The development of an efficient sanitary sewer system is a more critical design problem than that of a water system. Terrain or natural drainage becomes an extremely important design feature for keeping sewer service costs as low as possible.
The majority of urban development in Butler has occurred in three natural drainage areas of Mound Branch. To serve these areas, the city has developed a gravity flow sanitary sewage system which drains to the wastewater treatment facility, located on Mound Branch, south of the city.
The total interceptor sewer system was designed to serve a population of 9,300; the east relief/south interceptor 5,300 person and the west interceptor 4,000 persons. The sewage treatment plant, which was completed in 1980, was designed to serve a population equivalent of 6,200.