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close this bookA Guide to the Development of on-site Sanitation (WHO; 1992; 246 pages)
View the documentPreface
open this folder and view contentsPart I. Foundations of sanitary practice
close this folderPart II. Detailed design, construction, operation and maintenance
open this folder and view contentsChapter 5. Technical factors affecting excreta disposal
close this folderChapter 6. Operation and maintenance of on-site sanitation
View the documentPit latrines
View the documentSimple pit latrines
View the documentVentilated pit latrines
View the documentVentilated double-pit latrines
View the documentPour-flush latrines
View the documentOffset pour-flush latrines
View the documentDouble-pit offset pour-flush latrines
View the documentRaised pit latrines
View the documentBorehole latrines
View the documentSeptic tanks
View the documentAqua-privies
View the documentDisposal of effluent from septic tanks and aqua-privies
View the documentComposting latrines
View the documentMultiple latrines
View the documentOther latrines
open this folder and view contentsChapter 7. Components and construction of latrines
open this folder and view contentsChapter. 8 Design examples
open this folder and view contentsPart III. Planning and development of on-site sanitation projects
View the documentReferences
View the documentSelected further reading
View the documentGlossary of terms used in this book
View the documentAnnex 1. Reuse of excreta
View the documentAnnex 2. Sullage
View the documentAnnex 3. Reviewers
View the documentSelected WHO publications of related interest
View the documentBack Cover

Pour-flush latrines

The problems of flies, mosquitos and smell in simple pit latrines may be overcome simply and cheaply by the installation of a pan with a water seal in the defecating hole (Fig. 6.8). Chapter 7 gives details of the design and fabrication of water seals. The pan is cleared by pouring (or, better, throwing) a few litres of water into the pan after defecation. The amount of water used varies between one and four litres depending mainly on the pan and trap geometry. Pans requiring a small amount of water for flushing have the added advantage of reducing the risk of groundwater pollution. The flushing water does not have to be clean. If access to clean water is limited, laundry, bathing or any other similar water may be used.

Fig. 6.8. Pour-flush latrine


WHO 91427

Pour-flush latrines are most appropriate for people who use water for anal cleaning, and squat to defecate, but they have also proved popular in countries where other cleaning materials are common. However, there is a likelihood of blockage where solid materials such as hard paper or corncobs are put in the pan. The placing of solid cleaning materials in a container for separate disposal is not generally recommended unless careful attention can be given to the handling of the waste and sterilizing of the container. Blockage may also be caused by material used by menstruating women. This should be disposed of separately, e.g., by burying or burning. Efforts to clear blockages often result in damage to the water seal.

In most cases, because of the small quantity of water required for flushing, pour-flush latrines are suitable where water has to be carried to the latrine from a standpipe, well, or other water source. There is no justification for the belief that the pit should be ventilated to prevent the build up of gases. A vent pipe adds to the cost of the latrine and any gases produced easily percolate into the surrounding soil.

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