A cesspit is an ambiguous term either used to describe an underground holding tank or a soak pit. An underground pool (also called cesspool) is a tank pit used for the temporary collection and storage of faeces, excreta or faecal sludge. The pit is lined with bricks or concrete, covered with a slab and needs to be emptied frequently. When soil conditions allow, the pit is not constructed watertight (similar to a soak pit) allowing liquid to leach out, while solids decay and collect in the base. A soak pit requires less frequent emptying but leachate infiltration may cause groundwater pollution.