An exploration of sanitation in Dakar

With 780 million people lacking access to an 'improved water source' - piped household water connection, public standpipe, borehole, protected dug well, protected spring, rainwater collection (WHO-UNICEF) -worldwide, urban groundwater acts as a substantial contributor to accessible freshwater. Previously local rivers could be relied upon but as pollution becomes prolific and climate change causes drastic changes, they can no longer be used, groundwater though is a climate-resilient source of freshwater in sub-Saharan Africa . As urbanisation takes hold of areas of sub-Saharan Africa, which up until now have been rural, urban planning must consider the new structure of the built environment necessary to provide for all citizens and achieve the United Nations sustainable development goal 6, universal and equitable access to safe and affordable drinking water.

In many places surface water requires treatment (chlorination) before consumption, ground water drawn up from wells can provide clean drinking water without it having to be treated. Access to 'safe water' has improved drastically between 1990 and 2015 with 68% of sub-Saharan Africa now with access. If planning does not pre-empt the expansive urbanisation in sub-Saharan Africa, current infrastructures will be overwhelmed in settlements already in existence; piped water, sewage and waste disposal need to be able to adapt to increased pressure. 

I wanted to explore other regions within sub-Saharan Africa to access whether the problems I found in Kampala were present else where. Dakar, Senegal, relies on decentralised septic tanks and pit latrines for low cost sanitation much like areas of Kampala. The sustainable development goal to achieve access to adequate and equitable sanitation and hygiene for all by 2030 is intertwined with the need for clean water. As more people rely on groundwater more scientific data needs to be acquired in order to protect this vital natural source. The risk to groundwater quality derives from faecal effluent, rich in organic nitrogen (urea: CO (NH₂)₂), chloride, and pathogenic microorganisms, that drains from on-site sanitation such as pit latrines.

Figure 1: Above shows the distribution of observed faecal contamination of shallow groundwater by nitrate and Escherichia coli.

The Dakar region relies on the shallow urban unconfined Quaternary sand aquifer, it underlies a densely populated peri-urban area with a population estimated at 1.5 million inhabitants. Recent mapping studies estimated approximately 253,000 septic tanks in the area with densities ranging from 1 to 70 tanks per hectare. When heavy and extreme rainfall intensities occur sharp rises in soil moisture content and shallow ground water recharge serve to flush faecal waste from these septic tanks. Meaning that although groundwater is proposed to be a climate resilient source of fresh water it is more easily contaminated than previously thought. 

Low income cities such as Dakar and Kampala are not provided with conventional (high-cost) water supply and sanitation infrastructure as the investment is currently lacking in impoverished communities they are therefore left to find other options. Their current reliance on low-cost, on-site solutions to water supply and sanitation to serve these communities will continue as African cities continue to rapidly urbanise. Having explored case studies based in two sub-Saharan African countries I am now aware that the issue of water supply and sanitation is not restricted to particular regions or small areas, but is one that affects large populations of the African continent. If a problem is this prolific I wonder why more has not been done, why logistical frameworks have not been supported or why investment hasn't been given to smaller sanitation projects that could make all the difference.