Pit Latrines
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A pit latrine, also known as pit toilet, is a type of
toilet A toilet is a piece of sanitary hardware that collects human urine and feces, and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry or non-flush toilets do not. They can be designed for a sitting position popu ...
that collects
human feces Human feces (or faeces in British English) is the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has been further broken down by bacteria in the large intestine. It also contains b ...
in a hole in the ground.
Urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
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 (
dry toilet A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) is a toilet which, unlike a flush toilet, does not use flush water. Dry toilets do not use water to move excreta along or block odors. They do not produce sewage, and ar ...
) or they can have a water seal (pour-flush pit latrine). 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 Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...
. This decreases the transfer of
pathogens In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
between feces and food by
flies Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
. These pathogens are major causes of
infectious diarrhea Gastroenteritis, also known as infectious diarrhea and gastro, is an inflammation of the gastrointestinal tract including the stomach and intestine. Symptoms may include diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydr ...
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 An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry toilet, dry (non-flushing) toilets may be encountered. The term may als ...
. The pit is typically at least deep and across. The hole in the slab should not be larger than to prevent children falling in. Light should be prevented from entering the pit to reduce access by flies. This may require the use of a lid to cover the hole in the floor when not in use. The
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
recommends the pits are built a reasonable distance from the house, balancing issues of easy access versus that of smell. The distance from
water well A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. Th ...
s and
surface water Surface water is water located on top of land forming terrestrial (inland) waterbodies, and may also be referred to as ''blue water'', opposed to the seawater and waterbodies like the ocean. The vast majority of surface water is produced by prec ...
should be at least to decrease the risk of
groundwater pollution Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted ...
. When the pit fills to within of the top, it should be either emptied or a new pit constructed and the shelter moved or re-built at the new location.
Fecal sludge management Fecal sludge management (FSM) (or faecal sludge management in British English) is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal slud ...
involves emptying pits as well as transporting, treating and using the collected fecal sludge. If this is not carried out properly,
water pollution Water pollution (or aquatic pollution) is the contamination of water bodies, usually as a result of human activities, so that it negatively affects its uses. Water bodies include lakes, rivers, oceans, aquifers, reservoirs and groundwater. Water ...
and
public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
risks can occur. A basic pit latrine can be improved in a number of ways. One includes adding a ventilation pipe from the pit to above the structure. This improves airflow and decreases the smell of the toilet. It also can reduce flies when the top of the pipe is covered with mesh (usually made out of
fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...
). In these types of toilets a lid need not be used to cover the hole in the floor. Other possible improvements include a floor constructed so fluid drains into the hole and a reinforcement of the upper part of the pit with bricks, blocks, or cement rings to improve stability. In developing countries the cost of a simple pit toilet is typically between US$25 and $60. Recurring expenditure costs are between US$1.5 and $4 per person per year for a traditional pit latrine, and up to three times higher for a pour flush pit latrine (without the costs of emptying). As of 2013 pit latrines are used by an estimated 1.77 billion people, mostly in
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
. About 892 million people (12 percent of the global population) practiced open defecation in 2016, mostly because they have no toilets. Southern Asia and
Sub-Saharan Africa Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
have the lowest access to toilets. The Indian government has been running a campaign called "
Swachh Bharat Abhiyan Swachh Bharat Mission (SBM), Swachh Bharat Abhiyan, or Clean India Mission is a country-wide campaign initiated by the Government of India in 2014 to eliminate open defecation and improve solid waste management. It is a restructured version of ...
" (Clean India Mission in English) since 2014 in order to eliminate open defecation by convincing people in rural areas to purchase, construct and use toilets, mainly pit latrines. As a result, sanitation coverage in India has increased from just 39% in October 2014 to almost 98% in 2019. It is estimated that 85 million pit latrines have been built due to that campaign as of 2018. Another example from
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
is the "No Toilet, No Bride" campaign which promotes toilet uptake by encouraging women to refuse to marry men who do not own a toilet.


Definitions

Depending on the region, the term "pit latrine" may be used to denote a toilet that has a squatting pan with a water seal or siphon (more accurately termed a pour-flush pit latrine – very common in South East Asia for example) or simply a hole in the ground without a water seal (also called a simple pit latrine) – the common type in most countries in sub-Saharan Africa. Whilst a dry toilet can be with or without
urine diversion Urine diversion, also called urine separation or source separation, refers to the separate collection of human urine and feces at the point of their production, i.e. at the toilet or urinal. Separation of urine from feces allows human waste to ...
, a pit latrine is almost always without urine diversion. The key characteristic of a pit latrine is the use of a pit, which infiltrates liquids into the ground and acts as a device for storage and very limited treatment. Pit latrines are sometimes also referred to as "
dry toilet A dry toilet (or non-flush toilet, no flush toilet or toilet without a flush) is a toilet which, unlike a flush toilet, does not use flush water. Dry toilets do not use water to move excreta along or block odors. They do not produce sewage, and ar ...
s". However, some pit latrines do use water for flushing and are therefore not a "dry toilet". Dry toilets is an overarching term used for several types of toilets, and only refers to the type of user interface, not the storage or treatment part.


Improved or unimproved sanitation

A pit latrine may or may not count towards the
Millennium Development Goals The Millennium Development Goals (MDGs) were eight international development goals for the year 2015 that had been established following the Millennium Summit of the United Nations in 2000, following the adoption of the United Nations Millenniu ...
(MDG) target of increasing access to
sanitation Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...
for the world's population, depending on the type of pit latrine: A pit latrine without a slab is regarded as unimproved sanitation and does not count towards the target. A pit latrine with a slab, a ventilated improved pit latrine and a pour flush pit latrine connected to a pit or
septic tank A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater (sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatme ...
are counted as being "
improved sanitation Improved sanitation (related to but distinct from a " safely managed sanitation service") is a term used to categorize types of sanitation for monitoring purposes. It refers to the management of human feces at the household level. The term was co ...
" facilities as they are more likely to hygienically separate human excreta from human contact.


Design considerations


Size of the drop hole

The user positions themself over the small drop hole during use. The size of the feces drop hole in the floor or slab should not be larger than to prevent children falling in. Light should be prevented from entering the pit to reduce access by flies.


Lids on the drop hole or toilet seat

A lid on the drop hole keeps light out of the pit and helps to stop flies and odors entering the toilet's superstructure. The lid can be made from plastic or wood and is used to cover the hole in the floor when the pit latrine is not in use. In practice, such a lid is not commonly used for squatting type pit latrines but only for sitting type pit latrines with a
toilet seat A toilet seat is a hinged unit consisting of a round or oval open seat, and usually a lid, which is bolted onto the bowl of a toilet used in a sitting position (as opposed to a squat toilet). The seat can be either for a flush toilet or a dry toi ...
.


Squatting pan or toilet seat

On top of the drop hole there can either be nothing (this is the simplest form of a pit latrine) or there can be a squatting pan, seat (pedestal) or bench which can be made of concrete, ceramic, plastic or wood.


Shelter

A shelter, shed, small building or "super-structure" houses the squatting pan or toilet seat and provides privacy and protection from the weather for the user. Ideally, the shelter or small building should have handwashing facilities available inside or on the outside (e.g. supplied with water from a
rainwater harvesting Rainwater harvesting (RWH) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer, or a reservoir w ...
tank on the roof of the shelter) although this is unfortunately rarely the case in practice. In the shelter, anal cleansing materials (e.g. toilet paper) and a solid waste bin should also be available. A more substantial structure may also be built, commonly known as an
outhouse An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry toilet, dry (non-flushing) toilets may be encountered. The term may als ...
.


Locating the pit

Liquids leach from the pit and pass the unsaturated soil zone (which is not completely filled with water). Subsequently, these liquids from the pit enter the groundwater where they may lead to
groundwater pollution Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted ...
. This is a problem if a nearby
water well A well is an excavation or structure created in the ground by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. Th ...
is used to supply groundwater for
drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...
purposes. During the passage in the soil, pathogens can die off or be absorbed significantly, mostly depending on the travel time between the pit and the well. Most, but not all pathogens die within 50 days of travel through the subsurface. The degree of pathogen removal strongly varies with soil type, aquifer type, distance and other environmental factors. For this reason, it is difficult to estimate the safe distance between a pit and a water source – a problem that also applies to
septic tank A septic tank is an underground chamber made of concrete, fiberglass, or plastic through which domestic wastewater (sewage) flows for basic sewage treatment. Settling and anaerobic digestion processes reduce solids and organics, but the treatme ...
s. Detailed guidelines have been developed to estimate safe distances to protect
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
sources from pollution from on-site
sanitation Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...
. However, these are mostly ignored by those building pit latrines. In addition to that, household plots are of a limited size and therefore pit latrines are often built much closer to groundwater wells than what can be regarded as safe. This results in groundwater pollution and household members falling sick when using this groundwater as a source of drinking water. As a very general guideline it is recommended that the bottom of the pit should be at least 2 metres (6') above groundwater level, and a minimum horizontal distance of 30 metres (yards) between a pit and a water source is normally recommended to limit exposure to microbial contamination. /sup>However, no general statement should be made regarding the minimum lateral separation distances required to prevent contamination of a well from a pit latrine. For example, even 50 metres (yards) lateral separation distance might not be sufficient in a strongly
karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
ified system with a downgradient supply well or spring, while 10 metres (yards) lateral separation distance is completely sufficient if there is a well developed clay cover layer and the annular space of the groundwater well is well sealed. If the local hydrogeological conditions (which can vary within a space of a few square kilometres; a square mile or two) are ignored, pit latrines can cause significant public health risks via contaminated groundwater. In addition to the issue of pathogens, there is also the issue of nitrate pollution in groundwater from pit latrines. Elevated nitrate levels in drinking water from private wells is thought to have caused cases of
blue baby syndrome Blue baby syndrome can refer to conditions that cause cyanosis, or blueness of the skin, in babies as a result of low oxygen levels in the blood. This term has traditionally been applied to cyanosis as a result of: #Cyanotic heart disease, whi ...
in children in rural areas of Romania and Bulgaria in Eastern Europe.


Pit lining


Partial

A "partially lined" pit latrine is one where the upper part of the hole in the ground is lined. Pit lining materials can include brick, rot-resistant timber, concrete, stones, or mortar plastered onto the soil. This partial lining is recommended for those pit latrine used by a great number of people — such as a public restroom in rural areas, or in a woodland park or busy lay-by, rest stop or other similarly busy location — or where the soils are unstable in order to increase permanence and allow emptying of the pit without it collapsing easily. The bottom of the pit should remain unlined to allow for the infiltration of liquids out of the pit.


Fully

A fully lined pit latrine has concrete lining also at the base so that no liquids infiltrate into the ground. One could argue that this is no longer a "pit" latrine in the stricter sense. The advantage is that no
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
contamination can occur. The major disadvantage is that a fully lined pit latrine fills up very fast (as the urine cannot escape the pit) which results in high costs to empty and maintain the latrine. Increased odour can also be an issue as the pit content is much wetter and emits more odour. This type of pit latrine is used only in special circumstances, e.g. in denser settlements where groundwater protection is paramount.


Appropriateness

Pit latrines are often built in developing countries even in situations where they are not recommended. These include (adapted fromRieck, C., von Münch, E., Hoffmann, H. (2012)
Technology review of urine-diverting dry toilets (UDDTs) – Overview on design, management, maintenance and costs
. Deutsche Gesellschaft fuer Internationale Zusammenarbeit (GIZ) GmbH, Eschborn, Germany
): * Frequent flooding, resulting in inoperable toilet systems and the contamination of water resources; * Unfavourable soil conditions, such as unstable or rocky soil and high water table, making pit-based sanitation difficult and expensive; * When groundwater is the primary source of drinking water and is likely to be contaminated by pit-based sanitation (for example in denser settlements or with unfavourable hydrogeological conditions); * Limited land space restricts the excavation of new pits if full pit latrines are usually not emptied; * Indoor installations are preferred as they provide greater comfort and security at night thus making them more accessible for all In conditions where pit latrines are not suitable for the above-mentioned reasons, the installations of other types of toilets should be considered, e.g. the
urine-diverting dry toilet A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion that can be used to provide safe, affordable sanitation in a variety of contexts worldwide. The separate collection of feces and urine without any flush water has m ...
(UDDT).


Types

Pit latrines collect
human feces Human feces (or faeces in British English) is the solid or semisolid remains of food that could not be digested or absorbed in the small intestine of humans, but has been further broken down by bacteria in the large intestine. It also contains b ...
in a hole in the ground. The principle of a pit latrine is that all liquids that enter the pitin particular
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
and water used for anal cleansingseep into the ground (the only exception are fully lined pit latrines, see below). File:Pit latrine superstructure, Lesotho (2937020595).jpg, Well maintained pit latrine at a rural household near Maseru,
Lesotho Lesotho ( ), officially the Kingdom of Lesotho, is a country landlocked country, landlocked as an Enclave and exclave, enclave in South Africa. It is situated in the Maloti Mountains and contains the Thabana Ntlenyana, highest mountains in Sou ...
. File:Pit latrine for household, Lesotho (good condition) (2937872226).jpg, Pit latrine from the inside at a household near Maseru, Lesotho (same toilet as shown left from the outside). File:School children in Zimbabwe digging a shallow pit for an Arborloo toilet (a variation of a pit latrine).jpg, School children in
Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and Mozam ...
digging a shallow pit for an
Arborloo An arborloo is a simple type of composting toilet in which feces are collected in a shallow pit and a fruit tree is later planted in the fertile soil of the full pit. Arborloos have: a pit like a pit latrine but less deep; a concrete, ferrocement ...
toilet (a variation of a pit latrine), Epworth in Harare, Zimbabwe. File:Traditional pit latrine in North Kamenya, Kenya.jpg, Traditional pit latrine in North Kamenya,
Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...
. File:Pit latrine with funny user in an amusement part in Germany.jpg, This display shows children what toilets in rural areas in
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
used to look like in the recent past. File:Abandoned pit latrine (2940958117).jpg, Abandoned pit latrine in the peri-urban area of Durban,
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
. File:MLS Kouřim, kadibudka.jpg, Interior of an
outhouse An outhouse is a small structure, separate from a main building, which covers a toilet. This is typically either a pit latrine or a bucket toilet, but other forms of dry toilet, dry (non-flushing) toilets may be encountered. The term may als ...
the structure usually built over the pit to provide privacy.


Ventilated improved pit

The ventilated improved pit latrine (VIP) is a pit latrine with a black pipe (vent pipe) fitted to the pit and a screen (flyscreen) at the top outlet of the pipe. VIP latrines are an improvement to overcome the disadvantages of simple pit latrines, e.g. fly and mosquito nuisance and unpleasant odors. The smell is carried upwards by the chimney effect and flies are prevented from leaving the pit and spreading disease. Despite their simplicity, well-designed single VIPs can be completely smell free, and more pleasant to use than some other water-based technologies. Flies that hatch in the pit are attracted to the light at the top of the ventilation pipe. When they fly towards the light and try to escape, they are trapped by the flyscreen and die. The ventilation also allows odours to escape and minimizes the attraction for flies. The principal mechanism of ventilation in VIP latrines is the action of wind blowing across the top of the vent pipe. The wind creates a strong circulation of air through the superstructure, down through the squat hole, across the pit and up and out of the vent pipe. Unpleasant fecal odors from the pit contents are thus sucked up and exhausted out of vent pipe, leaving the superstructure odor-free. In some cases solar-powered fans are added giving a constant outwards flow from the vent pipe. Flies searching for an egg-laying site are attracted by fecal odors coming from the vent pipe, but they are prevented from entering by the flyscreen at the outlet of the vent pipe. Some flies may enter into the pit via the squat hole and lay their eggs there. When new adult flies emerge, they instinctively fly towards light. However, if the latrine is dark inside, the only light they can see is at the top of the vent pipe. Since the vent pipe is covered by a fly screen at the top, flies will not be able to escape and eventually will die and fall back into the pit. To ensure that there is a flow of air through the latrine, there must be adequate ventilation of the superstructure. This is usually achieved by leaving openings above and below the door, or by constructing a spiral wall without a door. Covering the feces with an absorbent decreases smell and discourages flies. These may include soil, sawdust, ash, or lime, among others. In developing countries, the use of absorbents in pit toilets is not commonly practiced. The vent pipe should have an internal diameter of at least 110 mm (4¼") and reach more than 300 mm (12") above the highest point of the toilet superstructure. Wind passing over the top creates a suction pressure within the vent pipe and induces an air circulation. Air is drawn through the User Interface into the pit, moves up inside the vent pipe and escapes into the atmosphere. Care should be taken that objects, such as trees or houses, do not interfere with the air stream. The vent works best in windy areas, but where there is little wind, its effectiveness can be improved by painting the pipe black. The heat difference between the pit (cool) and the vent (warm) creates an updraft that pulls the air and odours up and out of the pit. To test the efficacy of the ventilation, a lit cigarette can be held over the User Interface; the smoke should be pulled down into the pit and up into the vent and not remain in the superstructure. The mesh size of the fly screen must be large enough to prevent clogging with dust and allow air to circulate freely. Aluminium screens, with a hole-size of 1.2 to 1.5 mm (approx. 1/20"), have proven to be the most effective. Typically, the pit is at least 3 metres (10') deep and 1 to 1.5 metres (3' to 5') in diameter, depending on the number of users. Deep pits can last up to 20 or more years. As liquid leaches from the pit and migrates through the unsaturated soil matrix, pathogenic germs are sorbed to the soil surface. In this way, pathogens can be removed prior to contact with groundwater. The degree of removal varies with soil type, distance travelled, moisture and other environmental factors and, thus, it is difficult to estimate the distance necessary between a pit and a water source. A minimum horizontal distance of 30 metres (100') between a pit and a water source and 2 metres (6') between the bottom of the pit and the groundwater table is normally recommended to limit exposure to microbial contamination.


Twin pit designs

A further improvement is the use of a second pit which is used in alternation with the first pit. It means that the first pit can rest for the duration of time it takes to fill up the second pit. When the second pit is also full, then the first pit is emptied. The
fecal sludge Fecal sludge management (FSM) (or faecal sludge management in British English) is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal slud ...
collected in that first pit has in the meantime undergone some degree of pathogen reduction although this is unlikely to be complete. This is a common design for so-called twin-pit pour flush toilets and increases the safety for those having to enter the pit. Also VIP latrines are sometimes built with two pits, although for VIP toilets one problem can be that the users may not stick to this alternation method and fill up both pits at the same time. The pits are of an adequate size to accommodate a volume of waste generated over one or two years. This allows the contents of the full pit enough time to transform into a partially sanitized,
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
-like material that can be manually excavated. Twin pits are constructed 1 metre (3') apart from each other to minimize cross-contamination between the maturing pit and the one in use. Also pits are constructed over 1 metre (3') from any structural foundation as leachate can negatively impact structural supports. Water within the pit can impact its stability. Therefore, the full depth of the pit walls are lined to prevent collapse and the top 30 cm (12") are fully mortared to prevent direct infiltration and to support the superstructure. There is a risk of
groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...
pollution when pits are located in areas with a high or variable water table, and/or fissures or cracks in the bedrock. As soil and groundwater properties are often unknown, it is difficult to estimate the distance necessary between a pit and a water source. It is normally recommended to have a minimum horizontal distance of 30 metres (yards) between them to limit exposing the water source to microbial contamination. To ensure that only one of the two pits is used at any time, the idle pipe of the junction connecting to the out -of- use pit is closed (e.g. with cement or bricks). Twin Pit Toilets are commonly used in rural
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. the Government's
Swachh bharat Mission Swachh Bharat Mission (SBM), Swachh Bharat Abhiyan, or Clean India Mission is a country-wide campaign initiated by the Government of India in 2014 to eliminate open defecation and improve solid waste management. It is a restructured version of ...
primarily used Twin pit toilets since they were easier and safer to remove and clean. Once removed the waste is used as manure to grow crops


Pour-flush pit latrine

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 (quarts) 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; 1 pint) 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.


Cat hole

A cat hole is a one-time-use pit toilet often utilized by campers,
hiker Hiking is a long, vigorous walk, usually on trails or footpaths in the countryside. Walking for pleasure developed in Europe during the eighteenth century.AMATO, JOSEPH A. "Mind over Foot: Romantic Walking and Rambling." In ''On Foot: A Histor ...
s and other
outdoor recreation Outdoor recreation or outdoor activity refers to recreation done outside, most commonly in natural settings. The activities that encompass outdoor recreation vary depending on the physical environment they are being carried out in. These activitie ...
alists. Also referred to as the "cat method," it is formed by simply digging a hole in the ground just large enough to hold the feces from one defecation event. After use, the hole is refilled with the soil that was dug out.


Maintenance

The requirements for safe pit emptying and
fecal sludge management Fecal sludge management (FSM) (or faecal sludge management in British English) is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal slud ...
are often forgotten by those building pit latrines, as the pit will only fill up in a few years time. However, in many developing countries safe fecal sludge management practices are lacking and causing public health risks as well as environmental pollution.


Pit emptying

When the pit is full, the toilet is no longer usable. The time it takes to fill the pit depends on its volume, the number of users, the soil permeability and groundwater level. It can typically take between one and ten years or even longer in some exceptional cases. At that point, the pit can be covered and abandoned, and a new pit latrine built if space on the property permits this. The new pit latrine may reuse the shelter (superstructure) if the shelter can be moved without collapsing. In peri-urban or urban areas, full pits are not abandoned but rather emptied by
sanitation worker A sanitation worker (or sanitary worker) is a person responsible for cleaning, maintaining, operating, or emptying the equipment or technology at any step of the sanitation chain.World Bank, ILO, WaterAid, and WHO (2019)Health, Safety and Dignity ...
s or the household members themselves so that the toilets can continue to be used at the same location after the emptying has taken place. The emptying can be done manually with shovels and buckets, with manually powered pumps or with motorized pumps mounted on a
vacuum truck A vacuum truck, vacuum tanker, vactor truck, or vactor is a tank truck that has a pump and a tank. The pump is designed to pneumatically suck liquids, sludges, slurries, or the like from a location (often underground) into the tank of the truc ...
which carries a tank for storage. For the fecal sludge to be pumpable, water usually needs to be added to the pit and the content stirred up, which is messy and smelly. Procedures for safe emptying of fecal sludge from pit latrines is a priority for many developing countries where many new pit latrines have been built in rural areas in recent years, such as in Bangladesh. Fecal sludge that has been removed from pits manually or with vacuum tankers is often dumped into the environment indiscriminately, leading to what has been called "institutionalized
open defecation Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...
".


Sludge management

The
fecal sludge Fecal sludge management (FSM) (or faecal sludge management in British English) is the storage, collection, transport, treatment and safe end use or disposal of fecal sludge. Together, the collection, transport, treatment and end use of fecal slud ...
may be transported by road to a
sewage treatment Sewage treatment (or domestic wastewater treatment, municipal wastewater treatment) is a type of wastewater treatment which aims to remove contaminants from sewage to produce an effluent that is suitable for discharge to the surrounding envir ...
facility, or to be composted elsewhere. There are numerous licensed waste hauling companies providing such service in areas where it is needed in developed countries, although in developing countries such services are not well regulated and are often carried out by untrained, unskilled and unprotected informal workers. When managed and treated correctly to achieve a high degree of pathogen kill, fecal sludge from pit latrines could be used as a fertilizer due to its high nitrogen, phosphorus and organic matter content. However, it is hard to ensure that this is done in a safe manner. The number of viable
helminth Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as schi ...
eggs is commonly used as an
indicator organism Indicator organisms are used as a proxy to monitor conditions in a particular environment, ecosystem, area, habitat, or consumer product. Certain bacteria, fungi and helminth eggs are being used for various purposes. Types Indicator bacteria ...
to make a statement about the pathogen load in a fecal sludge sample. Helminth eggs are very persistent to most treatment methods and are therefore a good indicator.


Pit additives

A range of commercial products are available which claim to help reduce the volume of feces in the pit and reduce odor and fly problems. They are collectively described as a
pit additive Pit additives is a commercially-produced material that aims to reduce fecal sludge build-up and control odor in pit latrines, septic tanks and wastewater treatment plants. Manufacturers claim to use effective microorganisms (EM) in their products. ...
and many of them are based on the concept of effective microorganisms. The intention is to add specific strains of microbes to aid the decomposition process – but their effectiveness is disputed and recent research found no effect in scientific test conditions.
Wood ash Wood ash is the powdery residue remaining after the combustion of wood, such as burning wood in a fireplace, bonfire, or an industrial power plant. It is largely composed of calcium compounds along with other non-combustible trace elements presen ...
, leaves, soil,
compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...
, or
sawdust Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sanding, milling, planing, and routing. It is composed of small chippings of wood. These operations can be performed by woodworking machinery, ...
can be sprinkled on top of the feces to decrease the smell in the case of pit latrines without a water seal. This is however not common practice for users in developing countries. Users often do not expect a pit latrine to be odour free, and endure the smell.


Advantages

Advantages of pit latrines may include: * Can be built and repaired with locally available materials * Low (but variable) capital costs depending on materials and pit depth * Small land area required Measures to improve access to
safe water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ag ...
, sanitation and better hygiene, which includes the use of pit latrines instead of
open defecation Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...
, is believed to be able to prevent nearly 90% of deaths due to infectious diarrhea.


Disadvantages

Disadvantages of pit latrines may include: * Flies and odours are normally noticeable to the users * The toilet has to be outdoors with the associated security risks if the person is living in an insecure situation * Low reduction in organic matter content and pathogens * Possible contamination of groundwater with pathogens and nitrate * Costs to empty the pits may be significant compared to capital costs * Pit emptying is often done in a very unsafe manner * Sludge (called fecal sludge) requires further treatment and/or appropriate discharge * Pit latrines are often relocated or re-built after some years (when the pit is full and if the pit is not emptied) and thus need more space than
urine-diverting dry toilet A urine-diverting dry toilet (UDDT) is a type of dry toilet with urine diversion that can be used to provide safe, affordable sanitation in a variety of contexts worldwide. The separate collection of feces and urine without any flush water has m ...
s for example and people are less willing to invest in a high-quality super-structure as it will have to be dismantled at some point.


Costs


Construction

In developing countries the construction cost for a simple pit toilet is between about . This cost figure has a wide range because the costs vary a lot depending on the type of soil, the depth and reinforcement of the pit, the superstructure that the user is willing to pay for, the type of toilet squatting pan or toilet seat chosen, the cost of labour, construction materials (in particular the cost of cement can differ a lot from one country to the next), the ventilation system and so forth. Rather than looking only at the construction cost, the whole of life cost (or life-cycle cost) should be considered, as the regular emptying or re-building of pit latrines may add a significant expense to the households in the longer term. In India, Japan's
LIXIL Group is a Japanese group of companies that manufactures building materials, plumbing fixtures and housing equipment, headquartered in Tokyo. is one of the major Lixil companies. Most of Lixil's plumbing fixtures are sold under the brand. Other L ...
has supplied tens of thousands of twin pit toilet systems that costs $10 or less apiece (in 2018).


Recurrent expenditure

Recurring expenditure costs are between US$1.5 and $4 per person per year for a traditional pit latrine. This includes operational and minor expenditure, capital maintenance expenditure and expenditure on direct support but does not include pit emptying costs. The total recurrent expenditure for more "upmarket" pit latrines has been estimated to be $2.5–8.5 for a VIP-type pit latrine and $3.5–11.5 for a pour-flush pit latrine.


Society and culture


Names

There are numerous colloquial names for pit latrines, such as "long drop", "dunny", "privy".


User experiences

Pit latrines may or may not be an enjoyable experience to use. Problems may occur when the pit latrine is shared by too many people, is not cleaned daily and not emptied when the pit is full. In such cases, flies and odour can be a major nuisance. Also, pit latrines are usually dark places which are difficult to keep clean. Often, handwashing facilities are missing. For these reasons, shared pit latrines can be very uncomfortable to use in developing countries.


Alternative to open defecation

About 892 million people, or 12 percent of the global population, practiced
open defecation Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...
in 2016, mostly because they have no toilets. Southern Asia and
Sub-Saharan Africa Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
have the lowest access to toilets. Pit latrines are a low-cost toilet option that do not require expensive infrastructure. As such, many government agencies and NGOs promote the construction of pit latrines in rural areas (
groundwater pollution Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwanted ...
can be an issue). The
community-led total sanitation Community-led total sanitation (CLTS) is an approach used mainly in developing countries to improve sanitation and hygiene practices in a community. The approach tries to achieve behavior change in mainly rural people by a process of "triggering ...
approach results in the spontaneous construction and sustained use of pit latrines rather than
open defecation Open defecation is the human practice of defecating outdoors ("in the open") rather than into a toilet. People may choose fields, bushes, forests, ditches, streets, canals, or other open spaces for defecation. They do so either because they do ...
.


India example

The Indian government has been running the
Swachh Bharat Abhiyan Swachh Bharat Mission (SBM), Swachh Bharat Abhiyan, or Clean India Mission is a country-wide campaign initiated by the Government of India in 2014 to eliminate open defecation and improve solid waste management. It is a restructured version of ...
(Clean India Mission) since 2014 in order to eliminate open defecation and to convince people in rural areas to purchase, construct and use toilets, mainly pit latrines. This campaign is a combination of building new toilets and encouraging behavior change. It is estimated that 50 million additional pit latrines have been built due to that campaign between 2014 and 2017. Another example is the campaign that took place in
Haryana Haryana (; ) is an Indian state located in the northern part of the country. It was carved out of the former state of East Punjab on 1 Nov 1966 on a linguistic basis. It is ranked 21st in terms of area, with less than 1.4% () of India's land ar ...
with slogans such as "No Toilet, No Bride" or "No loo, no "I do"". This campaign promotes the construction of toilets (usually pour flush pit latrine toilets). In rural India, there are sometimes cultural preferences for open defecation and these may be difficult to overcome with unattractive toilet designs, such as pit latrines.


See also

*
Bucket toilet A bucket toilet is a basic form of a dry toilet whereby a bucket (pail) is used to collect excreta. Usually, feces and urine are collected together in the same bucket, leading to odor issues. The bucket may be situated inside a dwelling, or in ...
*
Cesspit A cesspit (or cesspool or soak pit in some contexts) is a term with various meanings: it is used to describe either an underground holding tank (sealed at the bottom) or a soak pit (not sealed at the bottom). It can be used for the temporary co ...


References


External links


Single pit latrine on eCompendium website
the online version of the Eawag-Sandec Compendium

(WEDC, Loughborough University, UK) * Photos of pit latrines: Search for "pit latrine" in th
Sustainable Sanitation Alliance photo database on flickr

Storage and Treatments On-site storage and treatment technologies
in Sustainable Sanitation and Water Management (SSWM) toolbox {{authority control Wikipedia medicine articles ready to translate Sanitation Toilets Toilet types