ABSTRACT
The besides being hindered by delays in initiating an investigation, engineering studies are further hampered because clues and information developed by the epidemiologist through interviews with cases and controls do not become available in usable form for 3 to 5 days. An engineering evaluation of the water system including source, treatment, and distribution is required to identify sources of contamination, defects in facilities, and failures in operation that may have contributed to the causes of the outbreak. The distribution network is the most difficult component of the water system to evaluate since nearly all of it is underground. The unit process having the greatest impact on reducing microbial challenge and preventing waterborne disease transmission is disinfection. The epidemiological information should be used to identify a critical period of time when consumers were likely exposed to the contaminant, and treatment information for that period should be detailed and specific.
