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Radionuclides Rule at a Glance
Maximum Contaminant Level (MCL)
Gross alpha particle activity = 15 pCi/L
Beta particles and photon emitters = 4mrems/yr
Combined radium 226/228 = 5 pCi/L
Uranium = 30 µg/L
Maximum Contaminant Level Goal (MCLG)
Gross alpha particles = Zero
Beta particles and photon emitters = Zero
Combined radium 226/228 = Zero
Uranium = Zero
Health Effects
Increased risk of cancer (all radionuclides), kidney toxicity (uranium)
Sources of Contamination
Most drinking water sources have very low levels of radioactive contaminants ("radionuclides"), most of which are naturally occurring. Sources of man-made radioactive contamination may come from facilities that use, manufacture, or dispose of radioactive substances.
See other contaminants and their MCLs on line.
Most drinking water sources have very low levels of radioactive contaminants ("radionuclides"). Most of these contaminants are naturally occurring in soil and water, although contamination of drinking water sources from human-made nuclear materials, and releases of naturally occurring radionuclides through human activities, can also occur. Most radioactive contaminants are at levels that are low enough that they are not considered a public health concern. At higher levels, long-term (or “chronic”) exposure to radionuclides in drinking water may cause cancer. Chronic exposure to high levels of uranium in drinking water may cause toxic effects to the kidney.
- To protect public health, EPA has established drinking water standards for several radioactive contaminants including combined radium 226/228, beta particles and photon emitters, gross alpha particles, and uranium. All community water systems, regardless of size, must comply with these standards.
This Web site provides information and guidance materials on radionuclides in drinking water to public water systems, state regulators, technical assistance providers, and the general public.
- Basic Information - Learn more about the sources of radionuclides, health effects, and frequently asked questions.
- Radionuclides Rule – Information, including rule development history.
- Compliance Help – Provides available tools and information on complying with the Radionuclides Rule and information on training for water systems, states, engineer consultants/professional engineers, and technical assistance providers.