Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
8.11.2 Case study 2: Composting Toilet Trial on
In June 1995 a trial of
composting toilets was initiated and funded on Kiritimati in Kiribati by
AusAID, the Australian government aid agency.
The trial was conducted by a multi-disciplinary team from the Centre for
Environmental Studies at the University of Tasmania in co-operation with
This summary of the 14 month
project on Kiritimati will demonstrate the technical, cultural, social and
economic issues that are involved in the introduction of composting toilets,
and suggest future directions.
Island) is a coral atoll in the Line Islands, in the Republic of Kiribati.
Kiribati is a small island nation of 33 coral atolls dispersed along the
Equator in the Central Pacific. There
are three groups of islands and atolls, and Kiritimati is the southernmost
atoll in a chain of islands known as the Northern Line. Islands Kiritimati has
a highly variable rainfall pattern with an average of about 860 mm per year.
Deterioration in the quality
of the ground water has occurred through localised over pumping of the lenses
causing 'upconing' of the underlying transition zone and seawater, especially
during periods of average or lower rainfall.
The ground water is also affected by bacteriological and chemical
pollution from human activities. Ground water can be polluted from sources such
as domestic animals particularly pigs and dogs, latrines and septic tanks,
greywater soaks, fuel storage, agricultural activities, and open rubbish and
Babai (taro) pits. The degree and
extent of pollution from these sources is not known and would merit extensive
The Kiritimati composting
toilet trial became part of the Water Supply project that had been planned
since 1982, and the recent inclusion of the trial reflected reluctance by the
donor government to reticulate contaminated water to the community.
It was considered that effective sanitation
should be attended to at the same time that the water supply implementation
took place. There is a high incidence
of enteric disease on Kiritimati and one source of transmission of these
diseases is likely to be as a result of faecally contaminated water.
The community is encouraged to boil the
water before consumption but this does not always happen.
Other sources of disease transmission would
be through lack of hand washing after defecation, and from flies that come in
contact with exposed faecal deposits.
Installation of pre-fabricated imported toilets
In November 1994, 12 toilets
were installed in three villages on Kiritimati.
The Wheelibatch toilets were
installed in domestic locations on Kiritimati and the two large Cage Batches
were installed at the primary schools in two of the villages.
One of the smaller Cage Batches was
installed at a community clinic that was being funded by the village residents,
and the other was installed in a domestic location where the extended family
members often numbered more than twenty.
Education/community consultation program
An education program was
undertaken to inform the community of the trial and to explain the use and
reason for composting toilets. As each
culture has different attitudes about sanitation, and each community has
different requirements and limitations, ongoing consultation with the residents
was a critical aspect of implementation.
The development of the education program was based on the advice and
assistance of I-Kiribati counterparts, the Community Health Educator and the
Assistant Health Inspector.
Introduction of new
sanitation technology in any culture is a complex and sensitive process as it
affects peoples' lives in the most intimate manner.
In Australia, the occasions when composting toilets have failed
has been due to a lack of an education component in implementation, or as a
result of inadequate pre-sales consultation and after-sales support.
In the Kiritimati context, the Australian
project team were somewhat handicapped by being unable to speak or understand
Kiribati and by being largely unaware of the variety of cultural and political
issues that affected the complex social mix on the island.
Installation of locally built toilets
During the reconnaissance
visit in June 1994, staff from the Ministry of Line and Phoenix Development
which administers island affairs expressed concern that use of the
prefabricated toilets would not be sustainable as supply would depend on aid,
and maintenance would be difficult due to lack of locally available spare parts
and expertise. The Australian project
team shared this concern and recommended to AusAID that more toilets be built
employing an owner-built design that they had used in Australia for domestic
Fortunately, the opportunity
arose for the construction of three more toilets because of a decision to
extend the trial to non-government housing.
Most of the trial participants for the 9 domestic toilets were transient
government employers (usually three year terms on Kiritimati), and it was
considered necessary to also trial the toilets at non-government houses where
people are long term residents and responsible for their own dwellings and
leased land. It was thought that the
response of these residents would be more likely to reflect that of the normal
I-Kiribati villager who owns his or her house-site and has a long term relationship
with the land.
The reasons given for
installing a local design at that stage of the trial were:
- increased local participation in, and
ownership of the project
- increased familiarity with the concept and
principles of composting toilets through owner-building
- increased likelihood of sustainable
maintenance due to the use of locally available materials
- avoid delay to construction which would be
caused by having imported materials shipped from Australia to Kiritimati
- allow a comparison in community response to
the pre-fabricated and locally built designs.
The agreement was that the
men of each household who were to receive the toilet would be involved in the
construction of their own toilet. When
the time came for the installations in May 1995, most of these men were working
on other building projects and so the construction team was composed of members
of the Mayor's family. The Mayor
provided invaluable assistance and support during this stage of the project.
As these locally built
alternating batch toilet designs are considered the most suitable for small
island conditions, details of materials, costing, installation and management
recommended in those circumstances follow.
Design features of locally built toilet
The locally built
dual chamber batch composting toilets are characterised by the following design
features: (See Figures 8.4 & 8.5)
- the toilet base comprises two adjacent chambers which each form a cube with
approximately 1m sides, the top of which forms the floor of the toilet
is deposited through a pedestal or squat plate into one chamber until it is
full and then that chamber is closed off to compost and the pedestal or squat
plate changed to the alternate side;
two chambers each have a floor grate to allow drainage of liquid into a drainage
drainage tray has a 50 mm outlet approximately 25 mm above the base of the tray
that allows a standing liquid level, and allows for access in case of blockage;
two chambers have hinged doors closing onto a frame which allows for a seal
against the entry of flies;
- the chamber doors have mesh covered vent holes which allow the entry of air but
offer a seal against the entry of flies;
chamber is vented with a vent pipe that extends from the top of the chamber to
approximately 1.5 m above the roof of the toilet building;
- the frame of the toilet building is
built on top of the two chambers with the stairs and the door on the opposite
side of the toilet building to the chamber doors.