S.3 Single Pit Latrine

The Single Pit Latrine is one of the most widely used sanitation technologies. Excreta, along with anal cleansing materials (water or solids) are deposited into the pit. Lining the pit prevents it from collapsing and provides support to the superstructure.The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

The above ground walls and roof built around a toilet or bathing facility to provide privacy and protection to the user.
User interface used for urination and defecation.

As the Single Pit Latrine fills, three processes limit the rate of accumulation: leaching, consolidation and degradation. Urine and water percolate into the soil through the bottom and walls of the pit, while microbial action partially degrades the organic fraction. A smooth, and regularly cleaned platform can promote hygienic conditions by minimising possible human contact with faeces.

Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Design Considerations

Single Pit Latrines vary in size and are typically at least 3 m deep and 1 m in diameter. The top of the pit should be lined to prevent it from collapsing while the bottom of the pit should remain unlined to allow for in filtration. The latrine slab should be at least 10 cm above the surrounding ground to prevent flooding with rainwater runoff. The pit lining should extend at least 40 cm to support the cover, prevent wall collapse and prevent rodents from burrowing into the pit. On average, solids accumulate at a rate of 40–60 L/person/year and up to 90 L/person/year if dry cleansing materials such as leaves or paper are used. The volume of the pit should be designed to contain at least 1,000 L. If 50 people are using one pit of 3 m depth and 1 m diameter and using dry cleansing materials, it will fill after approximately 6 months. The latrine design should include arrangements for emptying. When it is not possible to dig a deep pit or the groundwater level is too high, a Raised Latrine S.7 can be a suitable alternative. It is worth considering upgrading the pit latrine to a more sophisticated technology like a Single Ventilated Improved Pit S.4 , a twin pit system S.5 S.6 or a Double Vault Urine Diversion Dehydration Toilet S.9 at a later stage. This should be considered in the initial design.

The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.A mechanical separation process using a porous medium (e.g., cloth, paper, sand bed, or mixed media bed) that captures particulate material and permits the liquid or gaseous fraction to pass through. The size of the pores of the medium determines what is captured and what passes through.Water that is located beneath the earth’s surface.
User interface used for urination and defecation. The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Materials

The latrine superstructure can be made from local materials, such as bamboo, grass matting, wood, plastic or metal sheeting (though this often heats up the interior). Pit lining materials can include brick, rot-resistant timber, bamboo, concrete, stones, or mortar plastered onto the soil. Some agencies have rapid response kits for slabs and superstructure which can be flown in for immediate use or that can be stockpiled in advance. The slab on top can be fabricated on-site with a mould and cement. In the acute emergency phase, pre-fabricated plastic slabs may be used. However, if produced cheaply, they should be replaced frequently after they become brittle. Other slab materials such as wood or bamboo are also possible, where no other materials are available. Once the pit is full, equipment for emptying or materials for covering the pit are required.

The above ground walls and roof built around a toilet or bathing facility to provide privacy and protection to the user.
User interface used for urination and defecation.

Applicability

Single Pit Latrines can be constructed quickly with local materials during the acute phase of an emergency. Single pits are appropriate for rural and periurban areas. In densely populated areas, pit emptying can be difficult and there is often insufficient space for in filtration. Single pits are especially appropriate when water is scarce and where there is a low groundwater table. They are not suited for rocky or compacted soils, or for areas that flood frequently. For long-term solutions, they should be upgraded to Ventilated Improved Pits S.4 , to lower the presence of flies and odours.

A mechanical separation process using a porous medium (e.g., cloth, paper, sand bed, or mixed media bed) that captures particulate material and permits the liquid or gaseous fraction to pass through. The size of the pores of the medium determines what is captured and what passes through.Water that is located beneath the earth’s surface.

Operation and Maintenance

Daily maintenance associated with a single pit includes regular cleaning, routine operational tasks such as checking availability of water, hygiene items, soap and dry cleansing materials, providing advice on proper use, conducting minor repairs and monitoring of the pit fill level. As pits are often misused for solid waste disposal, which can complicate pit emptying, awareness raising measures X.12 should be a part of installation programmes. When the pit is full it needs either desludging (including subsequent transport, treatment and safe disposal/ reuse options) or if enough space is available the superstructure and squatting plate can be moved to a new pit with the previous pit safely covered and decommissioned X.6.

The process of removing the accumulated sludge from a storage or treatment facility.
Use of recycled water or other sanitation products.
The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

The above ground walls and roof built around a toilet or bathing facility to provide privacy and protection to the user.
User interface used for urination and defecation.

Health and Safety

If used and managed well, Single Pit Latrines can be considered a safe excreta containment technology. They need to be equipped with Handwashing Facilities U.7 and proper handwashing with soap after toilet use needs to be addressed as part of hygiene promotion activities X.12. As with all pit-based systems, groundwater contamination can be an issue and soil properties such as the permeability of the soil and groundwater level should be properly assessed X.3 to limit exposure of water sources to microbial contamination. The Sphere minimum standards on excreta management should be consulted for further guidance. Emptying of the pit C.1 C.2 should be carried out in such a way as to minimise the risk of disease transmission including personal protective equipment and hygiene promotion activities X.12. If the latrine is for communal use additional illumination at night, security guards for protection and accessibility for all users is required.

Consists of urine and faeces that are not mixed with any flushwater. Excreta is relatively small in volume, but concentrated in both nutrients and pathogens. Depending on the characteristics of the faeces and the urine content, it can have a soft or runny consistency.Refers to (semi-solid) excrement that is not mixed with urine or water. Depending on diet, each person produces approximately 50–150 L per year of faecal matter of which about 80 % is water and the remaining solid fraction is mostly composed of organic material. Of the total essential plant nutrients excreted by the human body, faeces contain around 39 % of the phosphorus (P), 26 % of the potassium (K) and 12 % of the nitrogen (N). Faeces also contain the vast majority of the pathogens excreted by the body, as well as energy and carbon rich, fibrous material.The liquid produced by the body to rid itself of nitrogen in the form of urea and other waste products. In this context, the urine product refers to pure urine that is not mixed with faeces or water. Depending on diet, human urine collected from one person during one year (approx. 300 to 550 L) contains 2 to 4 kg of nitrogen. The urine of healthy individuals is sterile when it leaves the body but is often immediately contaminated by coming into contact with faeces.Water that is located beneath the earth’s surface.
Any substance that is used for growth. Nitrogen (N), phosphorus (P) and potassium (K) are the main nutrients contained in agricultural fertilisers. N and P are also primarily responsible for the eutrophication of water bodies.
An organism or other agent that causes disease.User interface used for urination and defecation. The organic molecule (NH2)2CO that is excreted in urine and that contains the nutrient nitrogen. Over time, urea breaks down into carbon dioxide and ammonium, which is readily used by organisms in soil. It can also be used for on-site faecal sludge treatment. See. S.18

Costs

A pit latrine with slab is a low-cost technology, as minimal materials and minimal skills for constructions are needed. Costs will depend on local material prices. The costs of emptying and transporting pit latrine sludge or covering the pit and constructing a new pit also need to be considered. When constructing a new pit, the slab of the previous pit can be reused, if still in usable condition.

Mixture of solids and liquids, containing mostly excreta and water, in combination with sand, grit, metals, trash and/or various chemical compounds. A distinction can be made between faecal sludge and wastewater sludge. Faecal sludge comes from on-site sanitation technologies, i.e. it has not been transported through a sewer. It can be raw or partially digested, a slurry or semisolid, and results from the collection and storage/treatment of excreta or blackwater, with or without greywater. Wastewater sludge (also referred to as sewage sludge) originates from sewer-based wastewater collection and (semi-)centralised treatment processes. The sludge composition will determine the type of treatment that is required and the end-use possibilities.Describes technologies for on-site collection, storage, and sometimes (pre-) treatment of the products generated at the user interface. The treatment provided by these technologies is often a function of storage and is usually passive (i.e. requires no energy input), except a few emerging technologies where additives are needed. Thus, products that are ‘treated’ by these technologies often require subsequent treatment before use and/or disposal. In the technology overview graphic, this functional group is subdivided into the two subgroups: “Collection/Storage” and “(Pre-)Treatment”. This allows a further classification for each of the listed technologies with regard to their function: collection and storage, (pre-) treatment only or both.Refers to the methods through which products are returned to the environment, either as useful resources or reduced-risk materials. Some products can also be cycled back into a system (e.g. by using treated greywater for flushing).A functional group is a grouping of technologies that have similar functions. The compendium proposes five different functional groups from which technologies can be chosen to build a sanitation system:
User interface (U), Collection and Storage/Treatment (S), Conveyance (C), (Semi-) Centralised Treatment (T), Use and/or Disposal (U).
A sanitation system is a multi-step process in which sanitation products such as human excreta and wastewater are managed from the point of generation to the point of use or ultimate disposal. It is a context-specific series of technologies and services for the management of these sanitation products, i.e. for their collection, containment, transport, treatment, transformation, use or disposal. A sanitation system comprises functional groups of technologies that can be selected according to context. By selecting technologies from each applicable functional group, considering the incoming and outgoing products, and the suitability of the technologies in a particular context, a logical, modular sanitation system can be designed. A sanitation system also includes the management and operation and maintenance (O & M) required to ensure that the system functions safely and sustainably. The utilisation of products derived from a sanitation system.
A sanitation system in which excreta and wastewater are collected and stored or treated on the plot where they are generated.
Use of recycled water or other sanitation products.
The means of safely collecting and hygienically disposing of excreta and liquid
wastes for the protection of public health and the preservation of the quality of public water bodies and, more generally, of the environment.

Waste matter that is transported through the sewer.
An open channel or closed pipe used to convey sewage. See C.3 and C.4
Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

Social Considerations

The design of Single Pit Latrines should be discussed with the community beforehand. It should reflect local user preferences ( sitter vs. squatter, anal cleansing practices, direction, positioning, screens etc.) and should account for the accessibility and safety of all users, including men, women, children, elderly and disabled people X.10. The potential handing over to beneficiaries and the roles and responsibilities for O & M need to be agreed upon early on and closely linked to respective hygiene promotion activities X.12 to ensure appropriate use and O & M of the facilities.

A person who prefers to sit on the toilet.A person who prefers to squat over the toilet.
User interface used for urination and defecation.

Fact Sheet Overview

Input Products

Blackwater
Excreta
Faeces

Output Products

Sludge

Emergency Phase

Acute Response + +
Stabilisation + +
Recovery + +

Challenging Ground Conditions

Application Level / Scale

Household + +
Neighbourhood +

Water-based and Dry Technologies

Management Level

Household + +
Shared + +

Technical Complexity

Space Required

Objectives & Key Features

• Excreta containment
• Sludge volume reduction

Strength & Weakness

  • Can be built and repaired with locally available materials
  • Low (but variable) capital costs depending on materials and pit depth
  • Small land area required
  • Flies and odours are normally noticeable
  • Low pathogen reduction with possible contamination of groundwater
  • Costs to empty may be significant compared to capital costs
  • Sludge requires secondary treatment and/or appropriate discharge
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