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.
Flush toilet
A toilet need not be connected to a water supply, but may be pour-flushed. This type of flush toilet has no cistern or permanent water supply, but is flushed by pouring in a few litres of water from a container. The flushing can use as little as 2–3 litres. This type of toilet is common in many Asian countries. The toilet can be connected to one or two pits, in which case it is called a "pour flush pit latrine" or a "twin pit pour flush pit latrine". It can also be connected to a septic tank.