The Importance of John Snow for Water and Sanitation in Urban Sub-Saharan Africa

In 1854 during the great cholera epidemic in London, John Snow had begun investigating outbreaks of cholera in Soho, London. The dominant theory at the time was that cholera was spread through pollution or a noxious form of ‘bad air’ as part of the miasma theory, but Snow was very skeptical at the time. After speaking to residents in London, he identified the Broad Street water pump in Soho to be of issue, and convinced the local authority to disable the pump. Later, he then drew up a point map in the area, with each point signifying a cholera case. The map showed clear clustering in the area around where people used the Broad Street pump for much of their water supply.

John Snow cholera map. Source

  It was then discovered that the public well had only been dug 3 feet from an old cesspit that had begun to leak faecal bacteria. One of the primary causes was that a baby who had contracted cholera from another source had its nappies washed into the cesspit (Cameron and Jones, 1983). John Snow’s discovery was pivotal in the acceptance of the oral-fecal method of transmission of disease.

Application in Sub-Saharan Africa

The demonstrated link between water and health using the faecal-oral paradigm found that drinking water contaminated by excreta causes diarrhoeal disease and gastrointestinal illness, which is one of the main causes of death in developing countries. Key to combating this is the improved supply of water and sanitation facilities, by improving the treatment of water and domestic hygiene.

The consequences of not having access to safe water and sanitation are epidemics of diarrhoeal disease, including outbreaks of cholera, E. Coli and cryptosporidium. These occur at more than one location involving anomalous increase in incidence. Cholera typically lives in swamps, lakes and rivers, as well as unprotected wells and springs, which is why there are often many outbreaks in Sub-Saharan Africa. Mutation of disease can also be triggered by extreme events such as storms.

What can be an effective sanitation solution in Sub-Saharan Africa?

Over 80% of people in urban areas of Sub-Saharan Africa are served by on-site sanitation technologies (Strande et al., 2014). Sub-Saharan Africa requires low cost solution as such settings lack financial strength (Morella et al., 2008), and therefore the building of a complete sewerage system such as those in London, Paris and New York is not feasible. However, it is still vitally important for adequate sanitation facilities to be available, to avoid excreta contaminating water supply, and viability of on-site sanitation technologies depends on adequate management of accumulated faecal sludge (Semiyaga et al., 2015). In differing areas, there is a choice between a community pit latrine or a household septic tank, but this obviously varies in affordability and suitability in an area. According to the World Bank, a pit latrine will cost $39 per capita, while a septic tank will cost $115 per capita in Africa. Geology in particular plays a huge role in how effective sanitation is, as for example, Lusaka is built on limestone which is very porous. Although the porosity means that limestone is a great aquifer as water transmits very readily, there is very little attenuation and groundwater can easily be polluted (Baumle et al., 2012). As pit latrines in Lusaka are often built in these holes, sewage can get into the water supply virtually instantaneously.

As I’m slightly wary of making this post too long, I’m going to stop here and build from this post in my next one. My next post will be regarding EcoSan - or ecological sanitation - and of course featuring more of the gendered implications of unsafe water and poor sanitation. Stay tuned!