Characterization of CSO Microbial Contamination and their Risks to Drinking Water Sources

Combined sewer overflows (CSOs) have been recognized as one of the major causes of surface water quality impairment, particularly drinking water supplies. Occurrence of CSOs as a discharge of an untreated mixture of wastewater effluents and stormwater into waterbodies upstream of drinking water sources may potentially deliver high amounts of fecal loads to downstream intakes, causing periods of elevated concentrations. The CSO-induced peak periods at the intakes must be characterized with regards to the level of microorganisms during these periods while treatment processes in drinking water treatment plants must effectively reduce concentrations by the required amounts.