Although considerable data have been published on the occurrence and distribution of pesticides in surface water, there is little information from full-scale studies on how pesticides in source water are affected by the treatment process. In this pilot study, source water and finished (treated) water samples were collected from 12 community water systems (CWSs) across the United States and analyzed for water-soluble pesticides. The facilities were selected in part because they relied on surface water as their source water and their supplies were considered vulnerable to pesticide contamination. A treatment plant's, ability to remove or degrade a pesticide has been shown to be dependent on numerous variables, including surface water characteristics, pH, oxidant type, contact time, and operational procedures. Among the 12 CWSs tracked by this research, the treatment processes effectiveness varied significantly. Although some pesticides in the source water were removed by treatment, others passed through the treatment process and into the distribution system. Future study is needed to examine exactly how the treatment process within each of the participating systems affected pesticide concentration. None of the pesticides, analyzed in this research were found at concentrations above standards set by the US Environmental Protection Agency for treated water. However, this work should serve as a wake-up call for treatment personnel and facility managers: If their source water is contaminated with pesticides, then the treatment process may not be completely effective at removing these pesticides from the water. - MPM.