In this study the finished water from three different drinking water treatment plants was examined for rota- and enteroviruses. From this and other recent studies it appears that enteric viruses can occur at detectable levels in finished drinking water meeting current coliform (1/100 ml) and turbidity standards (1. 0 NTU) and containing of free chorine ( greater than 0. 2 mg/l). The isolation of human enteric viruses in these waters is not a condemnation of conventional drinking water treatment, but an indication that water quality parameters currently accepted to ensure the production of microbially-safe water does not necessarily ensure the absence of enteric viruses.