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close this bookA Guide to the Development of on-site Sanitation (WHO; 1992; 246 pages)
View the documentPreface
close this folderPart I. Foundations of sanitary practice
open this folder and view contentsChapter 1. The need for on-site sanitation
open this folder and view contentsChapter 2. Sanitation and disease transmission
open this folder and view contentsChapter 3. Social and cultural considerations
close this folderChapter 4. Technical options
View the documentOpen defecation
View the documentShallow pit
View the documentSimple pit latrine
View the documentBorehole latrine
View the documentVentilated pit latrine
View the documentPour-flush latrine
View the documentSingle or double pit
View the documentComposting latrine
View the documentSeptic tank
View the documentAqua-privy
View the documentRemoval systems for excreta
open this folder and view contentsPart II. Detailed design, construction, operation and maintenance
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
 

Single or double pit

In rural and low-density urban areas, the usual practice is to dig a second pit when the one in use is full to within half a metre of the slab. If the superstructure and slab are light and prefabricated they can be moved to a new pit. Otherwise a new superstructure and slab have to be constructed. The first pit is then filled up with soil. After two years, faeces in the first pit will have completely decomposed and even the most persistent pathogens will have been destroyed. When another pit is required the contents of the first pit can be dug out (it is easier to dig than undisturbed soil) and the pit can be used again. The contents of the pit may be used as a soil conditioner.

Alternatively, two lined pits may be constructed, each large enough to take an accumulation of faecal solids over a period of two years or more. One pit is used until it is full, and then the second pit is used until that too is full, by which time the contents of the first pit can be removed and used as a fertilizer with no danger to health. The first pit can then be used again.

Advantages of single pits

Advantages of double pits

Will last for several years if large enough

Once constructed the pits are more or less permanent

 

Easy removal of solids from the pits as they are shallow

 

Pit contents can be safely used as a soil conditioner after 2 years, without treatment

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