DIN EN ISO 9308-1:2012-12

This standard describes a method for the detection and enumeration of E. coli and coliform bacteria in water for human consumption. The method is based on membrane filtration, subsequent culture on a differential agar medium and calculation of the number of target organisms in the sample. Due to the low selectivity of the differential agar medium, background growth can interfere with the reliable enumeration of coliform bacteria and E. coli, for example in surface waters or shallow well waters. This method is not suitable for these types of water. This part of ISO 9308 is especially suitable for drinking water, disinfected pool water and other waters with low bacterial numbers. Strains of Escherichia coli which are ß-glucuronidase negative, such as Escherichia coli O157, will not be detected, according to this standard.