Current EPA regulations are insufficient to prevent the waterborne transmission of disease, as waterborne outbreaks have occurred in systems which have not exceeded current regulation for coliforms and turbidity. Waterborne outbreaks reported in surface water systems provide data which support the need for pretreatment and filtration of surface waters in addition to disinfection. This treatment is required to ensure the removal and inactivation of waterborne pathogens, especially protozoa such as Giardia and Cryptosporidium. Disinfection of drinking water will likely continue in the United States as the final barrier against waterborne disease. The concerns over the human health effects which may be associated with long-term exposures to chlorine or chlorinated by-products may require changes in disinfection techniques or use of disinfectants other than chlorine. However, additional health research data are required before decisions can be made on changes in current disinfection techniques.