2001 Professor David Bradley: John Snow in the world of today

Professor David Bradley gave the ninth in the series of Pumphandle lectures of the John Snow Society on 5 September 2001 at the London School of Hygiene and Tropical Medicine (LSHTM).

The subject of the lecture was particularly appropriate to the memory of Dr John Snow and to the ‘pumphandle’ theme celebrating interventions and innovations in epidemiology and public health. Professor David Bradley’s long association with the LSHTM includes becoming Director of the Ross Institute in 1974 and he has an international reputation for his work on malaria and also on water. It was water that dominated his lecture on this occasion, with a summary and update of the classic study of domestic water use in East Africa (White, Bradley and White 1972). Professor Bradley paid tribute to Dr John Snow as the father of evidence based environmental health, for example in Snow’s emphasis on the importance of good drainage and on ample supplies of water free from sewage contamination. This goal still eludes over 2 billion people in developing countries (WHO 2001), nearly 150 years after the outbreak in Broad Street, which Snow used to complete his analysis of the spread of cholera in contaminated water in 1854. Professor Bradley argued convincingly for the unification of approaches to health and the environment and concluded his reflections on water with the symbolic importance of water in art, beautifully illustrated by drawings and paintings from around the world.

The study in East Africa 30 years ago was the first comprehensive survey of domestic water use, involving households and sites in Uganda, Kenya, Tanzania and Rwanda. The important findings included the high cost of water and the wide range of water volume used, with marked differences between those receiving piped and unpiped supplies. Those with piped water used between 10-650 litres per head, compared with 4-40 litres per head in areas with no piped supply. The cost of water was high: for example, 10% of the income of unskilled workers in Mulago (Uganda). Piped water in Africa cost the equivalent of 26 days’ salary a year, whereas in water-rich USA it cost only 1-2 days’ salary a year. Water consumption was closely linked to distance from the water supply and the study showed that it fell only when the users were more than a mile away. The study also examined cultural aspects of water use, for example restriction of bathwater in the home to men and the role of children in carrying water. The outcome of the study was a revision of the agenda for water, going beyond traditional water quality issues to ex-amine improvements and to categorise water related disease by type of source and water use/access.

Thirty years later, John Thompson of the International Institute for Environment and Development in the UK and colleagues in East Africa conducted a follow-up study Drawers of Water II. Astonishingly, many of the old records used in Drawers of Water I were still available to be used as comparison. While revealing some changes for the better, such as a doubling of the years of education of the water users, the follow-up survey found that water cost had risen and the time taken to collect water, for those with unpiped rural supplies, had risen from an average 15.8 minutes to 25.3 minutes. The volume of water use had doubled and the number of trips per day had risen slightly, while the average distance to the water source was much the same. By contrast, the volume of piped urban water used had fallen. While the population in the study areas had increased, water use was in general more efficient and there had been a cultural shift in water carrying. Women carried the old style containers on the head: with new large plastic containers, it had become more acceptable for men to carry water to supplement supplies. The study also examined environmental changes in water use and storage, showing for example that changes to papyrus swamps in Uganda had encouraged breeding of Aedes gambii mosquitoes.

Drawers of Water I and II demonstrated the value of repeat studies and the ‘long focus’ needed to assess the impact of water on health and the environment. While environmental health action is still dominated by legal enforcement issues, comprehensive studies such as Drawers of Water I and II show the importance of cultural ‘hard points’ that restrict change, the effect of loss of community and the changing baselines that determine the water-health relationship. Social justice becomes as important a factor as epidemiological evidence when trying to improve water-related public health.

In the final part of his lecture, Professor Bradley explored why water appears so often in landscape painting and other forms of art. At one level, water represents a refuge or pleasant prospect; at an environmental level, the frequent portrayal of water in art also suggests recognition of the importance of water to our habitat. He finished by agreeing with the medical writer René Dubois that we should not try to conform to the environment created by social and technical innovations; but that we should instead design environments adapted to our nature. This was an inspiring conclusion to a brilliant lecture combining water themes of science, art, medicine, epidemiology, history, public and environmental health.

As for most previous lectures, it was standing room only in the lecture theatre and afterwards at the John Snow pub, where members gathered to celebrate the memory of Dr John Snow and to hold the annual general meeting of the Society. It was also an important occasion for the Royal Institute of Public Health (its name from January 2002), as the first lecture held since relocation of the John Snow Society to the Institute. The annual ceremony of removing and then replacing the pump handle was a reminder of the continuing challenges remaining to public health in water and in other fields.


  • White GF, Bradley DJ, White AU. Drawers of Water: Domestic Water Use in East Africa. Chicago, USA: University of Chicago Press, 1972
  • World Health Organization. Water for Health: taking charge. Geneva: WHO, 2001 (WHO/WSH/ WWD/O1.1). See also www.worldwaterday.org and www.who.int/water_sanitation_health