This Study includes the information of integrated discussion and economies of scale on local governments' sewerage treatment plant through translog function based on the reality reports of sewerage treatment plant operation published by Ministry of Environment and sewerage statistics data from 2005 to 2010. Based on analysis results from the data of 35 local governments in Jeollanamdo and Jeollabukdo, which are selected as pilot project areas of sewerage facility integration by Ministry of Environment and have low percent of sewered population, it shows the existence of economies of scale. The economies of scale on sewerage treatment show the loss of approximately 22,211 thousand ton/day in sewage treatment, it is 1.7 times compared to the average treatment amount of 35 local governments as of 2010. It means the economies of scale can be achieved by lowering operation cost along with large scale integration in installation, operation and maintenance due to the features of sewerage industry as one of network industry.