and the Efficacy of Pit Latrine Additives - Water Research Commission

Given the large uncertainty and variation that will be observed in field trials, there is a need for a
standardised protocol for testing the performance of the additives under controlled conditions. It is simply not
possible to replicate field conditions in a controlled manner. It is therefore a strong recommendation of the
project team that conclusions about the efficacy of commercial pit latrine additives be based on controlled
laboratory based experiments, rather than on field trials.
Finally, it was concluded that this study has shown no benefit in the use of pit latrine additives to accelerate
the rate of degradation of pit latrine contents under either aerobic or anaerobic conditions. Furthermore, it
was concluded that the financial cost of use of these additives was likely to be less than the cost of manually
emptying the latrine every 5 years provided an appropriate pit emptying programme was in place.
6.4 Design of pit latrines
The standard VIP design was found to be effective for the accumulation and degradation of faecal sludge.
However, it was observed that the ability of a VIP latrine to function as an improved sanitation system i.e. to
provide hygienic separation of human waste from human contact, to limit the transport of pathogens from
human waste by vectors such as rodents and insects, to reduce nuisance associated with flies and odour
and to preserve the dignity of the user, was compromised in a number of respects due to poor construction,
bad user habits, and during pit emptying operations. These were discussed in detail in Chapter 5 and are
summarised as follows:
It was observed that poor construction or lack of maintenance often resulted in essential features of the
VIP latrine design being missing or damaged, including vent-pipes, flyscreens, pedestal lids, doors and
back plates. Under these conditions, there were usually problems with odours and flies.
Bad user habits resulted in rapid accumulation of pit contents, particularly when poorly degradable anal
cleansing material such as magazines, plastic bags or stones were used. In many cases pit latrines
appeared to double as waste disposal sites, resulting rapid filling of the latrines.
During pit emptying operations, significant risk of infection of workers and community members with
human pathogens originating from the pit contents is expected due to difficulties in removing pit latrine
contents and separating faecal sludge from solid waste.
It was concluded that certain targeted interventions could improve the ability of the VIP to provide an
improved sanitation service to the users of the latrine:
Design changes relating to the volume of the pit and access to pit latrine contents could reduce the risk
of the spread of disease during pit latrine emptying operations.
User education should be implemented to ensure that pit latrines are properly used and maintained,
thereby eliminating many of the problems associated with VIP latrines including flies, odours and rapid
filling rates.
A detailed, budgeted and financed plan to empty pit latrines and manage the exhumed sludge should
be in place wherever VIPs form part of a Municipal or government plan for provision of improved
sanitation.
A supplementary programme should be in place in communities serviced with pit latrines to ensure that
spare parts are available for maintenance of the units, and sufficient expertise may be found within or
near to the community to undertake simple maintenance exercises identified by owners of the VIP
latrines.
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