The method described is suitable for the determination of faecal coliforms in coastal bathing waters of temperature and tropical seas and is designed to be used in sanitary surveillance of bathing beaches. It is based on the Multiple-Tube Fermentation {MPN) Test and can be employed as an alternative to the Membrane Filtration Culture Method. Whether the Membrane Filtration (MF) Culture Mel hod is preferred to the MPN Test depends on local conditions and personal preferences. In general, the MF method is less labour intensive and due to the preconcentration of the bacteria in the sample it is more suitable in situation where low numbers of coliforms are to be estimated. The MPN test should be given preference when the test sample contains high amounts of particulate matter which will hinder the reading of the MF's atter incubation.