Groundwater quality in Africa

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


Some general resources for understanding and managing groundwater quality

The quality of groundwater is as important as its quantity: groundwater must be of a suitable quality to make it a useful resource, and poor quality groundwater can also affect surface-water ecosystems. Groundwater quality includes natural chemical variations and the controls on these; and the effects of chemical and microbiological pollution from agriculture, industry and other human activities. Some groundwater quality issues have a long history, such as anthropogenic pollution from nitrate and bacteria from human and animal wastes; increases in salinity from sea water intrusion or irrigation effects; or metal pollution from mining. The natural occurrence of health-harming chemicals in groundwater in some geological environments - in particular, fluoride and arsenic - is known in many parts of the world, including parts of Africa, but may also occur in places as yet unrecognised. Other anthropogenic pollutants are new, such as pharmaceutical chemicals, and are the subject of research around the world, including in Africa.

There are many resources discussing groundwater quality, some in great detail. Some useful overviews include these reports:

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.

An overview report on general water quality (surface and groundwater) in Africa is Africa’s Water Quality: A Chemical Science Perspective, (Pan Africa Chemistry Network, 2010).


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. These guidelines are available in English, French and Spanish.

Groundwater quality summary 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.

Groundwater contamination and pollution

Groundwater contamination can occur from natural processes - known as geogenic contamination - or from pollution from anthropogenic sources. Some of the main activities that can lead to groundwater pollution are agriculture, industry (including mining) and human waste disposal, but there are many others.

One recent overview of groundwater contamination in sub-Saharan Africa is:

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 in many parts of Africa, and can have important consequences for human health and agricultural productivity. Groundwater salinity can be driven by both natural and anthropogenic processes. Processes such as sea-level rise and intense evaporation (common under tropical climates) can lead to naturally high salinity in groundwater, while over-abstraction, irrigation and waste disposal can cause groundwater salinity or make natural salinity issues worse.

Nitrate

Nitrogen occurs naturally in the environment and is essential for plant growth, but if it is present at high concentrations in groundwater or surface waters it can have a negative impact on both the environment and human health. Nitrogen-based fertilisers - both inorganic and organic (eg animal waste) are often applied to agricultural land in order to increase crop yields. Leaching from agricultural land can lead to high concentrations of nitrogen in groundwater.

  • A British Geological Survey nitrate fact sheet gives an overview of nitrate in groundwater.

Urban groundwater quality and 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 main 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:

Rural groundwater quality

Some recent research on groundwater quality in Africa

UPGro

The UPGro research programme from 2013 to 2020 included research into a number of aspects of groundwater quality in Africa, including drinking water quality from hand pumped boreholes; viruses in urban areas; new techniques for measuring microbial pollution; and ensuring suitable groundwater quality for self supply. UPGro research outputs relating to groundwater quality are here.

Other research

These are some examples of recent papers on aspects of groundwater quality in Africa (full references are in the Reference list, below):


References

The resources referred to on this page, and some others, are listed here:

Documents


Amini, M, Mueller, K, Abbaspour, K C, Rosenberg, T, Afyuni, M, Moller, K N, Sarr, M, and Johnson, A. 2008. Statistical modeling of global geogenic fluoride contamination in groundwaters. Environmental Science and Technology, Vol. 42, 3662–3668.

Amini, M, Abbaspour, K C, Berg, M, Winkel, L, Hug, S J, Hoehn, E, Yang, H, and Johnson, A. 2008. Statistical modeling of global geogenic arsenic contamination in groundwater. Environmental Science and Technology, Vol. 42, 3669–3675.

Edokpayi, JN, Enitan, AM, Mutileni, N. et al. 2018. Evaluation of water quality and human risk assessment due to heavy metals in groundwater around Muledane area of Vhembe District, Limpopo Province, South Africa. Chemistry Central Journal 12, 2.

GRIPP. 2019. The link between groundwater quality and drought in Southern Africa. GRIPP Project Brief

Healy, A, Tijani, M, Grönwall, J, Eichholz, M, Villholth, K, Mwango, F, Danert, K, Upton, K, Lapworth, D, Lalika, M, and Gicheruh, C. 2022. Urban Groundwater in Africa: a dialogue for resilient towns and cities. AMCOW Pan-African Groundwater Programme (APAGroP). Abuja Nigeria

Langenegger O. 1987. Groundwater quality in rural areas of Western Africa. World Bank Regional Water and Sanitation Group Western Africa

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

Lapworth, DJ, MacDonald, AM, Kebede, S, Owor, M, Chavula, G, Fallas, H, Wilson, P, Ward, JST, Lark, M, Okullo. 2020. Drinking water quality from rural handpump-boreholes in Africa. Environmental Research Letters 15(6). DOI 10.1088/1748-9326/ab8031

Masindi, V and Foteinis, S. 2021. Groundwater contamination in sub-Saharan Africa: Implications for groundwater protection in developing countries. Cleaner Engineering and Technology, 2

Pan Africa Chemistry Network. 2010. Africa’s Water Quality: A Chemical Science Perspective. The Royal Society of Chemistry, UK / Syngenta

Ravenscroft, Peter and Lytton, Lucy. 2022a. Seeing the Invisible : A Strategic Report on Groundwater Quality. Washington, DC. World Bank.

Ravenscroft, Peter and Lytton, Lucy. 2022b. Practical Manual on Groundwater Quality Monitoring. Washington, DC. World Bank.

Sorensen, JPR, Chibesa, M, Pedley et al. 2015. Emerging contaminants in urban groundwater sources in Africa. Water Research, 72, 51-63.

Verlicchi P and Grillini V. 2020. Surface Water and Groundwater Quality in South Africa and Mozambique—Analysis of the Most Critical Pollutants for Drinking Purposes and Challenges in Water Treatment Selection. Water 12(1):305.

World Bank. 2022. Groundwater Quality : A Strategic Approach. Washington, DC. World Bank.

World Health Organisation. 2017. Guidelines for drinking-water quality, 4th edition, incorporating the 1st addendum. 631pp, ISBN: 978-92-4-154995-0

Zhao Zhou. 2015. A global assessment of nitrate contamination in groundwater. Internship report for IGRAC.


Other resources

British Geological Survey: country fact sheets for groundwater quality

British Geological Survey: water quality fact sheets by element

British Geological Survey: fact sheets on the impact of agriculture, industry and urbanisation.

EAWAG Groundwater Assessment Platform



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