DURING the past year, the East Bay Municipal Utility District undertook the compilation of the costs of pipe laying in its system. Such a study is, of course, influenced by a number of variable factors which tend to make comparisons difficult; so, to arrive at some valid basis of comparison, the investigation was projected to deal exclusively with cast-iron pipe laid in streets paved with oiled macadam, and to consider only the three most common sizes (4-, 6and 8-inch) of pipe found in distribution systems. Information on the study, together with a description of the details of the cost system employed, are presented here. The District employs eight crews of men to install new pipe line extensions and to renew old lines. Each crew is under the direction of a foreman and is a complete unit within itself. These crews are equipped with portable air compressors mounted on pneumatic tires, tool wagons, dump truck and covered service truck designed to carry small tools and other necessary material, as well as the personnel which varies in number from ten to twenty men, depending on the size of pipe and length of line to be installed. Daily time sheets (Fig. 1) for all labor are made out in triplicate by the foreman. Included in the reports are records of the type of work in which each man was engaged, the number of hours worked, the type of equipment used and the number of hours for which each type of equipment was used. Each day these reports are turned in to the superintendent's office, where the data are checked and the extra copies routed, one to the auditing department and the other to the timekeeping division.