The selection of bacterial indicators of recreational water quality are considered with respect to suggested ideal characteristics, such as association with pathogens, growth in aquatic environments, resistance to disinfection and ease of enumeration, and through the use of epidemiological-microbiological techniques. On the basis of these considerations the traditional indicators of water quality, total and fecal coliforms, were found to be clearly inadequate. Conversely, E. coli and enterococci met most of the ideal characteristics in freshwater environments, whereas only enterococci were found to be efficient for indexing water quality in marine environments.