The size and type of tank required are the two most frequent factors to take into account before establishing a new septic system. In the United States, private sewage disposal is becoming more popular; 33 percent of newly built residences choose onsite wastewater treatment. Septic tank systems combined with a soil absorption system or a drain field, are the least expensive method available for treating residential wastewater. The size of the septic tank you will require largely relies on the size of the house and the number of occupants. This article explores some of the factors that determine septic tank sizes.