An aerobic system provided to treat sewage generated by a modern larger home which does not have access to a municipal sewage connection The features of this system are adaptable to upgrade and/or replace existing systems. In a preferred embodiment the system uses two 1000 gallon tanks, a first pretreatment tank to receive raw sewage, remove settleable and floatable solids from the sewage, and discharge into a second tank in which the pool of sewage is aerated. The second tank contains a motor driven aerator and a unique self-cleaning filter driven by an outgoing liquid stream from the aerator. After passing through the filter, the liquid is then discharged into a leaching field or nearby stream as permitted by the proper regulatory agency. The self-cleaning rotating filter features a rotating drive energized from the pressurized stream of liquid ejecting from the aerator and impinging upon a side of the filter structure (similarly to a paddle wheel), rotating the filter assembly about its supporting tube as the stream enters spaces between blades of the filter structure, also impinging upon, and passing through a filter cloth, leaving particulate matter on the impinged side of the cloth to be brushed away into the pool of sewage undergoing aeration, during rotation of the filter structure.