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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
open this folder and view contentsChapter 6. Operation and maintenance of on-site sanitation
close this folderChapter 7. Components and construction of latrines
View the documentPits
View the documentLatrine floors
View the documentSlabs
View the documentFootrests and squat holes
View the documentSeats for latrines
View the documentWater seals and pans
View the documentVent pipes
View the documentSuperstructure
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

Seats for latrines

In many parts of the world, people prefer to sit to defecate. To make a latrine seat, a support or pedestal is built or mounted on top of the slab. The seat level should be at a position that is comfortable for the majority of the users (Fig. 7.26); this is normally about 350 mm above the top of the slab.

Fig. 7.26. Latrine seat


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The seat support can be made on site from brick, concrete, mud block or timber and should be designed to minimize the load on the slab. A heavy type of construction adds weight to the slab which then requires more expensive reinforcement to carry the load. Commercially available or project-manufactured pedestals made of ceramic, glass-reinforced plastic (GRP), PVC or ferrocement can also be used where people can afford them.

The inside of the pedestal should be designed to prevent constant fouling by excreta, which leads to increased odour and fly breeding. One approach is to use a large-diameter opening of 250 mm or more, but this might discourage use by children who are frightened by the large opening. An alternative is to have a 180-mm diameter hole through the pedestal which is lined with a smooth material such as cement mortar or an insert of glass fibre (Fig. 7.27) or ceramic. A third alternative is a tapered hole, increasing from an opening size of about 180 mm at seat level to 300 mm at the slab. If possible the pedestal should overhang slightly so that the seat can be used with the feet tucked under to mimic the squatting position.

Fig. 7.27. Pedestal seat liner (A)


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Fig. 7.27. Pedestal seat liner (B)


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Shapes of locally made pedestals vary from a rectangular box, where the user sits on one side but can also sit across a corner with one foot on either side, to a circular or oval design. It is important to obtain a good seal between the pedestal and the slab.

A seat cover may be fitted to seal off an unventilated pit. Where a vent pipe is fitted, an adequate flow of air to the pit can be obtained by raising the seat cover slightly above the seat, as is the case with conventional flush pedestals.

A special fitment with a small opening can be made to encourage children to use the latrine. Alternatively the pedestal top can be enlarged to accommodate a second seat with a smaller opening, possibly at a lower level, for the use of children.

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