Frequent Questions

Why is there a need for a drinking water PAG when the EPA already has regulations for radionuclides in drinking water?

The Safe Drinking Water Act (SDWA) gave the EPA the authority to create Maximum Contaminant Levels (MCLs) for various radionuclides in drinking water. MCLs are based on a lifetime’s continuous exposure and help ensure that, in non-emergent situations, the public’s water is safe to consistently drink over the course 70 years. While the SDWA framework is appropriate for day-to-day normal operations, it does not provide the necessary tools to assist emergency responders with protecting public health directly after an emergency.


An emergency situation, however, is much shorter in scope; the EPA realized that maintaining the MCLs directly following an emergency may not be achievable and, therefore needed to provide guidance that would protect the public’s health during a shorter time period.


The goal of the drinking water PAG is to prioritize potentially scarce water resources for those most at risk in a disaster response. Regardless of the cause of an incident, EPA expects that any drinking water system impacted during a radiation incident will take action to return to compliance with the Safe Drinking Water Act levels as soon as is practical.


For more information on developing emergency drinking water supplies, see the EPA’s guidance on Planning for an Emergency Drinking Water Supply on

For more information about the PAG Manual, visit the PAGs page on

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