page_title: Pit latrine
section_title: Pour-flush pit latrine
hierarchical_section_title: Pit latrine / Types / Pour-flush pit latrine
caption_attribution_description: English: A SaTo toilet installed in Rwanda. The convex surface of the counter-weighted trap door retains water to ensure an air-tight seal against insects and odors.
context_page_description: A pit latrine, also known as pit toilet, is a type of toilet that collects human feces in a hole in the ground. Urine and feces enter the pit through a drop hole in the floor, which might be connected to a toilet seat or squatting pan for user comfort. Pit latrines can be built to function without water or they can have a water seal. When properly built and maintained, pit latrines can decrease the spread of disease by reducing the amount of human feces in the environment from open defecation. This decreases the transfer of pathogens between feces and food by flies. These pathogens are major causes of infectious diarrhea and intestinal worm infections. Infectious diarrhea resulted in about 700,000 deaths in children under five years old in 2011 and 250 million lost school days. Pit latrines are a low-cost method of separating feces from people.
  A pit latrine generally consists of three major parts: a hole in the ground, a concrete slab or floor with a small hole, and a shelter. The shelter is also called an outhouse. The pit is typically at least three meters deep and one meter across. The hole in the slab should not be larger than 25 centimeters to prevent children falling in.
context_section_description: In a pour-flush pit latrine, a squatting or pedestal toilet with a water seal (U-trap or siphon) is used over one or two offset pits. Therefore, these types of toilets do require water for flushing but otherwise have many of the same characteristics as simple pit latrines. About one to three liters of water is used per flush in that case, and they often have two pits that are used one after the other ("twin pit pour flush pit latrine"). For this reason they are subsumed under the term "pit latrine". The fecal sludge that is removed from the full pits of twin-pit pour-flush pit latrines is somewhat safer to handle and reuse than the fecal sludge from single pit pour-flush latrines. However, significant health risks for the workers who are emptying the pits remain in either case.
  An alternative to U-trap or siphon designs is to incorporate a counter-weighted trap door mechanism that provides an air-tight water seal in the closed position.  Addition of a small amount of water (generally less than 500 ml) overcomes the counterweight and allows the fecal matter to enter the pit. The devices are sold under the name of "SaTo pan" for as little as US$1.85, and more than 800,000 of them have been installed worldwide since introduction in 2013.
caption: A counterweight slab (called SaTo pan) installed in a pit latrine in Rwanda, converting it to a pour flush pit latrine
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