SDG 6 targets “universal and equitable access to safe and affordable drinking water for all”. However, rapid urbanisation in coastal areas of developing countries combined with increased water use have become an issue for both water availability and quality.
In the region of Dakar, nearly “80% of water resources”, including drinking water, “come from groundwater sources” that extend over a large area in the suburban zone of Thiaroye, in Pikine (Re et al., 2010). These reservoirs are mainly part of a vulnerable unconfined aquifer (Diédhiou et al., 2011) that is increasingly affected by overexploitation, salinisation and anthropogenic pollution. Without adequate protection and long-term management, the water is declining rapidly and probably irreversibly, with a critical impact on ecosystems and human health.
By the 1980s, the water sector of Dakar had to provide increasing volumes of water in a situation of inadequate resources and infrastructures. Ineluctably, local water sources were insufficient and polluted, while population growth and agricultural and industrial development required more and more water. The government subsequently adopted a reform in 1996 that is presented as an environmental and social success by the authorities and the World Bank.
Yet the depletion and pollution of water resources proceed at an accelerated pace since the reform, while social inequalities remain.
First of all, “the continuous overexploitation” of groundwater increased its mineralisation and produced a decline in its quality, “with important drawbacks on health and agricultural development” (Re et al., 2010).
Moreover, the pressure on already insufficient sanitation infrastructure, especially sewage drainage systems, is one of the major sources of groundwater pollution in the region of Dakar. In some municipalities of the region, “most houses are equipped with improper septic tanks”, leaking into the groundwater (Re et al., 2010).
Furthermore, a large part of the population uses pit latrines and dumps waste, increasing pollutant concentration in water and significantly affecting seawater. Contaminated by discharges of wastewater with high concentration of trace metals, seawater then intrudes into groundwater (Diop et al., 2012).
In addition, agriculture and industrial activities are main drivers of the severe nitrogen contamination of groundwater. In Thiaroye, concentrations of nitrates close to 1400 mg/L have been measured (Diédhiou et al., 2011), whereas the drinking water limit is fixed at 50 mg/L by the WHO.
This deterioration of groundwater is primarily due to the high permeability of the aquifer and the proximity of industrial sources of pollution. At present, due to the high pollution level in the suburban area, many wells are closed, resulting in lowered pumping rate and thus recurrent flooding through rising groundwater table.
Nevertheless, many boreholes pumping in polluted tables still feed the distribution network of Dakar. This contaminated water “is officially diluted with better quality water”. For instance, “at the Thiaroye plant, water from the Thiaroye and Sebikotane tables is diluted with water from the Lake of Guiers” and clean tables (Theven de Gueleran, 2012). However, there is not any control of proportions, while the priorities are satisfying demand and ensuring pressure, leading to the absence of dilution at peak hours. Polluted water is therefore directly spilled into the network and ineluctably received by the poor peri-urban neighbourhoods which are closer to the boreholes.
From an environmental standpoint, water sources are now so polluted that they are mostly lost or so overexploited that they cannot renew themselves.
From a social standpoint, “access to drinking water increased from 79% in 1996 to 91% in 2006” in the Dakar area. Nonetheless, the reform left the low-income households with “unaffordable, insufficient and low quality supply”, in comparison with wealthy areas (Theven de Gueleran, 2012). Indeed, price increase and distribution in priority to zones with high demand leave the poor areas with irregular supply, low water pressure and polluted groundwater, while they cannot compensate availability problems with adequate storage and filtration.
In a nutshell, the water sector reform is not a success for everyone, especially not regarding environmental issues and social inequalities, since its worst effect since is to encourage the use of polluted underground water.
But instead of looking for new sources of freshwater, projects should focus on improving the quality of already available water through the development of treatment systems and sanitation facilities.