The EPA released the interim final Response Protocol Toolbox: Planning for and Responding to Drinking Water Contamination Threats and Incidents (the Response Protocol Toolbox) in winter of 2003 and spring of 2004 to help the water sector effectively and appropriately plan for and respond to contamination threats and incidents. Since its release, EPA has received feedback and suggestions from several sources concerning improvements in the Response Protocol Toolbox. These Response Guidelines have been developed to provide an easy to use document for field and crisis conditions. While the Response Protocol Toolbox provides detailed information, the Response Guidelines are to be viewed as the application of the same principles during an actual incident. As stated in the definition of Response Guidelines in Module 1, Section 4.3 of the Response Protocol Toolbox, Response Guidelines are different from an Emergency Response Plan in that they are essentially a field guide for responding to contamination threats and can be developed in many different formats. This document is intended to be an action oriented document to assist drinking water utilities, laboratories, emergency responders, state drinking water programs, technical assistance providers, and public health and law enforcement officials during the management of an ongoing contamination threat or incident. The Response Guidelines are derived from the content of the six full modules of the Response Protocol Toolbox. The Response Guidelines are not intended to replace the Response Protocol Toolbox and they do not contain the detailed information contained within the six complete modules. Finally, users are encouraged to adapt the Response Guidelines as necessary to meet their own needs and objectives.