AWWA QTC97032

AWWA QTC97032 Comparison of Field and Standardized Techniques for the Enumeration of Total Coliforms and Escherichia Coli in Water
Conference Proceeding by American Water Works Association, 01/01/1997

De Roubin, M.R.; Osswald, M.L.; Bally, D.; Cailas, M.; Joret, J.C.

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The French standard method for the detection of total and fecal coliforms involves membrane filtration (MF) of water through two separate membranes which are incubated on TTC and tergitol lactose agar at 37 degrees C for total coliforms and 44 degrees C for fecal coliforms. A test for tryptophanase, though not required, may be performed to identify E. coli among the fecal coliforms. For surface waters, a microplate test, based on incubation at 44 degrees C and selection of beta-glucuronidase positive strains has been standardized in France and is in the process of standardization at the international level. As well as these standard methods, the Colilert(R) field technique can be used as a presence/absence test, or its results can be quantified by a multiple tube most probable number (MPN) version. Recently, the Quanti-Tray device has been introduced to quantify total coliforms and E. coli in water samples. The objective of this study was to assess the reliability of the Colilert/QuantiTray method for the enumeration of total coliforms and E. coli and to compare the results obtained with those of the membrane filtration and microplate methods.