S.4 Single Ventilated Improved Pit (VIP)

The Single VIP is seen as an improvement over the Single Pit Latrine (S.3) because continuous airflow through the ventilation pipe prevents odours and acts as a trap for flies as they escape towards the light.

When correctly designed, built, used and maintained, Single VIPs can be completely odour-free. 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 fly-screen and eventually die. The ventilation also allows odours to escape and minimises the attraction for flies.

Design Considerations

The only design difference to a Single Pit Latrine is the ventilation. All other design considerations are covered in the Simple Pit Latrine sheet S.3 . For the ventilation, a straight vent pipe is needed with an internal diameter of at least 11 cm and reaching more than 30 cm above the highest point of the toilet superstructure. Wind passing over the top creates a suction pressure within the pipe and induces an air circulation. Air is drawn through the user interface into the pit and moves up the vent pipe. The vent works best in windy areas and surrounding objects, such as trees or houses, should not interfere with the air stream. Where there is little wind, effectiveness can be improved by painting the pipe black. The heat difference between pit (cool) and vent (warm) creates an additional updraft. To test ventilation efficacy, a smoking stick or similar object can be held over the user interface; the smoke should then be pulled down into the pit. The mesh size of the fly screen must be large enough to prevent clogging with dust and allow air to circulate. The toilet interior must be kept dark (or the toilet hole kept closed with a lid) so that flies in the pit are attracted to the light of the vent pipe. VIPs without dark interiors, or with uncovered defecation holes, reduce odour but not flies.

Describes the type of toilet, pedestal, pan, or urinal that the user comes into contact with; it is the way users access the sanitation system. In many cases, the choice of user interface will depend on the availability of water and user preferences. Additionally, handwashing facilities have been included here with a dedicated technology information sheet as a constant reminder that each sanitation user interface needs to be equipped with handwashing facilities for optimal hygiene outcomes.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 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. Used water from any combination of domestic, industrial, commercial or agricultural activities, surface runoff/stormwater, and any sewer inflow/infiltration.

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. 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 ventilation pipe can be made from a range of materials, including PVC or metal piping, masonry, hollowed bamboo or similar.

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 VIPs are a significant improvement over Single Pit Latrines and can be considered a viable solution in all phases of an emergency. Special attention should be paid to the anticipated groundwater level and associated risks of groundwater pollution. As no water is needed for operation it is also an appropriate solution for water scarce areas. It can be replicated quickly and implemented at scale given sufficient space. The Single VIP should be built in an area with a good breeze to ensure effective ventilation. Like other pit latrines they are not suitable in areas with rocky or compacted soils or in areas that flood frequently. VIPs rarely work as communal toilets as they are often improperly used and with unclear ownership, maintenance quickly becomes a problem.

Water that is located beneath the earth’s surface.
User interface used for urination and defecation.

Operation and Maintenance

General operation and maintenance (O & M) tasks include regular cleaning, ensuring the availability of water, hygiene items, soap and dry cleansing materials, conducting minor repairs and monitoring pit fill levels. Dead flies, dust and other debris should be removed from the fly screen to ensure good air flow. 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. VIPs for general public use may have a sludge build-up rate too fast for absorption into the soil and will thus require regular emptying. If regular desludging is needed the accessibility for desludging vehicles C.1 C.2 must be considered.

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.
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.

Health and Safety

If used and managed well, a Single VIP can provide a clean, comfortable, and acceptable toilet. Single VIPs need to be equipped with Handwashing Facilities U.7 . 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. Pits remain susceptible to failure and/or overflowing during floods and health risks associated with flies are not completely removed by ventilation.

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 a Single VIP can be relatively inexpensive. Costs vary depending on the availability and costs of local materials or use of prefabricated slabs and cubicles. However, cost considerations also need to reflect additional O & M requirements and potential follow-up costs like regular desludging, transport, treatment and sludge disposal/ reuse.

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

The design of the Single VIP 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 accessibility and safety of all users including men, women, children, elderly and disabled people (X.10). Potential handing over to beneficiaries and roles and responsibilities for O&M need to be agreed upon early on and closely linked to hygiene promotion (X.12) in order to ensure appropriate use 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. 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 + +
Recovery + +

Challenging Ground Conditions

Unsuitable

Application Level

Household + +
Neighbourhood + +

Water-based or Dry Technology

Water-Based & Dry

Management Level

Household + +
Shared + +

Technical Complexity

Low

Functional Group

Collection / Storage

Required Space

Little

Objectives & Key Features

• Excreta containment
• Sludge volume reduction
• Reduction of odour and flies

Strength & Weakness

  • Flies and odours are significantly reduced (compared to non-ventilated pits)
  • Can be built and repaired with locally available materials
  • Low (but variable) capital costs depending on materials and pit depth
  • Small land area required
  • 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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