The results of the US Environmental Protection Agency, Office of Drinking Water, sampling and analysis of volatile organic compounds (VOCs) in finished water supplies that use groundwater sources are discussed. Concentrations of 29 VOCs in addition to five trihalomethanes and total organic carbon from 945 water supplies were measured. The five most frequently found compounds other than trihalomethanes were trichloroethylene, 1,1,1‐trichloroethane, tetrachloroethylene, cis‐ and/or trans‐1,2‐dichloroethylene, and 1,1‐dichloroethane. Approximately half of the samples were taken from a random list of water systems, which were subdivided into two sets of systems—those serving fewer than 10 000 persons and those serving more than 10 000 persons. The nonrandom samples were taken from systems selected by the states, using groundwater sources that were likely to show VOCs in drinking water. Large systems in the random sample had a significantly higher frequency of occurrence of VOC contamination than small systems and were also more likely to have higher levels of contamination.