The purpose of the study is an attempt to find out what happens in the residential sewage disposal system and its parts under various loading and environmental circumstances. With such information it should be possible to develop recommendations for design standards and servicing procedures which are fundamentally sound because they are based on facts. A staggering variety of experiments and investigations have been conducted by the Staff at Cincinnati. Efforts have been expended along three major lines of endeavor: Field Investigations, Soil Studies, and Studies of Septic Tanks and Related Appurtenances.