A system that has an economic advantage over septic tanks under certain soil conditions is the aerobic system. The use of serobic systems is described including unit functions, types of units available, and problems and recommendations for improvement. Aerobic units under experimental conditions were observed to produce a better effluent than a septic tank. However, the performance as claimed by the manufacturers, could be misleading to homeowners. The results of tests run on the units located in the field show that the units are meeting the manufacturers standards about 20% of the time. These units only average about a 44% reduction in BOD. This is assuming an incoming BOD of 250 mg/liter. In some cases the tests showed an influent BOD greater than this.