Radionuclides in Drinking Water

Learn Community water systems (CWSs) that use source water containing radium-226 (Ra-226), radium-228 (Ra-228), gross alpha particle activity, beta particle and photon radioactivity, or uranium must comply with the Radionuclides Rule (see This content provides general information to CWSs on: the available treatment technologies for the removal of radium, uranium, and gross alpha particle activity; the residuals produced by each technology; disposal options; and, the regulations governing these options. The applicable regulatory requirements are described here in summary form only and there may be additional federal or State laws or regulations that apply to you beyond those described in this material content. You need to consult the statutory and regulatory provisions that apply to the waste you generate or manage in order to determine the requirements with which you must comply. This document also provides additional recommendations and information on possible options; these are not regulatory requirements and are provided for your information only. This document does not cover residuals from treatment of beta particle or photon radioactivity. Information on those radionuclides can be obtained from your primacy agency. EPA will continue to review and update this guidance as necessary and appropriate.

Compliance Options: Treatment Technology Descriptions

In accordance with the Radionuclides Rule, all community water systems must comply with the following maximum contaminant levels (MCLs) at each entry point to the distribution system (EPTDS):

  • gross alpha particle activity (15 pCi/L),
  • combined radium 226/228 (5 pCi/L),
  • beta particles and photon emitters (4 mrem/yr), and
  • uranium (30 µg/L).

Systems utilizing multiple sources will need to consider a mitigation strategy for each EPTDS that exceeds the revised MCL.

A system will need to optimize existing treatment or install new treatment if it has high levels of radionuclides in source waters and cannot achieve compliance through non-treatment options such as blending or development of an alternative source. The system should first determine whether its existing treatment technology is capable of removing radionuclides even though it may not be doing so currently.

Treatment may be accomplished at the wellhead or as a centralized treatment system (water pumped from several sources to a centralized location for treatment before entering the distribution system). Also, treatment located at the point-of-use (POU) or point-of-entry (POE) within a building or entering a building, respectively, may be appropriate in some situations.

Click on a link below to find information on each compliance option. These descriptions provide a first-look introduction to radionuclide treatment technologies. Additional information can be found at: