Naturally-Occurring Radium In Drinking Water
Facts About Radium(PDF 578 KB)
Having Your Water Tested
Frequently Asked Questions
What is Radium?
Radium is a naturally-occurring, silvery-white, radioactive material that can exist in several forms called isotopes. Radium is formed when uranium and thorium (two other natural radioactive substances) decay (break down) in the environment. Radium is almost everywhere: in soil, water, rocks, plants, and foods at low levels.
Radium only degrades by radioactive decay. Each isotope of radium releases radiation at its own rate. The concentrations of radium-226 and radium-228 in drinking water are generally low, but there are some areas where high concentrations of radium occur due to geologic sources.
In the U.S., radioactivity is usually measured in units called curies. The level of radioactivity in water is usually very low and is measured in picocuries (one picocurie equals one-trillionth of a curie) per liter (pCi/l).
Is Radium in My Water?
Surface water is usually low in radium but groundwater can contain significant amounts of radium due to local geology. Drinking water from wells can contain radium-226 and radium-228 at levels above regulatory standards. High radium levels can be due to the presence of radium in the rock or sands from which the well water is drawn.
Public water supply wells are regularly tested for radium. Radium has been detected in some public and home wells located in the Inner Coastal Plain region of the state. If you own a home well and live in the following counties that are located in the Inner Coastal Plain region, you may want to have your well tested for radium: Aiken, Southern Edgefield, Lexington, Orangeburg, Richland, Calhoun, Kershaw, Sumter, Lee, Darlington, Chesterfield, Florence, Dillon, and Marlboro.
What Levels of Radium are Safe?
Most people are exposed daily (background exposure) to radium levels less than 500 millirems of radiation. The EPA's maximum contaminant level (MCL) for radium (Radium-226 and Radium-228 combined) in public water supplies is 5 picocuries per liter (pCi/l). The MCL has been set well below levels for which health effects have been observed. It is therefore assumed to be protective of public health. EPA estimates the additional lifetime risks associated with drinking water containing 5 pCi/l is about 1 in 10,000. Drinking water at 5 pCi/l for a year is comparable to one chest x-ray or cosmic radiation received during about five flights from Maryland to California. The pie chart below shows the annual dose of an average SC citizen in mrem/yr.
Annual Dose of Average SC Citizen in mrem/yr
Treatment Options
The Department is currently conducting a pilot study to
identify treatment units that will effectively remove the radium in your water
and that you will be able to purchase locally. Culligan of Lexington and
Lowes of Aiken both donated an Ion Exchange (also known as a Water Softener) and
Reverse Osmosis treatment units. Preliminary results of this study suggest
that both technologies can effectively remove radium from drinking water.
Multiple models by other manufacturers are available and may work, but the other
units were not tested. When purchasing a treatment unit, you should look for one that is National
Sanitation Federal (NSF) International approved for removing
radium from drinking water. The web-site for NSF International is www.nsf.org.
If you or a member of your family has high
blood pressure, purchasing an Ion Exchange (Water Softener) unit is not
recommended because sodium is added to the drinking water during the treatment
process.
Ion Exchange (Water Softener)
The ion exchange (IE) or water softener system is actually a combination of processes that treats all of the water going into the home. This system is normally installed by a water treatment professional. The system used in the pilot study was donated by Culligan of Lexington and sells for about $4,000. The ion exchange system is composed of a sediment filter, followed by a mixed be ion exchange filter (95% cation to 5% anion resin), an aeration unit, granular activated carbon (GAC) and ultraviolet light for disinfection. A picture of the system is shown to the right.
The IE (water softener) system was effective in removing
radium. A graph of the preliminary results is presented below. The
yellow triangles on the graph show the concentration of radium remaining in the
water after treatment with the IE (water softener) system.
Reverse Osmosis
The reverse osmosis (RO) system is actually a combination of processes that is usually installed under the kitchen sink for treating the water that is used for drinking, cooking, and making ice. This type of system is called a point-of-use device because it only treats the water at one point in the home. The installation of this device is up to the homeowner. An example of an RO system is shown to the right.
The reverse osmosis system is composed of a sediment filter, followed by a carbon filter, the reverse osmosis filter, and then a final carbon filter. The RO system used in the pilot study was donated by Lowe's of Aiken and sells for about $200.
The RO system was effective in removing radium. A graph showing the preliminary results is shown below. The yellow triangles show the concentration of radium remaining the water after treatment with the RO system.
Contacts
For Health Information
Call
1-888-849-7241 (Toll-Free Community Line)
For general information
contact your local DHEC Office or David Baize at
(803) 898-4300.
Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-4215 . Contact Us