A pit latrine is one of the simplest forms of sanitation: a hole dug in the ground, covered by a floor or platform with a drop hole, where human waste is deposited and slowly decomposes below the surface. It is the most widely used sanitation technology in low-income countries and remains the primary alternative to open defecation for billions of people. Despite its simplicity, the design details of a pit latrine, from the depth of the hole to the quality of the covering slab, make a significant difference in whether it actually protects health.
How a Pit Latrine Works
The basic concept is straightforward. A pit, typically 2 meters or deeper, is excavated into the ground. A floor slab (made of concrete, wood, or compacted earth) is placed over the pit, with a small hole for the user to squat or sit over. A simple superstructure of walls, a roof, and a door provides privacy. Waste falls into the pit, where bacteria break it down over time. Liquids slowly seep into the surrounding soil, while solids accumulate and gradually reduce in volume through decomposition.
Because the waste is contained underground and physically separated from people, a well-built pit latrine interrupts the main route diseases travel from one person to another: the fecal-oral pathway. That pathway includes direct contact with feces on hands or feet, contamination of food and water, and transmission by flies that land on exposed waste and then on food.
What Makes a Pit Latrine “Improved”
Not all pit latrines offer the same level of protection. The WHO/UNICEF Joint Monitoring Programme, which tracks global sanitation, draws a clear line between improved and unimproved facilities. A pit latrine with a slab counts as improved sanitation. So does a ventilated improved pit latrine (VIP), which adds a vent pipe with a fly screen to reduce odors and keep insects out. A pit latrine without a slab, or an open pit, is classified as unimproved, placing it just one step above open defecation. Shared latrines, even well-built ones, are also not considered improved under these standards.
Research from rural Ethiopia illustrates why these distinctions matter. Children under five living in households with well-constructed latrines (featuring a pit at least 2 meters deep, a slab, a drop-hole cover, walls, a roof, a door, and handwashing facilities) had 54% lower odds of diarrhea compared to children using latrines missing one or more of those features. The likely reason: well-constructed latrines had consistently less feces and fewer flies visible around the drop hole. Each component contributes something. The slab prevents foot contact with waste and keeps the area cleanable. The cover over the drop hole blocks flies. The walls and door encourage regular use. Handwashing facilities catch pathogens before they reach mouths.
Ventilated Improved Pit Latrines
A VIP latrine is an upgraded version that adds a vertical vent pipe, usually 110mm in diameter, attached to the outside of the structure. The pipe is topped with a fly screen. Wind passing over the top of the pipe creates airflow that pulls odors up and out of the pit, rather than through the drop hole into the user’s face. Flies attracted to the smell enter the vent pipe but are trapped by the screen. The interior of the superstructure is kept deliberately dark, so any flies inside the pit are drawn toward the light at the top of the vent pipe rather than up through the drop hole. This design significantly reduces both the smell and the insect problem that discourage people from using basic pit latrines.
Protecting Groundwater
The biggest environmental risk of pit latrines is contamination of nearby water sources. As liquid waste seeps through the soil surrounding the pit, pathogens and chemical pollutants like nitrates can travel into groundwater. How far they travel depends on soil type, the depth of the water table, and how long the pit has been in use.
Recommended safe distances between pit latrines and water sources vary, but common guidelines converge on a few key numbers. The WHO suggests minimal risk of groundwater pollution where at least 2 meters of relatively fine soil separates the bottom of the pit from the water table. Laterally, 15 meters is a widely cited minimum distance between a pit latrine and a water source, though this can be reduced if the well is not directly downhill from the pit. In practice, many countries and organizations set more conservative standards. Haiti requires at least 30 meters from any drinking water source. South Africa’s guidelines call for 75 meters. The Sphere Project, which sets standards for humanitarian disaster response, recommends 30 meters as a minimum.
Soil type matters enormously. Sandy or gravelly soil lets contaminants travel farther and faster. Clay-rich or fine-grained soil filters pathogens more effectively. In areas with fractured rock, contamination can travel unpredictable distances through cracks, making safe siting especially difficult. One review noted that as pits age, the recommended safe distance increases: 20 meters for pits used less than a decade, 36 meters for one to two decades, and 48 meters for pits in use longer than that, because the soil’s natural filtering capacity becomes saturated over time.
When the Pit Fills Up
A pit latrine is not permanent. Depending on the size of the pit and the number of users, it will eventually fill. Systems designed for shared use in urban areas are often sized for emptying roughly every two years, assuming about 40 liters of sludge accumulation per person per year. Single-household latrines in rural areas with larger pits can last much longer.
When the pit is full, there are two options: empty it or abandon it and dig a new one. In rural areas with available land, the traditional approach is to cover the full pit with soil and relocate the superstructure over a new pit. This is considered a safe management method when space allows. The buried waste continues to decompose and, over time, becomes relatively harmless. Some communities even plant fruit trees over old pits to take advantage of the nutrient-rich soil.
In densifying urban and peri-urban areas, covering and abandoning pits becomes unworkable because there is simply no room for new ones. Emptying is the only option, and how it is done has major health implications. Unhygienic emptying, using buckets and shovels with no protective equipment, exposes workers directly to raw waste and often results in sludge being dumped nearby rather than transported to a treatment facility. Hygienic emptying uses mechanized equipment like vacuum tankers or manual pumps (such as a device called a Gulper) along with protective gear including gloves, masks, and boots. Mechanized emptying is far more likely to result in waste being transported to a treatment plant. In one study in Maputo, Mozambique, nearly half of households using mechanized emptying reported waste was taken to a treatment facility, compared to zero among those using manual emptying.
Why Pit Latrines Still Matter
Pit latrines are sometimes dismissed as primitive, but they remain the most realistic sanitation option for hundreds of millions of people in areas without sewage infrastructure or reliable water supply. They require no water to operate, no electricity, and relatively little technical expertise to build. The materials for a basic version are locally available almost anywhere. For communities transitioning away from open defecation, a well-built pit latrine represents a dramatic improvement in disease prevention, particularly for young children who are most vulnerable to diarrheal diseases.
The critical factor is not whether a pit latrine is used, but whether it is built and maintained properly. A deep pit, a solid slab, a cover for the drop hole, a structure that provides privacy and keeps out rain, and handwashing supplies nearby: these features collectively determine whether a pit latrine functions as a genuine barrier against disease or merely concentrates waste in one spot without meaningfully reducing exposure.