S.1 Deep Trench Latrine

A Deep Trench Latrine is a widely-used communal latrine option for emergencies. It can be quickly implemented (within 1–2 days) and consists of several cubicles aligned up above a single trench. A trench lining can prevent the latrine from collapsing and provide support to the superstructure.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 trench fills, three processes limit the rate of accumulation whilst providing no significant treatment: leaching, degradation and consolidation. The liquid phase (i.e. urine and water) leaches into the soil through the unlined bottom and walls of the pit, while microbial activity degrades part of the organic fraction and stabilises the pit content. As a result, consolidation occurs.

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.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

Trenches should be around 0.8– 0.9 m wide with at least the top 0.5 m depth of the pit lined for stability. The depth (usually between 1.5 to 3 m) may vary depending on local soil conditions and required speed of implementation. A maximum trench length of 6 m is recommended, providing for six cubicles. End cubicles can be extended to make them accessible for disabled people or provide washing spaces, for example for women during menstruation. Proper drainage should be provided for around the trench to ensure runoff and prevent flooding. When the trench is complete, slabs are placed over it. Prefabricated self-supporting plastic slabs can increase the speed of construction, if available. Alternatively, wooden planks can be secured across the trench (leaving out every third or fourth plank for defecation) until wooden or concrete slabs can be produced locally. The slabs can be fitted with pedestal toilets where users do not squat. Separate trench latrines for men and women should be considered. The trench lifespan (the time required to fill it to within half a metre of the top) is a function of the trench volume, divided by the number of users and estimated excreta volume generated per person. On average, solids accumulate at a rate of 3–5 L/person/month and up to 5–7.5 L/person/month if dry cleansing materials are used. Special attention should be paid to the expected groundwater level and the associated risks of groundwater pollution as well as the topography, ground conditions and soil permeability. Poorly permeable soil will increase the rate at which the pit fills.

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.18Composés d’urine et de fèces non-mélangées à de l’eau de chasse. Leur volume est peu important, mais ils sont concentrés en nutriments et en agents pathogènes. Selon la qualité des fèces, leur consistance peut être molle ou liquide.

Materials

If possible, locally available construction materials should be used. The latrine superstructure can be made from local materials, such as bamboo, wood, plastic or metal sheeting (though this often heats up the interior). The trench lining can be made from bricks, timber, sand bags or temporary lining materials such as bamboo poles or matting. Some relief agencies have rapid response kits for slabs and superstructure which can be used where there are few resources locally.

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

Deep Trench Latrines can be a viable solution in the acute phase of an emergency provided that the technology is acceptable to the users, the ground conditions allow digging of deep trenches and there are sufficient tools, materials and human resources available. As no water is needed for operation it is also a viable solution for water-scarce areas. Deep Trench Latrines can be replicated fast and implemented at scale given that enough space is available.

Operation and Maintenance

Deep Trench Latrines are usually built as communal latrine blocks. The general operation and maintenance (O & M) measures therefore include 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 trench filling level. O & M also includes daily covering of excreta with a 10 cm layer of soil to minimise odour and prevent fly breeding. As trenches are often misused for solid waste disposal, which can complicate later emptying, awareness raising measures X.12 should be a part of installation programmes. Accessibility for desludging vehicles C.2 should be considered. If desludging is not an option the latrines should be decommissioned X.6 when the trench is filled up to 0.5 m below the top of the trench.

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.The process of removing the accumulated sludge from a storage or treatment facility.
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.18Composés d’urine et de fèces non-mélangées à de l’eau de chasse. Leur volume est peu important, mais ils sont concentrés en nutriments et en agents pathogènes. Selon la qualité des fèces, leur consistance peut être molle ou liquide.

Health and Safety

If used and managed well, Deep Trench Latrines can be considered a safe excreta containment technology in the acute response phase. They should 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. Additional illumination at night, security guards for protection and accessibility for all users is required. The trench site should be carefully chosen to avoid areas prone to flooding and drainage ensured as part of construction. 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 identify the minimum distance to the next water source and limit exposure to microbial contamination. The Sphere minimum standards on excreta management should be consulted for further guidance. Emptying the trench 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.

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.18Composés d’urine et de fèces non-mélangées à de l’eau de chasse. Leur volume est peu important, mais ils sont concentrés en nutriments et en agents pathogènes. Selon la qualité des fèces, leur consistance peut être molle ou liquide.

Costs

Building Deep Trench Latrines is relatively inexpensive. Costs vary depending on availability and costs of local materials or use of prefabricated slabs and cubicles. Cost calculations also need to reflect O & M requirements and follow-up costs such as regular desludging, transport, treatment and disposal/ reuse of accumulating sludge.

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 process of removing the accumulated sludge from a storage or treatment facility.
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.
Waste matter that is transported through the sewer.

Social Considerations

If time allows, the design of Deep Trench Latrines should be discussed with the community before installation. 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. As Deep Trench Latrines are usually communal latrines, O & M will require particular attention. Roles and responsibilities for O & M need to be agreed upon early on and closely linked to hygiene promotion activities X.12. As trenches are often misused for solid waste disposal, which might negatively affect later emptying of the trench, special awareness raising measures should be considered.

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. A person who prefers to sit on the toilet.A person who prefers to squat over the toilet.

Fact Sheet Overview

Inputs

Blackwater
Excreta
Faeces

Outputs

Sludge

Response Phase

Acute Response + +
Stabilisation +

Challenging Ground Conditions

Unsuitable

Application Level

Neighbourhood + +

Water-based or Dry Technology

Dry

Management Level

Shared +
Public + +

Technical Complexity

Low

Functional Group

Collection / Storage

Required Space

Medium

Objectives & Key Features

• Excreta containment
• Minimising immediate public health risk
• Fast implementation

Strength & Weakness

  • Inexpensive and quick to construct
  • No water needed for operation
  • Easily understood
  • Unsuitable for areas with high water-table, unstable soil, rocky ground or prone to flooding
  • Often odour and fly problems and issues with other vectors
  • Needs appropriate faecal sludge management concept
  • Groundwater contamination might be an issue
arrow_upward