Japan's sewerage system

This paper traces the history of sewer construction in Japan. The first sewers were built for flood control, and as late as the end of the Second World War there were only six cities enjoying sewer systems with treatment facilities. Rapid industrialization increased pollution problems and led to accelerated sewer development. Advances in the technology of sewage treatment are outlined. Today 30% of Japan's population is served by sewer systems, and identifying cost‐effective means of increasing that proportion is a major priority. The Experimental Sewer System, developed in Tokyo, is described. Finally, a new method for the estimation of peak flow in sewer pipes, entitled grid analysis, is presented.