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.
Chemical toilet
They are frequently seen at outdoor work sites, particularly construction sites, farms, ranches, camp sites and large banks of dozens of portable toilets allow for ready sanitation at large gatherings such as outdoor music festivals. Several portable toilets arranged in these large banks are referred to as a 'sitting' of portable toilets.