Compost toilets
Practical Action
be within the owners plot to prevent disputes later, especially important in very crowded
communities. A significant advantage of compost toilets is that their location is not
dependent on the location of sewers or gradients. They can be established in a confined space
either within or beside a human dwelling, whether it is a thatched hut or high rise apartment
block.
Construction
The compost toilet comprises a raised slab over two chambers. The chambers are built on the
ground, not in it. In very waterlogged areas, or those prone to flooding, a slightly raised plinth
can be made. The chambers are plastered with cement internally in order to waterproof them
and make compost removal tidier. Over each chamber there is a hole in the slab for faeces and
a funnel to receive the urine. In some toilets there is a trough in the centre of the slab,
between the two chambers over which the anal cleansing is performed. The anal cleansing
water trough and urine funnel is inter-connected and flow to an evaporative plant bed outside
the latrine.
In the simplest version, the chamber doors are closed by bricks and mud mortar, both of which
can be reused to close it again. However, ferrocement, timber, marine ply or other materials
may also be used where they are appropriate locally.
Fly screen cover at
the end of the vent
Vent pipe
Wash water
Faeces hole,
closed off
Urine hole
Faeces hole,
in use
Ash bucket
Urine drain
Evaporative plant bed.
Not all the plants are
shown in this illustration.
Cover
Compost chamber
Figure 3: Double chamber compost toilet with cut away wall to show interior, Sri Lanka
design. Illustration: Neil Noble / Practical Action.
The chambers are designed to have an accumulation time of about nine months to allow
thorough composting of the contents and elimination of pathogens. The compost produced is
an almost dry, crumbly, black product having a light, pleasant, earthy odour. There is no fly
nuisance or any odour problem and the toilets remain clean and pleasant to use. The plant
bed needs almost no maintenance and the only requirement is to cut back excessive growth
which can be chopped up and added to the compost chamber if required.
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