The Colilert presence/absence test has been compared with membrane filtration using membrane lauryl sulphate broth for the detection of coliforms and Escherichia coli in a number of different types of water. Colilert appears to give results which are essentially the same as those obtained by membrane filtration whilst taking considerably less time to perform. The data generated in this study are in agreement with a large number of studies published in the United States and suggest that a large comparative study with drinking water samples is warranted.