Pit latrine
A pit latrine, also known as pit toilet, is a type of toilet that collects human waste 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 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 recommends that pits be built a reasonable distance from the house, ideally balancing easy access against smell. The distance from water wells and surface water should be at least to decrease the risk of groundwater pollution. 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 involves emptying pits as well as transporting, treating and using the collected fecal sludge. If this is not carried out properly, water pollution and public health 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. 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.
As of 2013 pit latrines are used by an estimated 1.77 billion people, mostly in developing countries. About 419 million people practiced open defecation in 2022, mostly because they have no toilets.
Southern Asia and Sub-Saharan Africa have the lowest access to toilets. The Indian government has been running a campaign called "Swachh Bharat Abhiyan" 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 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 or simply a hole in the ground without a water seal – the common type in most countries in sub-Saharan Africa. Whilst a dry toilet can be with or without urine diversion, 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 toilets". 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 target of increasing access to sanitation 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 are counted as being "improved sanitation" 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.Squatting pan or toilet seat
On top of the drop hole there can either be nothing or there can be a squatting pan, seat 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 although this is rarely the case in practice. In the shelter, anal cleansing materials and a solid waste bin should also be available. A more substantial structure may also be built, commonly known as an outhouse.Locating the pit
Liquids leach from the pit and pass the unsaturated soil zone. Subsequently, these liquids from the pit enter the groundwater where they may lead to groundwater pollution. This is a problem if a nearby water well is used to supply groundwater for drinking water 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 tanks. Detailed guidelines have been developed to estimate safe distances to protect groundwater sources from pollution from on-site sanitation. 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 above groundwater level, and a minimum horizontal distance of between a pit and a water source is normally recommended to limit exposure to microbial contamination. 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 of lateral separation distance might not be sufficient in a strongly karstified system with a downgradient supply well or spring, while of 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 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 in children in rural areas of Romania and Bulgaria in Eastern Europe.