This standard describes the requirements for rapid testing of water samples under emergency situations in laboratories: - taking into account a special context for analyses, e.g. an unknown and unusual contamination; - using or adapting if possible radioactivity measurements methods used in routine to get a result rapidly or applying specific rapid methods previously tested by the laboratory, e.g. for 89Sr determination ; - preparing the laboratory to analyse a large number of potentially contaminated samples. The focus thereby is on cases where rapid radioactivity test methods are applied for all kind of waters. The first steps of the analytical strategy is often based on gross alpha and gross beta as screening methods (adaptation of ISO 10704 and ISO 11704) and gamma spectrometry (adaptation of ISO 10703). Then if necessary, specific radionuclides standards are adapted and applied (for example, Strontium 90 measurement following ISO 13160). This guideline refers to a number of ISO standards. If appropriate, it will also refer to national or other publically available standards. Screening techniques that can be carried out on site are not part of this guide.