Septic tank
A septic tank is an underground chamber made of concrete, fiberglass or plastic through which domestic wastewater (sewage) flows for basic treatment. Settling and anaerobic processes reduce solids and organics, but the treatment efficiency is only moderate (referred to as "primary treatment"). Septic tank systems are a type of simple onsite sewage facility (OSSF). They can be used in areas that are not connected to a sewerage system, such as rural areas. The treated liquid effluent is commonly disposed in a septic drain field which provides further treatment. However, groundwater pollution may occur and can be a problem.
Health in Egypt
Soakaway latrines, which are common in rural areas, often do not work properly due to the high groundwater table, infrequent emptying and cracks in the walls. Thus sewage leaks out and contaminates the surrounding streets, canals, and groundwater. Trucks that empty latrines and septic tanks do not necessarily discharge septage into wastewater treatment plants, but rather dump the content in the environment.