The purpose of this study was to develop and evaluate a simple membrane filter method for concentration and direct enumeration of F- specific coliphages in raw, and finished drinking waters that employs widely available, inexpensive membrane filters and filtration apparatus and yet is able to process sufficiently large sample volumes to detect the low concentrations of phages that might be present in drinking water and their sources. The method developed was then field tested by determining F-specific coliphage concentrations in source waters of drinking water treatment plants and comparing them to those of fecal indicator bacteria. The results of this study provide encouraging evidence that F-specific coliphages can be readily detected in some drinking water sources by a simple, rapid and inexpensive membrane filter method and that these phages may be reliable and useful indicators of fecal contamination and perhaps enteric viruses.