REPORT NO: 925/1/03

February 2003


Background and motivation

In South Africa, one fifth of the population (7 million people) does not have access to an adequate supply of potable water, and one half of the population (21 million) lacks basic sanitation. It is estimated that there are approximately 24 million incidences of diarrhoea per year in South Africa, of which 2.8 million require treatment at health care facilities and 43 000 people die. The South African Government and water-related agencies are undertaking a vigorous campaign to provide 'water for all'.

The evaluation of the effectiveness of the interventions on disease morbidity and mortality is a challenging task, as the linkages between water and health are complex. Many contend that the introduction of a water supply scheme does not necessarily result in improved health. The most important reason for the international research in this area is that preventable diarrhoea is perceived to be the cause of many deaths worldwide. If the causes of the diarrhoea can be identified and addressed, thousands of lives, especially those of children, would be saved.

Most studies on the effects of water supply on human health over the past fifty years have been criticized as to their validity and usefulness. lack of adequate control, poor project design, many confounding variables, cultural bias, health indicator recall, health indicator definition and failure to analyse by age have been sited as rendering study results meaningless. Eminent researchers in the field, such as Caimcross, are equally sceptical. While instinctively it is accepted that water and sanitation do improve health, there are many opinions as to how and why.

It has been proved that the quantity of water has a greater impact on health than water quality. An improvement to the proximity of water supply (piped water) not only increases the quantity of water used, but also removes the need for water storage and therefore contamination. This may in turn reduce contamination and the proliferation of disease bearing vectors such as mosquitoes and flies. Owing to the varied results of international research in this field, more South African research was required to:

Aims and objectives as specified in contract

The original title was: "Assessing the causes and pathways of waterborne disease in rural settlements with limited formal water supply and sanitation"

Study design

The Stepped Wedge Design was suggested as an appropriate study design due to the progressive nature of the development over time. The four surveys corresponded where possible to the four phases of the introduction of water supply to the four different areas. Confounding factors were minimized through the selection of settlements located in the same area. Characteristics, such as the sanitation infrastructure, quality of the local water resources, topography, natural physical characteristics, distance from urban areas, settlement density, socio-economic levels, demographic and educational profile characteristics were recorded and expected to be similar. The selection of households to be surveyed was based on a stratified random approach and the number required was based on an anticipated improvement in diarrhoeal prevalence of 15%, with a 95% confidence interval.

The Epi-info software package was used to capture the data. A team of two research assistants were tasked to sample the 100 households in Vulindlela, visiting each household five times over a 15-month period in January 1999 to March 2000. A Zulu speaking social scientist was responsible for administering all the health questionnaire surveys and water quality samples were collected from the storage containers and water sources of the 100 household sample.

Brief summary of results and conclusions

Overall, there was no direct correlation proved between water quality and diarrhoea per se. However, there was a marked decrease in diarrhoea with the introduction of the new water supply. There was definite correlation between hygiene behaviours and diarrhoea.

Extent to which objectives were reached and actions to be taken as a result of the findings


he objectives above were refined after consultation with the steering committee and the words in brackets removed, as well as "sanitation", as there were no study sites available within a reasonable distance, where sanitation interventions were planned. Government subsidies for sanitation had been exhausted. The original title was also modified by the steering committee, to better describe the content of the report, in the light of the above changes to the objectives. All of the above-refined objectives were achieved as described in the conclusions, products and recommendations contained in this report.

Diarrhoea would seem to be the health impact associated with water, of choice. The most important reason for the international research in this area is that preventable diarrhoea is perceived to be the cause of many deaths worldwide. If the causes of the diarrhoea can be identified and addressed, thousands of lives, especially those of children, would be saved.

This study has provided many lessons regarding study design and the efficiency of using epidemiological studies as a health impact assessment tool in the water sector. Although double-blinded randomised trials are considered the gold standard for evaluation, it is very difficult to conduct a truly randomised trial for environmental interventions, such as a water supply. There is no placebo for water and in many communities; a cluster effect is experienced because the whole community benefits from the water supply although the Stepped Wedge Design provides some innovative features, which overcome some of the problems. In conclusion, the experience of this study in Vulindlela indicates that the epidemiological approach is fraught with difficulties, which make it difficult to draw firm conclusions.

The research products provided are:

Suggested improvements to water supply interventions:

  1. Taps need to be situated inside the house to prevent storage of any sort, which leads to contamination.
  2. The point above will necessitate the provision of a drainage system for public health reasons.
  3. Hygiene education be addressed as the causes of diarrhoea would appear to be correlated with many basic hygiene procedures, rather than water quality.
  4. A post- construction audit process be introduced to assess all aspects of the scheme to assess its effectiveness in operation, appropriateness and its effect on health.

Recommendations for further research and technology transfer

Given the difficulties experienced with epidemiological studies as outlined above it would seem that observational/behavioural methods are better suited. Behavioural components should not be dismissed as cultural idiosyncrasies as there is no Public Health intervention without behavioural change. It is possible to make three recommendations:

  1. A generalized Health Impact Assessment Guideline be developed and evaluated for use in assessing health factors in a water supply scheme. Some water utilities are already using a series of key performance indicators to evaluate and monitor rural supply schemes. Current indicators include service performance, financial performance and accountability indicators. Health related indicators would be a valuable addition to such a protocol.
  2. Patterns of hygiene behaviour be evaluated for adding to the list of key performance indicators. The WHO Minimum Evaluation Procedure suggests that health improvements are the culmination of a long chain of events from the original construction, through operation and use, which in turn permit changes in hygiene behaviour and possible prevention of disease. Patterns of hygiene behaviour may prove more reliable than measuring disease rates or water quality.
  3. Define feasible, acceptable and cost-effective approaches to delivering the intervention

It is recommended that the results of this study be distributed to various authorities involved in policy decisions for water and sanitation supply and health policies, such as the Department of Water Affairs and Forestry; Departments of Health (local, regional and national); and District Municipalities. Feedback to the community involved in this study should be provided, possibly through local radio and environmental health officers. The following papers were presented at conferences.

Papers presented:

L Archer, IW Bailey, G Xaba, C Johnson. An evaluation of the impact of reticulated water on community and environmental health in Vulindlela, KwaZulu-Natal. WISA Biennial Conference Sun City, 2000
IW Bailey. The relationship between water quality and public health in developing countries; health impact and economic assessment from the provision of rural water supply in South Africa. IWA Health-Related Water Microbiology Symposium, Paris 2000
IW Bailey, L Archer. The impact of introducing treated water on aspects of community health in a rural community in KwaZulu-Natal South Africa. Submitted to IWA Health-Related Water Microbiology Symposium Cape Town September 2003
Posters presented:
G Xaba, L Archer, C Johnson, IW Bailey. Community concerns regarding the implementation of water supply in a rural area in KwaZulu-Natal. WISA Biennial Conference Sun City, 2000
C Johnson, M Colvin, L Archer, IW Bailey G Xaba. Measuring the health impact of water supply -challenges of methodology. WISA Biennial Conference Sun City, 2000

Archiving of Data

The detailed results and raw data are retained at Umgeni Water, Pietermaritzburg.