Disinfection of drinking water has been used for many years for the prevention of waterborne disease through inactivation of pathogenic microrganisms. In general, disinfection practices in the field have developed through experience rather than application of specific disinfection data derived from controlled experiments. Concerns about waterborne disease outbreaks caused by the protozoan Giardia lamblia, the cysts of which are very resistant to inactivation, and the need to more precisely control the disinfection process to reduce formation of potentially hazardous chemical byproducts have made it necessary to more closely examine the biocidal aspects of drinking water disinfection. The use of mathematical concepts based on microbial inactivation kinetics to predict disinfectant concentration and contact times needed to inactivate specific proportions of various pathogens and indicator species has received increasing attention as an approach to better control of the disinfection process.

"July 1986." Distributed to depository libraries in microfiche. PB86-232568 "EPA/600/2-86/067"