This paper discusses the use of a genetic algorithm (GA)to optimize the performance of a Japanese water distribution system. Japan is a small county with steep geographical features. Most Japanese cities lie in the plains and water demand is high. Optimization of water distribution is thus very desirable. Optimal distribution system operation will provide a stable water supply to the population and simultaneously reduce operating costs. Computer-aided daily operations can be effectively optimized but calculation time must be fast enough to allow for on-line process control. Therefore, in this paper, a GA is applied to the daily operations strategy decisions for a simple water transmission system to demonstrate it's effectiveness and applicability to larger systems. Reduction of operating costs is also discussed. Includes 4 references, tables, figures.