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pic=Single_pit.png|
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Input1=Excreta|Input2=Faeces Blackwater |Input3=Anal cleansing waterFaeces| Input4= Anal Cleansing Water |Input5=Dry Cleansing Materials|Output1=ExcretaSludge | Output2=Faecal sludge | Output3= | Output4= | Output5=|english_link=Single_Pit|french_link=Latrine_traditionnelle|spanish_link=Pozo_Simple
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|[[Image:Single_pit.png |right|300px500px]]
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'''The Single Pit is one of the most widely used sanitation technologies. Excreta, along with anal cleansing materials (water or solids) are deposited into a pit. Lining the pit prevents it from collapsing and provides support to the superstructure.'''
As the Single Pit single pit fills, two processes limit the rate of accumulation: leaching and degradation. Urine and anal cleansing water percolate into the soil through the bottom of the pit and wall , while microbial action degrades part of the organic fraction.
'''Design Considerations''': On average, solids accumulate at a rate of 40 to 60L 60 L per person/year and up to 90L 90 L per person/year if dry cleansing materials such as leaves, newspapers, and toilet or paper are used. The volume of the pit should be designed to contain at least 1,000L000 L. Ideally Typically, the pit should be designed to be is at least 3m 3 m deep and 1 m in diameter. If the pit diameter exceeds 1.5m 5 m, there is an increased risk of collapse. Depending on how deep they are dug, some pits may last up to 20 or more years without emptying. To prevent groundwater contamination, the bottom of the pit should be at least 2 m above groundwater level (rule of thumb). If the pit is to be reused , it should be lined. Pit lining materials can include brick, rot-resistant timber, concrete, stones, or mortar plastered onto the soil. If the soil is stable (i.e. no presence of sand or gravel deposits or loose organic materials), the whole pit need not be lined. The bottom of the pit should remain unlined to allow the infiltration of liquids out of the pit.
Pit lining materials can include brick, rot-resistant timber, concrete, stones, or mortar plastered onto the soil. If the soil is stable (i.e., no presence of sand or gravel deposits or loose organic materials), the whole pit need not be lined. The bottom of the pit should remain unlined to allow for the infiltration of liquids out of the pit. As the effluent liquid leaches from the Single Pit pit and migrates through the unsaturated soil matrix, faecal organisms pathogenic germs are sorbed to the soil surface. In this way, pathogens can be removedprior to contact with groundwater. The degree of faecal organism removal varies with soil type, distance travelled, moisture and other environmental factors and , thus, it is difficult to estimate the distance necessary distance between a pit and a water source. A minimum horizontal distance of 30m between the pit and a water source is normally recommended to limit exposure to chemical and biological microbial contamination.
When it is impossible or difficult not possible to dig a deep pitor the groundwater level is too high, a raised pit can be a viable alternative: the depth of the shallow pit can be extending extended by building the pit upwards with the use of concrete rings or blocks. This adaptation A raised pit can also be constructed in an area where flooding is sometimes referred frequent in order to as a cesspitkeep water from flowing into the pit during heavy rain. It Another variation is a raised shaft on top of a the unlined shallow pit with an open bottom that allows may be appropriate for areas where digging is difficult. When the collection of faecal sludge and the leaching of effluent. This design howevershallow pit is full, is prone to improper emptying since it may can be easier to break or remove the concrete rings covered with leaves and allow the faecal sludge to flow out rather than have it emptied soil, and disposed of properlya small tree can be planted (see Arborloo, D.1).
A [[Single Ventilated Improved Pit|Ventilated Improved Pit]] (VIP, S.3) is slightly more expensive than a single pit, but greatly reduces the nuisance of flies and odours, while increasing comfort. If a urine-diverting User Interface is used, only faeces are collected in the pit and leaching can be minimized.
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Another variation is the unlined shallow pit that may be appropriate for areas where digging is difficult. When the shallow pit is full, it can be covered with leaves and soil and a small tree can be planted. This concept is called the Arborloo and is a successful way of avoiding costly emptying, while containing excreta, and reforesting an area. The Arborloo is discussed in more detail on the [[Fill and Cover - Arborloo]] section.
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{{procontable | pro=- Can be built and repaired with locally available materials.<br> - Does not require a constant source of water.<br> - Can be used immediately after construction. <br> - Low (but variable) capital costs depending on materialsand pit depth. <br> - Small land area required. <br> | con=- Flies and odours are normally noticeable. <br> - Sludge requires secondary treatment Low reduction in BOD and/or appropriate dischargepathogens with possible contamination of groundwater. <br> - Costs to empty may be significant compared to capital costs. <br> - Low reduction in BOD Sludge requires secondary treatment and pathogens/or appropriate discharge.
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===AdequacyAppropriateness=== Treatment processes in a single pit (aerobic, anaerobic, dehydration, composting or otherwise) are limited and, therefore, pathogen reduction and organic degradation is not significant. However, since the excreta are contained, pathogen transmission to the user is limited.
===Health Aspects/Acceptance===
A simple Single Pit is an improvement to open defecation; however, it still poses health risks:
* Leachate can contaminate groundwater;
* Stagnant water in pits may promote insect breeding;
*Pits are susceptible to failure/overflowing during floods.
Single Pits pits should be constructed at an appropriate distance from homes to minimize fly and odour nuisances and to ensure convenience and safe travelsafety.
===Upgrading===
A [[Single Ventilated Improved Pit|Ventilated Improved Pit (VIP)]] is slightly more expensive but greatly reduces the nuisance of flies and odours, while increasing comfort and usability. For more information on the VIP please refer to the [[Single Ventilated Improved Pit|Single Pit VIP]] page. When two pits are dug side-by-side, one can be used while the contents of the other pit are allowed to mature for safer emptying. For more information on dual pit technologies refer to [[Double Ventilated Improved Pit|Double Pit VIP]] and [[Twin Pits for Pour Flush]] pages.
===Operation & Maintenance=== There is no daily maintenance associated with a simple Single Pitsingle pit apart from keeping the facility clean. However, when the pit is full it can be a) pumped out and reused or b) the superstructure and squatting plate can be moved to a new pit and the previous pit covered and decommissioned, which is only advisable if plenty of land area is available.
===Field experiences===
{|style="border: 2px solid #e0e0e0; width: 7040%; text-align: justify; background-color: #f5f5f5e9f5fd;" cellpadding="2"<!--rsr logo here-->|- style="vertical-align: top"|[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr/]]<!--project blocks here-->|- style="vertical-align: bottom" |[[Image:rsr 476.jpg|thumb|nonecenter|200px140px|<font size="2"><center>[http://rsr.akvo.org/project/476/ RSR Project 476]<br>Ensure access to safe water and sanitation</center></font>|link=http://rsr.akvo.org/project/476/]]|'''Akvo RSR Project[[Image:''' rsr 819.jpg|thumb|center|140px|<font size="2"><center>[http://rsr.akvo.org/project/476819/ Ensure access to safe water and sanitationRSR Project 819]Salinity<br>Water, arsenic, lack of proper IWRM, and incidence of natural disasters in the three districts of the Southwest coastal belt of Bangladesh cause a lot of socioeconomic and health related problemsFood & Sanitation for School + Community</center></font>|link=http://rsr. The programme is right-based and strengthens knowledge and capacity of community WASH groups as well as local government institutions. As problems are multifaceted, the programme uses a multi-pronged strategy and facilitates partnership with existing institutional stakeholders relevant for WASH sectorakvo.org/project/819/ ]]
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===References ===
* ARGOSS (2001). [http://nora.nerc.ac.uk/id/eprint/20757/1/ARGOSS%20Manual.PDF Guidelines for Assessing the Risk to Groundwater from on-Site Sanitation]. British Geological Survey Commissioned Report, CR/01/142, Keyworth, UK.
* BrandbergFranceys, BR., Pickford, J. and Reed, R. (19971992). Latrine Building[https://www. susana.org/_resources/documents/default/2-1651-who-a-guide-to-the-development-of-on-site-sanitation.pdf A Handbook for Implementation Guide to the Development of the Sanplat Systemon-Site Sanitation]. Intermediate Technology PublicationsWHO, LondonGeneva, CH. (A good summary of common For information on accumulation rates, infiltration rates, general construction problems and how to avoid mistakes.example design calculations)
* FranceysGraham, RJ., Pickford, JP. and ReedPolizzotto, RM. L. (19922013). [https://pubmed.ncbi.nlm.nih.gov/23518813/ Pit Latrines and Their Impacts on Groundwater Quality: A guide to the development of on-site sanitationSystematic Review]. WHOEnvironmental Health Perspectives, Geneva. (For information on accumulation ratesNational Institute of Environmental Health Sciences, infiltration ratesResearch Triangle Park, general construction and example design calculationsUS.)
* LewisPickford, JW., et alJ. (19821995). The Risk Low Cost Sanitation. A Survey of Groundwater Pollution by on-site Sanitation in Developing CountriesPractical Experience. International Reference Centre for Waste DisposalIntermediate Technology Publications, DübendorfLondon, SwitzerlandUK. (Detailed study regarding the transport Book; Information on how to calculate pit size and die-off of microorganisms and implications for locating technologies.technology life)
* Morgan, P. Robens Institute (20071996). Toilets That Make Compost[http: Low-cost, sanitary toilets that produce valuable compost for crops in an African context//helid. Stockholm Environment Institute, Swedendigicollection. (Describes how to build a support ringorg/en/d/Js13461e/foundation3.4.html Fact Sheets on Environmental Sanitation. Fact Sheet 3.4: Simple Pit Latrines]. University of Surrey, UK and WHO, Geneva, CH.)
* Pickford, J[http://www. (1995)who. Low Cost Sanitation. A Survey of Practical Experience. Intermediate Technology Publications, London. (Information int/water_sanitation_health/publications/guidelines-on-sanitation-and-health/en/ WHO: Guidelines on how to calculate pit size sanitation and technology life.)health - 2018]
===Acknowledgements===
{{:Acknowledgements Sanitation}}