The Drinking Water Subcommittee of the EPA Science Advisory Board's Environmental Health Committee completed its independent scientific review of the Office of Research and Development Drinking Water Distribution System Research Program. The Subcommittee's major conclusions and recommendations are: the research program needs greater cohesiveness both in terms of scientific integration and research planning; the assimilable organic carbon studies merit additional support to establish whether or not microbiological contaminants are growing within the distribution system; the declining support for research on corrosion is short-sighted; the cost modeling studies should be terminated; and the water quality modeling study should be continued, but with refinement in the research objectives and appropriate verification measures.