Arundel County, including radium 224, 226 and 228.
What is radioactivity and how is it measured?
Radioactivity is a natural decay process. Radioactive substances such as radium emit energy to reach a more stable condition. Scientists are able to identify the type and amount of radioactive substances in water by measuring the type and duration of the radiation emitted. The unit typically used to describe the amount of radioactivity present in drinking water is the picocurie per liter (pCi/l).
A screening test known as a short-term gross alpha test is the first step in detecting the presence of radium in drinking water. Alpha particles are a form of energy released through the decay of radium 224 and 226. Finding gross alpha particles in the water indicates the presence of radioactive substances, including radium 224 and 226.
What is the drinking water standard for radium?
A drinking water standard, or maximum contaminant level (MCL), is the maximum permissible level of a contaminant that is allowed in drinking water. This level is based on protection of human health but also takes into consideration feasible treatment technologies and monitoring capabilities. A value above the MCL does not indicate that harmful effects will occur, but that a risk exists and should be evaluated. The MCL for gross alpha particles is 15 pCi/l. The MCL for combined radium 226 and 228 is 5 pCi/l. There is no MCL for radium 224. There are no regulations that require private owners of existing private wells to meet the MCLs for water quality.
How can radium affect my health?
Particles of radioactivity from radium can be swallowed. Most of these particles are naturally excreted in feces or urine, but a small amount of radium can attach to bones. Swallowing radium can increase a person's risk of bone cancer. However, the relationship between the amount of water you drink with radium in it and its potential for causing cancer is not well documented. The rates of bone cancer in Anne Arundel County are the same as the overall rates for the United States. Risk studies conducted by the U.S. Environmental Protection Agency and the Maryland Department of the Environment estimate that if 10,000 people were to consume 2 liters of drinking water containing 5 pCi/l of radium every day over a 50 year period, one additional fatal cancer might occur in that group. It is also assumed that as the level of radium increases, so does the risk. For every 5 pCi/l increase in radium levels an estimated one additional fatality may occur. The risk associated with drinking water containing 5 pCi/l of radium for one year is comparable to one chest X-ray or five round trip flights from Maryland to California.
If elevated short-term gross alpha or radium levels are found in my drinking water, what can I do?
The Anne Arundel County Department of Health Well Water Program staff is available at 410-222-7398 to consult with you on water testing, water treatment and well replacement options.
Well owners may choose to install a replacement well or water treatment unit to remove radium. A replacement well must be dug to a depth where acceptable radium concentrations have been found. If well replacement is too costly, a water treatment unit is an alternative. Radium behaves in water similarly to calcium and magnesium, so water softening units, such as ion exchange, lime softening, reverse osmosis or distillation, are effective in reducing elevated levels of radium in drinking water. Before choosing a water treatment system, contact a water treatment company listed under water filtration and purification equipment in the Yellow Pages or contact the Department of Health. The Department does not endorse any particular brand or company, but can advise on which type of water treatment is likely to work. Homeowners using water treatment units to reduce elevated levels of gross alpha or radium must maintain the unit according to manufacturer's instructions. After installing a water treatment system, a second gross alpha test is recommended to make sure the unit is removing radium effectively.
Where can I get more information?
If you have additional questions or concerns, contact:
Well Water Program
Anne Arundel County Department of Health
Annapolis, Maryland 21401
To get a homeowner's guide, call the Maryland Department of the Environment at 1-800-633-6101 ext. 3714, or click here.
You may also download:
- Map - Testing Area for Gross Alpha and Radium (PDF)
- Well Water Analysis Request for Radium Testing (PDF)
- Application for Assistance - Well Water (PDF)
For more information: