ABSTRACT
In 1981, 1982, and 1983, 112 outbreaks and 28,791 cases of illness occurring in potable water systems were reported in the US; 14 outbreaks and 394 cases of illness were caused by consumption of contaminated water from nonpotable sources. Although most outbreaks occurred in community water systems, these data suggest that noncommunity water systems have a greater potential than other water systems for waterborne disease. Analysis indicated no contamination of the well water source, but coliforms were found in the distribution system. An etiologic agent was determined in 60% of the outbreaks. The most frequently identified pathogen in these outbreaks was Giardia lamblia. Water samples for Giardia cysts were collected during 21 of the giardiasis outbreaks, and cysts were recovered from water samples in 18 outbreaks. Either coliform organisms or pathogens were found in the water system demonstrating water contamination in addition to epidemiologic evidence for the waterborne transmission of disease in 59 outbreaks.
