This book focuses on the analysis of water samples that may have been contaminated as a result of a radiological or nuclear event, such as a radiological dispersion device (RDD), improvised nuclear device (IND), or an intentional release of radioactive materials into a drinking water supply. In the event of a major incident that releases radioactive materials to the environment, the EPA will turn to selected radioanalytical laboratories to support its response and recovery activities. During all phases of an incident response, radioanalytical resources are needed for identifying the radionuclide source terms, quantification of the radionuclides in a variety of media, and the gross radiation screening of samples for prioritisation of sample processing or for information related to the general level of contamination.