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<International Source Book On Environmentally Sound Technologies
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8.11.2 Case study 2: Composting Toilet Trial on Kiritimati

Introduction

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 I-Kiribati counterparts.

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.

Location

Kiritimati (Christmas 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 study.

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 application.

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 building;
  • material 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;
  • the two chambers each have a floor grate to allow drainage of liquid into a drainage tray below;
  • the 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;
  • the 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;
  • each 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.

 

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