AWWA JAW58477

It is a common practice for utility managers to determine the organic matrix of water by measuring the dissolved organic carbon (DOC) or total organic carbon concentrations and regulating water quality by fixing acceptable thresholds. Although this quantitative approach is generally satisfactory, problems appear during periods of algal proliferation or heavy rainfall, when the water's biodegradable organic fraction may increase dramatically. This study was specifically designed to provide answers about coliform occurrence during these seasonal events. The results confirm the important effect of the origin of dissolved organic matter on the microbiological stability in low-nutritive waters, including drinking water, diluted river water after a heavy rainfall, and diluted algal bloom water. Further, the results indicate that low-nutritive waters with equivalent DOC concentrations conveying organic matter from different origins, and likely to partially pass through the treatment step, allowed the temporary maintenance of the culturability of some coliform bacteria. Includes 36 references, tables, figures.