A septic tank is a watertight container, usually underground, that separates solid materials from wastewater. Depending on the size of the house, the tank can hold from 500 to 2,000 gallons of substance. The materials in the tank are divided into three parts: solid waste like scum or grease, liquid waste and sludge. Without regular inspections, a tank’s pipes, walls and sealants can degrade over time without notice, resulting in leakage of contaminated water and untreated sewage by Annie Yi-Chieh Liao