The Detection and Disinfection of Pathogens in Storm-Generated Flows

A recreational water9s disease-producing potential is usually assessed by bacterial indicators of human fecal contamination, however many of these indicator bacteria also originate from soils, vegetation, and animal feces. Stormwater runoff can contain high densities of the nonhuman indicator bacteria and epidemiological studies of recreational waters receiving stormwater runoff have found little correlation between indicator densities and swimming related illnesses. In addition a number of non-enteric pathogens found in stormwater runoff have been linked to respiratory illnesses and skin infections, a risk which is not assessed by the present fecal indicators. Therefore, for receiving waters with predominantly stormwater discharges, the current bacterial indicators are not suited to accurately assess the water9s total illness producing capacity. The intermittent and irregular nature of stormwater discharges causes unique disinfection requirements which are discussed in connection with present practices and developments. The need for epidemiological studies to assess the risk from nonhuman and non-enteric pathogens is recommended.