Cost Efficiency and Scale Economies of Japanese Water Utilities

With the data of 831 Japanese water utilities from 1999 to 2008, we used the stochastic cost frontier analysis with a true fixed-effect model in order to estimate the cost efficiency and scale economies. We found that cost inefficiency was approximately 37%. The economies of water delivery volume were observed and found to be remarkably higher for small water utilities than for large ones. Scale economies were also discovered in small water utilities; however, scale diseconomies are likely to be incurred in larger water utilities. The optimal supply population size of a water utility is estimated to be 85,658 consumers, with a water delivery volume of 15.7 million m3 and a network length of 522 km.