PROSPECTS FOR NEW TECHNIQUES FOR RAPID BACTERIOLOGICAL MONITORING OF DRINKING-WATER

The microbiological safety of water supplies is at present assured by monitoring for the absence of the faecal indicator organisms, total co liform bacteria and Escherichia coli. This monitoring work represents the bulk of the workload of microbiology laboratories in the water ind ustry. The accuracy of current methods is not questioned, but the time s taken to obtain a presumptive result (18 h) and a confirmed result ( up to 72 h) impose delays, particularly with regard to the recommissio ning of distribution systems. There is therefore a continued demand fo r more rapid techniques, which has not been satisfied, despite the adv ances in analytical methods which have been adopted in other industrie s. Alternatives to the traditional culture-based methods are reviewed in this paper, and promising techniques for water applications are hig hlighted. Highly specific bacterial labelling methods and sensitive in strumentation for detection and enumeration already exist, so that rap id same-day detection of coliforms is technically feasible. Suitable s eparation methods for rapid analysis of water samples have not yet bee n developed, but antibody-mediated separations which are now employed in clinical and food microbiology may be applicable.