Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
Evapo-transpiration trench(See Figure 8.5)
The purpose of
the evapo-transpiration trench is to ensure that excess liquid that is drained
from the toilet does not reach the surface or contaminate the ground
water. This is achieved by:
- sizing the trench such that the probability
of surcharging is very low;
the top and adjacent areas with species that will maximise evapo-transpirati
from the trench.
- bunding and raising the trench to
prevent surface run-off into the trench and to maximise rainfall run-off from the
top of the trench.
Figure 8.4 Composting toilet used in Kiribati
Figure 8.5: Evapo-tranpiration trench
Food crop trees,
such as papaya, banana or breadfruit can then be planted adjacent to the
trenches to further assist evapo-transpiration.
Plants or trees which provide bulking agent could also be planted
unit cost of the locally built composting toilets on Kiritimati including the
toilet building based on the specified design is AUS$2,500 to AUS$3,000.
This includes all materials, I-Kiribati
labour costs and the liquid drainage trench requirements.
From the results
of the education component in the sanitation pilot on Kiritimati, it is
recommended that an incentives package be offered to encourage the widespread
acceptance and use of the composting toilet on the island and to effect an
understanding of the direct relationship between sanitary habits, water quality
and hygiene, and the connection with health and nutrition.
This package should include a well fenced
garden area, seed, trees and plants and gardening assistance and advice.
This strategy may not be an effective
educational tool in some other cultural context, and community feedback will
indicate which strategy is most appropriate in each application. What can be
undertaken is, of course, also dependent on available funds and resources.
Results of the trial
The sanitation project was
conducted from June 1994 to September 1995, to ascertain whether the composting
toilet was appropriate to Kiritimati from a cultural, technical and
environmental point of view. An
appraisal team of four consultants visited the island to assess the trial in
September 1995. The prefabricated
toilets had been trialed for ten months and the locally built units were
trialed for 3 months prior to the appraisal. The trial project team recommended
that this was much too short a trial period to fully cover all the issues
involved. However there was
considerable pressure to proceed with the long delayed Water Supply project and
now that it entailed a sanitation component it was necessary to proceed with
the larger Water and Sanitation strategy as soon as possible.
A survey was conducted and 258 households
out of 316 said they would like a composting toilet.
It was decided that the 'pilot' trial had been sufficiently
successful to justify an extended trial of some 200-300 composting toilets with
the intention that the whole island would eventually be using composting toilets.
Usage of the prefabricated toilet during the 10 months that the Wheelibatch
and Cage Batch toilets were trialed usage slowly increased in the domestic applications.
Given the number of people in the households it was obvious from the rate at
which the bins filled up that only a percentage of the household were using
the toilets in the early stages. The women were more inclined to use the toilets
as they offered some privacy. Teenage boys reported that they were embarrassed
to be seen entering the toilets. The men preferred to use the bush or the beach.
After the video was shown throughout the community, usage increased. Toward
the end of the trial some families reported that everyone was using the toilet
including the men. The gardening program resulted in a significant increase
in the trial participants' interest in the composting toilets.
Usage of locally built
toilets was much more consistent from the outset.
It appeared from the rapid rate at which the bins filled up that
all household members were using the toilet.
This may have been due to the more integrated design and it may also
have been due to the toilets being within the non-government village and being
built by village residents.
At the schools, the usage
was consistently low for a number of reasons.
The toilet was rather conspicuous and the children were sometimes teased
for using it. The teachers insisted on
locking the toilet so the children had to ask the head teacher for the
key. As many of the children have chronic
diarrhoea this would have been a demanding requirement.
Most of the teachers did not use the compost
toilet but continued to use flush toilets in the teachers nearby houses, which
would not have provided very encouraging example to the children.
The teachers became more interested in the
composting toilet through the gardening program.
It is thought that when a greater number of people have
composting toilets at home the children will feel less conspicuous using the
toilets at school.
Taboos related to sorcery
and faeces were a concern with regard to containing excrement in a bin that may
be accessible to prohibited persons. Certain taboos relating to menstruating
women using the toilets were also raised.
However these issues did not seem to be a problem within the family and
as the trial progressed, people became more comfortable using the toilet
regardless of these concerns. At the
outset of the trial, there was a definite aversion to the prospect of using the
end product for fertiliser or any other method of disposal that might allow
contact. It was difficult for people to
believe that excrement would be transformed into an acceptable material.
However when the piles in the toilets did
actually produce compost there was a relieved and surprised response, and a marked
increase in interest in the toilets. Neighbours to trial participants, who had
previously been disinterested or even hostile to the project, requested a
composting toilet because they wanted to be able to have a garden and use the
compost as a soil improver.
People objected to the
height of the buildings. They said they felt uncomfortable using a toilet,
which was elevated, above ground. Some
said they feared that a person may be underneath. This probably relates to the
traditional use of latrines that are suspended over water.
The height of the buildings caused
embarrassment to some people because they were conspicuous when they climbed
the stairs and used the toilet.
A request was made by
householders that the toilet doors be made lockable in case strangers used
their toilet. However most people lost
their keys within a short time and so the toilets then remained unlocked,
except for the schools and the clinic.
During the reconnaissance trip in June 1994, the community was asked whether
they would prefer squat plates or pedestals for the toilets. Most people replied
that they would prefer pedestals but it was indicated that in fact many people
would still wish to squat, so a compromise was made by designing a low pedestal
which allowed sitting in a semi-squatting position. The pedestal was also made
strong enough to support considerable weight for squatting on the seat if desired.