Frequent Questions

What is a drinking water PAG?

The drinking water Protective Action Guide (PAG) recommends a health-based value that can be used in the event of a large-scale radiological emergency to determine when alternative drinking water should be provided and the use of contaminated water supplies be restricted.  This means that, in the same way that the PAGs provide guidance to officials on when to order certain actions like evacuation, the drinking water PAGs provide guidance to officials on when to order certain drinking water-specific actions. These actions could include treating the contaminated water, blending water sources, providing bottled water or water in tanker trucks, or routing water in from a neighboring system.


The drinking water PAGs list doses of radiation that should be avoided during an emergency event. They do not represent acceptable routine exposures. PAGs trigger safety measures to keep doses to the public as low as possible during emergency situations only. The PAGs contain two tiers of guidance that address sensitive populations, such as children and pregnant women, and the general adult population.

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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