In August 1953, the Joint Committee on Chlorine Supply submitted its initial report dealing with the supply, inventories, and use of chlorine in water and sewage treatment plants. In May 1958, the committee planned a follow‐up survey of representative water and sewage treatment plants in the continental United States. A total of 191 cities were selected, which represented the range of urban population sizes in each of five geographic sections of the country. Approximately the same number of cities in each population range were selected for each section. From each city, water and sewage treatment plants serving the same communities were chosen. Of the total number selected data were received from 151 water plants and 51 sewage treatment plants; these data have been used to develop the compilations and analyses of this report. The small number of returns from the sewage treatment plants is attributed to the relatively small percentage of sewage plants using chlorine.