Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
1.3.2 Small-scale and community-scale technologies
In Lagos Island, an aerated lagoon was constructed in 1969 to
treat night soil wastes. The site now known as the night soil treatment plant is
currently being used by the local government as a fish pond. There is however a
plan to rehabilitate it and re-convert it into a treatment plant.
Table 1.14 presents a regional picture of the distribution of
on-site sewage disposal technologies, including VIP toilets, in use.
Table 1.14: Access to onsite sanitation facilities in
The composting system is one of the alternative sanitation
systems. Implicit to compost latrine technology is the notion of a dry
(waterless) on-site system that accepts human excreta which gradually breaks
down to produce a compost material that is safe for handling and disposal. It is
recent in South Africa, having come into existence only since 1993. During the
short period, its evaluation showed that Enviro Loo latrines performed
adequately and were accepted by users as a satisfactory alternative to communal
chemical toilets. Safety, privacy and accessibility are preferred aspects of the
system (Scott, 1998). In particular:
no adverse health impact was recorded among the users; and
no sludge removal is required, though pumping out of storm
water and grey water may be necessary.
the technology as practised in South Africa acts more like a
prolonged process of dehydration rather than a composting latrine. Further
treatment of the waste material is therefore advocated by evaluation, once
removed from the latrine container.
The most unfavourable aspect is that it does not flush!
Double-vault VIP latrine
Botswana’s Ministry of Local Government and Lands, together
with the Building Research Establishment in the UK has developed a double-vault
ventilated pit latrine for use in squatter areas and site and service schemes.
The VIP has been used in urban areas in Botswana since 1978. About 10,000 units
have been built in Botswana since 1978.
It consists of a shallow pit divided into two vaults, each having an effective
volume of 1.5m3. In stable soil, the pit is not lined. The covers are made of
precast concrete and are removable. Emptying can be done manually or
mechanically in a 3-4 year cycle. It is actually a cross between the
double-vault compost latrine and the pit latrine. Like the compost latrine, it
has the advantage of being permanent.
Reid’s Odourless Earth Closet (ROEC)
ROEC is a type of improved pit latrine developed in South Africa
and patented in 1944 (du McPherson, 1994). The pit is 1m x 2m and at least 3m
deep. It is covered with a concrete slab fitted with a 75mm diameter vent pipe.
Concrete slab to keep out flies
Water and sanitation present serious problem in Mozambique. Only
12% of the dwellings in Mozambique are directly supplied with drinking water.
Water is mainly supplied by public fountains. In urban environments, more than
70% of homes can obtain water from a communal network (public fountains), others
rely on rivers, ponds, wells and tank trucks. A rigorous latrine construction
campaign multiplied the number of latrines in Mozambique from 60,000 to 1.2
million. In 1984, 72% of urban dwellings were equipped, 93% in Maputo. Problems
include instability of the soils, high water table, and the failure of the
covers which were to keep out insects.
The squatting slab is the heart of any pit latrine, and the
drophole is a very important feature of the squatting slab. It is therefore
understandable that the government of Mozambique adopted a standard model of
latrine cover obtained by research in place of the former wooden covers. It is
1.5 m in diameter and made of reinforced concrete, circular and slightly
conical, and can easily be managed by one person. Its shape corresponds exactly
to that of the pit and provides a better cover than a simple slab. The pit is
raised up if the water table is high; it is built on breeze-block if the soil is
unusually unstable. The local authorities through the Directorate of
Construction and Town Planning of Maputo set up cooperatives in order to produce
Members of the cooperative were elected by local authorities
(the Facilitator Groups) affected. This coordinating committee
(Inter-Cooperative Management Committee) carries out many functions that used to
be performed by the government. Annual production of latrine covers was 18,000
in 1986, from cooperatives and workshops. Produced at a cost of Mt 500 (US$12),
the present need is 2,500,000 in urban and peri-urban areas. The number of
cooperatives and production centres continues to increase, and the project has
been replicated in other towns with a total annual production of more than
10million (Brandberg, 1985).
The project is largely dependent on international aid . It is
also overly dependent upon support of government policy which could compromise
its long term viability. The population must be more involved in the decisions
to give the organizations greater autonomy.
1The contact institution is Mazingira Institute,
P.O. Box 14550 Nairobi, Kenya.
Fax: 254-2-44 46 43.