Groundwater quality in Africa

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Africa Groundwater Atlas >> Resource pages >> Groundwater Quality 

Please cite page as: Africa Groundwater Atlas. 2023. Groundwater Quality. British Geological Survey. Accessed [date you accessed the information]. Weblink.

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Some general resources for understanding and managing groundwater quality

There are many resources discussing groundwater quality, some in great detail. However, to date there are few studies on groundwater quality across Africa as a whole, and no regional or national assessments.

Some useful overviews include:

This report describes why, and how, groundwater quality is vital to human health, agriculture, industry and the environment.
This policy brief highlights the key messages for policy makers from the World Bank report “Seeing the Invisible: A Strategic Report on Groundwater Quality” (Ravenscroft and Lytton 2022), describing the types of contaminants in groundwater, and techniques to protect the resource from being contaminated in the first place.

Drinking water quality guidelines

Where groundwater is used for drinking, it is important that it meets safe standards to avoid damage to human health. The World Health Organisation sets out guidelines for drinking-water quality (2017), which apply to all waters, including groundwater, used for drinking.

Groundwater quality fact sheets

Short, practical fact sheets summarising inorganic groundwater quality in a number of countries have been produced by the British Geological Survey (BGS) in collaboration with WaterAid. These also identify inorganic chemical constituents of risk to health that may be present in groundwater in each country. The BGS have also produced separate fact sheets summarising selected chemical elements that are particularly important to groundwater quality; and some summarising the impacts of selected human activities on groundwater quality. All of these fact sheets can be downloaded from the BGS website at the sites below:

  • Download fact sheets for groundwater quality for these countries in Africa: Burkina Faso, Ethiopia, Ghana, Madagascar, Malawi, Mali, Mozambique, Nigeria, Tanzania, Uganda and Zambia.
  • Download water quality fact sheets by element for these chemical elements of particular relevance to groundwater: arsenic, fluoride, iodine, manganese and nitrate. These element sheets aim to explain the nature of the health risk for each constituent, the origin and occurrence in groundwater, the means of testing and available methods of mitigation.

Geogenic contamination

Geogenic contamination refers to naturally occurring elements that are generally present in groundwater due to dissolution of the aquifer material. Geogenic contaminants in groundwater can have a negative effect on human health, particularly when consumed over prolonged periods of time. The most common geogenic contaminants are fluoride and arsenic. More than 300 million people worldwide are thought to use groundwater contaminated with fluoride or arsenic as a source of drinking water.

  • The British Geological Survey fact sheets give an overview of arsenic, fluoride, iodine and manganese, all of which can be geogenic contaminants in groundwater.
  • The Swiss Federal Institute of Aquatic Science and Technology (Eawag) has developed a method to assess the risk of groundwater contamination by fluoride or arsenic in a given area, using geological, topgraphical and other environmental data. The Groundwater Assessment Platform (GAP) enables users to upload their own data and generate hazard maps for specific areas. The Groundwater Assessment Platform also hosts a Wiki site where you can find and share information about geogenic contamination, associated health risks, and mitigation options.

Further information on the methodology used by Eawag can be found in these publications:

Salinity

Salinity is an important groundwater quality issue that can be driven by both natural and anthropogenic processes. Processes such as sea-level rise and intense evaporation can lead to naturally high salinity in groundwater, while overabstraction, irrigation and waste disposal can exacerbate groundwater salinity issues. Salinity has important consequences for human health and agricultural productivity.



Nitrate

Nitrogen occurs naturally in the environment and is essential for plant growth. Nitrogen-based fertilisers are therefore often applied to increase crop yields. Leaching from agricultural land can lead to high concentrations of nitrogen in groundwater, which can have a negative impact on both the environment and human health.

  • A British Geological Survey nitrate fact sheet is available giving an overview of nitrate in groundwater.

Urban pollution

Urban and peri-urban areas are expanding in many parts of Africa, particularly across sub-Saharan Africa. Groundwater is often a very important source of improved drinking water in urban and peri-urban environments, but high population densities put pressure on urban groundwater resources, not only in terms of quantity but of water quality.


Groundwater quality can be influenced by a large number of contaminants in the urban environment, from microbiological pathogens and heavy metals to macronutrients, herbicides and pesticides.


Some of the key sources of urban pollution include:

  • pit latrines, which are often located close to abstraction points, particularly in densely populated peri-urban or unplanned urban settlements
  • sewer leakage and sewage effluent
  • uncontrolled disposal of household and industrial waste
  • peri-urban agriculture, which includes pesticides/fertilisers and livestock waste
  • storm water runoff
  • vehicle emissions, power stations and mine waste


Urban groundwater issues in Africa are receiving increasing research attention in recent years, with more and more studies of both large and small cities and towns, and increasing detail in the chemical, microbiological and other groundwater quality parameters being studied.

Some overview studies of urban groundwater quality in Africa are:

Lapworth, DJ., Nkhuwa, DC.W., Okotto-Okotto, J. et al. 2017. Urban groundwater quality in sub-Saharan Africa: current status and implications for water security and public health. Hydrogeology Journal 25, 1093–1116


Africa Groundwater Atlas >> Resource pages >> Groundwater Quality

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