Most water systems are required to monitor for radioactivity and certain radionuclides, and to meet Maximum Contaminant Levels (MCLs) for these contaminants, to comply with the Safe Drinking Water Act (SDWA). Currently, EPA requires drinking water to meet MCLs for beta/photon emitters (includes gamma radiation), alpha particles, combined radium 226/228, and uranium. However, this monitoring is required only at entry points into the system. In addition, after the initial sampling requirements, only one sample is required every 3 to 9 years, depending on the contaminant type and the initial concentrations.
