Enteroviruses have been shown to occur in substantial numbers in raw water sourcesand treated drinking-water supplies. In view of their prevalence, drinking-water representsa likely, although unconfirmed, source of enterovirus infection. The limited knowledge on the role of waterborne transmission could be related to a number of factors, including the wide range of clinical symptoms, frequent asymptomatic infection,the diversity of serotypes and the dominance of person-to-person spread.Enteroviruses have been detected in drinking-water supplies that met accepted specifications for treatment, disinfection and conventional indicator organisms. Within awater safety plan, control measures to reduce potential risk from enteroviruses should focus on prevention of source water contamination by human waste, followed by adequate treatment and disinfection. The effectiveness of treatment processes used to remove enteroviruses will require validation. Drinking-water supplies should alsobe protected from contamination during distribution. Owing to the higher resistanceof the viruses to disinfection, E. coli (or, alternatively, thermotolerant coliforms) Is not a reliable indicator of the presence/absence of enteroviruses in drinking-water supplies.