Under the Safe Drinking Water Act (SDWA), the EPA sets legal limits on the levels of certain radionuclides in drinking water. These limits are applicable to all federal, state and local jurisdictions, including local city public works facilities. Under SDWA, the Agency established a dose-based Maximum Contaminant Level (MCL) for beta particle and photon (gamma) radioactivity of 4 mrem/yr. The MCL is based on lifetime exposure criteria, which assume 70 years of continued exposure to contaminants in drinking water.
For more information about laws and regulations, visit Laws and Regulations on EPA.gov