The methods are intended to indicate the degree of contamination with wastes. Tests for detection and enumeration of indicator organisms, especially coliform group, rather than pathogens, is the principal indicator of suitability of water for various purposes. Presence of coliform indicates fecal contamination of water bodies. Because of this reason, cultural response, biochemical reactions and other characteristics of this group have been studied extensively.
The membrane filter technique, which involves direct plating of the water sample for detection and enumeration of coliforms, is an effective technique as good as the multiple-tube fermentation test for detection of the this group. Direct plating methods such as the membrane filter procedure permit a direct count of coliform colonies. HiMedia offers a wide range of culture media for the enumeration and identification tests for coliforms such as presumptive, confirmatory and completed tests. Also a range of chromogenic dehydrated culture media are available for membrane filter technique and also for the detection of fecal streptococci another indicator of fecal contamination.