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< prev - next > Water and sanitation Sanitation KnO 100435_Collapsing Latrine Pits (Printable PDF)
Unstable soils
Two of the most common reasons for not building latrines are
collapsing soil and high water-tables, often in combination with
each other.
For unstable soils the following measures can be taken:
Use round pits
Introduce pit linings
Reduce pit dimensions
1. Round pits
In areas where there is a tradition of building latrines the population have already discovered
that round pits are more stable than rectangular ones.
In Malawi, for example, where the soil is generally stable, the population as a rule dig
rectangular pits. An exception is at the lake shore where pits, as a rule, are round because the
sandy soil is less stable. The same is true in Mozambique: in the areas along the coast, the
round pit is the only shape you will find, whereas inland people dig rectangular pits. You will
find the same phenomenon in most places in Eastern and Southern Africa.
When asking why this is the case, few people refer to soil stability, but instead give tradition as
a reason. In areas with mixed soil conditions, where the soil is less stable, there are often no
latrines. It may be tempting to propose round pits for all situations as strength is an advantage
and the cost seems to be the same. Covering a narrow rectangular pit is, however, simpler,
especially if the availability of long, strong logs is a problem.
The same kind of logic also works for latrine slabs of concrete. Round slabs are generally cast
on-site, while rectangular slabs can easily be segmented and transported in pieces.
2. Introduce pit linings
Round pit linings are very stable and can be made relatively cheaply, while rectangular pit
linings are structurally unsound and need to be made with strong
building materials. Pit linings should therefore normally be made
round. The material used will depend on what is available and
Lining with burnt bricks
Burnt bricks, when available and affordable, are very good for pit-
lining. Cement or mud mortar in horizontal joints are
recommended as the bricks may break under the load of the slab
and the superstructure.
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