DESIGN, CONSTRUCTION, OPERATION AND MAINTENANCE OF VENTILATED IMPROVED PIT TOILETS IN SOUTH AFRICA
Report No 709/1/00
This report emanates from the Water Research Commission project number K5/709 entitled "Preparation of standard engineering drawings, specifications and guidelines for ventilated improved pit latrines in South Africa".
At present, Ventilated Improved Pit (VIP) toilet systems installed in South Africa are constructed according to a wide variety of designs and with many different types of materials, with a corresponding diversity of performance level and user acceptability. Some designs are of a good standard, but many toilets have been installed which do not function properly and are therefore unpleasant to use. Fly control is often inadequate and factors such as poor construction, high temperatures and bad odours can contribute to negative user experience and subsequent perceptions of the systems as second-rate or inferior.
It is generally accepted that the government cannot afford to provide conventional waterborne sanitation to all communities lacking this facility, at least for the foreseeable future. The majority of communities are also not in a position to provide or maintain such systems themselves. However, because of the strong link between sanitation services and public health, it is imperative that a programme which encourages an adequate basic level of sanitation, which is also largely affordable, be actively pursued in order to reach the communities who have little or no sanitation facilities.
Although it is clear that VIP toilets, correctly designed and constructed, offer an affordable and practical sanitation option to the majority of rural and peri-urban communities, there remains much ignorance regarding the proper engineering of VIP toilets. The authorities responsible for commissioning sanitation programmes, as well as various funding agencies involved in such schemes, do not always have at their disposal the necessary tools to enable them to make informed decisions or choices and consequently are often left with a legacy of poorly engineered sanitation systems. Guidelines for the design and construction of VIP toilets will assist such organizations in setting acceptable minimum standards.
The original aim of this project was to improve the standard of VIP toilets in South Africa by providing responsible organizations with the necessary information to enable them to plan, design, construct and maintain VIP toilets in an effective and sustainable manner. Hence, the following documents were intended to form part of this project:
However, due to the length of time which elapsed, as well as various other eventualities, the guideline documents as stated above have not been completed as part of this project. Guideline (a) has been replaced by a document entitled "Building VIPs: Guidelines for the design and construction of domestic Ventilated Improved Pit toilets". This document, published and distributed by the Department of Water Affairs and Forestry , is based largely on the research carried out as part of this project. Guideline (b) was eventually considered as being superfluous due to the existence of other documents of a similar nature. An attempt was made to produce Guideline (c), but due to the differing interpretations of illustrations, etc by various illiterate or semi-literate communities in the country , it was concluded that it would not be feasible to produce a document of this nature which would be applicable countrywide. It is suggested, rather ,that each project be evaluated on its merits and suitable posters or other explanatory materials produced for the specific communities by involving them in the actual process.
The output of this project, as far as the Water Research Commission's original contract with CSIR Building and Construction Technology is concerned, is therefore only this research report.
Issues that were identified as being of cardinal importance for community acceptance of VIP toilets are as follows:
Particular attention was paid to these aspects during the research phase of the project.
The research report includes a brief introduction to personal hygiene, which highlights the health dangers inherent in human faeces and the importance of using toilets and of washing hands. The disease-carrying role of flies is also pointed out. It is further emphasised that three integral factors, which must coexist, are of importance in promoting community health, namely:
The operational principles of both VIP and VIDP toilets are discussed in detail, covering important factors such as proper ventilation as well as fly and odour control. This is followed by a number of illustrated examples of VIP toilet designs from Botswana, Zimbabwe, Lesotho, Tanzania and Brazil, as well as various South African examples. An in-depth discussion of research findings and recommendations regarding the various components of a VIP toilet is then presented, covering the following aspects:
The issue of contamination of groundwater by VIP toilets is addressed. Recommendations from the available literature regarding pit depths and safe distances between pit toilets and water sources are summarised, while measures to prevent pollution from taking place are also included.
Regular maintenance of VIP toilets is essential if they are to continue functioning as they should and remain in an attractive and acceptable condition for use. The research report emphasises cleanliness and prompt attention to matters such as fixing of cracks, termite control, stormwater diversion, fly screen care, treatment of doors and hinges, as well as mosquito control. Factors affecting the rate of solids accumulation are listed and attention is drawn to the fact that disinfectants should not be put into the pit.
Pit emptying is often a problem if toilets are not specifically designed to facilitate the process. While mechanical emptying may be a solution in some urban areas, it is rarely an option in rural areas, and also has certain construction implications.
Finally, the issue of population density and its implications for choice of sanitation technology is addressed. The literature yielded certain guidelines on maximum population densities for single pit and twin pit toilets; however, attention is drawn to the problem of progressive loss of ventilation as the number of dwellings increases.
In conclusion it is stated that the Ventilated Improved Pit Toilet, when correctly designed, operated and maintained, has proved to be an acceptable, cost-effective, hygienic and environmentally friendly sanitation system. While there are always certain disadvantages associated with any sanitation technology, if the required attention is paid to all the diverse aspects involved, particularly the social and cultural aspects, then there is no reason why VIP toilets should not become perfectly acceptable to the vast majority of people who do not presently enjoy the benefits of a well designed and constructed toilet.
It is recommended that the Water Research Commission disseminates these findings to all organizations involved in the provision of sanitation. It is further recommended that the Commission actively supports the guideline document for design and construction of VIP toilets, distributed by the Department of Water Affairs and Forestry, as these guidelines are a direct outcome of this research project.