Collapsing latrine pits
Practical Action
Lining with concrete blocks
Due to the production process, concrete blocks usually have exact dimensions. They can
therefore be used without mortar, being simply stacked along the sides of the pit. The top
courses should be fixed with cement mortar as the surrounding soil is often washed away with
heavy rams.
Lining with stones
Natural stone makes an excellent lining material which requires
no mortar except in the top layers. The strength of the stone
allows it to take a considerable load without breaking, while the
weight of the structure holds the stone in place. The top of the
lining may need to be set in mortar as the stones might
otherwise start falling away. If you are going to use a concrete
slab you may need some mortar anyway to fill the gap between
the slab and the lining.
Lining with concrete rings
Using concrete rings for pit-lining can be very expensive if normal well rings are used. They are
heavy to transport and difficult to set in place. Using segmented rings with interlocking joints
may be easier.
Lining with oil drums
Old oil drums are frequently used for pit-lining. After the bottom of
each drum has been cut out, they can be placed one on top of another
to line deep pits.
The small volume and the high cost of the drums make this method
fairly expensive. If the sides of the drums are not provided with
sufficient perforations, absorption of liquids can be a problem.
Another problem is that the sheet metal will eventually corrode and
collapse if the drums are too old.
The pit contents and the resultant gases in a latrine are very corrosive.
Lining with wooden baskets
Large baskets made of sticks and twigs can be put into the pit. The
expected lifetime is around two years but this depends on the material
used and whether there are termites.
If the back-fill around the pit is made with well compacted termite clay, a
very stable pit can be achieved in loose sandy soils. When dry, this clay
will form a firm pit lining even after the wood in the basket has been eaten
by termites.
3. Reduce pit dimensions
Apart from the shape, size also influences pit stability, and the risk of collapse. Pits with small
diameters are more stable than pits with large diameters.
In areas of unstable soil it may be tempting to compensate for the poor depth by making pits
wider to achieve a reasonable volume. This is only possible if the pit is lined. Lining material
may be difficult to find or too expensive to use. In such cases the solution is to reduce the pit
diameter.
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