Water Supply and Access
Why is water supply important?
As a result of a number of past studies we began to develop a body of evidence which suggested that programs to improve water quality only are unlikely to have a significant health impact. Instead these studies suggested that a much greater health impact could be achieved by improving hygiene. One of the most simple and obvious ways to do so is to make it more water use more convenient and easy to access.
Being able to access water at a nearby location offers various other non-health benefits. It can often result in time savings – time that could instead be invested in education or increased work productivity. Secondly having a water point closer to home can potentially mitigate the security risks and vulnerability women and children often face when collecting water.
Our key contributions and research in this area:
The Water Use Plateau
This theory, which describes the relationship between the distance an individual must travel to reach a water source and the amount of water they consume, has been utilised by the EHG and others since the 1970s and was documented by Cairncross and Feacham in 1993.
According to this model, when water sources are more than half an hour’s return journey away from home, then provision of water closer to the home will lead almost automatically to water consumption increases, but sources less than a 30 minute round-trip away will be used for almost the same amount of water whether the distance is 1000 metres or 100 metres. Despite this inelasticity of demand, when water is piped into the house or yard, the convenience of access results in consumption rising dramatically. Based on this simple diagram, interventions to improve water supply should be targeted at those people who are ‘off the end of the plateau’ since closer water supplies will lead their consumption to increase – hence their hygiene to improve – and they will therefore be more likely to show a health benefit. For those on the ‘plateau’ it is only the installation of house connections that is likely to yield an increases in consumption and therefore a health benefit.
Despite acknowledging that water quantity is important to health, to date the Joint Monitoring Programme (JMP) which assesses progress towards the Millennium Development Goals on water and sanitation, only considers water quality as an indicator of an ‘improved water source’. This study utilised existing Demographic Health Survey (DHS) and Multiple Indicator Cluster Survey (MICS) data from 39 countries in sub-Saharan Africa to consider progress against the MDG indicator should distance to water source also be considered. The study found that with the subsequent inclusion of water collection time, the number of people with access to improved water sources within 30 minutes of their residence was 90 million, down from 160 million. This implies that 70 million people, roughly 10% of the region’s population, supposedly had access to ‘‘improved’’ water sources but had to spend well over 30 minutes to collect water from those water sources. It is arguable that those 70 million people effectively did not have access to water.
Our current projects in this area:
Bore hole provision in Pakistan
Currently we are collaborating with Osman Dar and Mishal Khan on a project in Pakistan which hopes to measure the health and non-health impacts of improving water access to those who are ‘off the edge of the plateau’ – those who travel for more than a 30-minute round trip to collect water. This will be an randomised intervention study which will provide bore holes in conjunction with a local Pakistani NGO.
This was an evaluation of Watershed’s piped water supply program in Vietnam. The study assessed the drinking water quality and health impacts of piped water systems where access to ‘improved’ water sources is already good. This was a longitudinal, prospective cohort study followed 300 households in seven project areas in Da Nang province, Vietnam. 224 households of these households paid for an on-plot piped water connection and 76 control households from the same areas rely on the existing ‘improved’ water sources outside the home. The evaluation found that households connected to a piped water supply had consistently better drinking water quality than those relying on other sources, experienced less diarrhoea.
Full list of publications related to water supply
- Bostoen K., Cairncross S. Monitoring of water supply coverage. In WELL factsheet. (2005)
- Water supply and sanitation: some misconceptions Cairncross S. Tropical Medicine and International Health. 2003 Mar; 8(3):193-5.
- Dar OA, Khan MS. Millennium development goals and the water target: details, definitions and debate. Trop Med Int Health. 2011;16(5):540-4.
- Fry K. Incorporating water quantity into the water access indicator: the effect on estimates of ‘adequate’ access to water for health in Sub-Saharan Africa. Msc Public Health Dissertation. (2008)
- Water supply, sanitation and hygiene promotion. Disease Control Priorities Project, Working Paper no. 28.
Cairncross, Valdmanis V. 2004. Washington DC: National Institutes of Health.
- Reviewing the health impacts of improvements in water supply. Lewin S, Stephens C, Cairncross S. Urban Health Newsletter. 1997 Mar; (32):34-47.
- Population density, water supply and the risk of dengue fever in Vietnam: cohort study and spatial analysis. PLoS Medicine. Wolf-Peter Schmidt, Motoi Suzuki, Vu Dinh Thiem, Richard G White, Ataru Tsuzuki,Lay-Myint Yoshida, Hideki Yanai, Ubydul Haque, Le Huu Tho, DangDuc Anh, Koya Ariyoshi (2011)
- Subaiya S, Cairncross S. 2011. Letter. Response to Wang and Hunter: A Systematic Review and Meta-Analysis of the Association between Self-Reported Diarrheal Disease and Distance from Home to Water Source. Am J Trop Med Hyg. 84(3):504
- Cairncross, S. 1997. Quantity or quality? Water supplies and health. People and the Planet 6, 3, 10-11.
- Cairncross, S. and Kinnear, J. 1992. Elasticity of demand for water in Khartoum, Sudan. Social Science and Medicine 34,2, 183-189.
- Cairncross, S. and Kinnear, J. 1991. Water vending in urban Sudan. Journal of Water Resources Development 7,4, 267-273.
- Aziz, K.M.A., Hoque, B.A., Cairncross, S. et al. 1990 Water supply, sanitation and hygiene education: report of a health impact study in Mirzapur, Bangladesh. Water and Sanitation report Series No.1. WashingtonDC: The World Bank.
- Cairncross, S. 1988. Domestic water supply in rural Africa. In: Rural Transformation in Tropical Africa, D. Rimmer, ed. London: Belhaven Press.
- Cairncross, S. 1987. The International Water Decade. Editorial, Lancet (ii), October 17
- Cairncross, S. 1987. The private sector and water supply in developing countries: partnership or profiteering? Health Policy and Planning 2 (2): 180‑182.
- Cairncross, S. and Cliff, J.L. 1987. Water use and health in Mueda, Mozambique. Transactions of the Royal Society of Tropical Medicine and Hygiene 81: 51‑54.
- Bostoen K, Kolsky P, Hunt C. 2007. Improving urban services: Indicators of access and the implication of boundaries. In: Marcotullio PJ, McGranahan G, editors. Scaling urban environmental challenges: From local to global and back. London, Sterling (VA): Earthscan.