A Rapid Method for Detecting Bacteria in Drinking Water

A rapid determination of the total bacterial count in drinking water is important to the operators of treatment plants and distribution systems. It will allow corrective measures in real-time, such as increasing the disinfectant dose or removing water that has high bacterial numbers. The present heterotrophic plate count (HPC) analysis takes seven days and is not useful for operational intervention. The pulpose of this study was to determine if a ,rapid adenosine triphosphate (ATP) assay would estimate the total number of bacteria in minutes. For quality control purposes and also to test the accuracy of both the ATP and HPC test, direct enumeration of the bacteria in a water sample was done using two epifluorescence methods. One was acridine orange direct count (AODC) method, which allows enumeration of both viable and nonviable bacteria. The other was direct viable count (DVC) method, which enumerates viable bacteria. Water samples originated from local, national, and international locations. The sample selection criteria were based on proximity to the laboratory, cooperating water utilities, and the travel of the authors. The results of the study show that the rapid ATP assay is highly correlated with the conventional plate count method and the DVC method, and estimates the bacterial quality of drinking water in minutes.