POLICY BRIEF Groundwater Quality A Strategic Approach Vital but Invisible Key Messages Groundwater is central to human development and an essential component of adaptation to climate change. •• Groundwater accounts for 97 p ­ercent of global freshwater Research has revealed that groundwater contamination is resources and is essential to human and economic development. more extensive and harmful than p ­ reviously thought. In the It supplies drinking water for more than one-third of the world’s absence of dedicated action to address this aspect of ground- population, around 40 p ­ ercent ­ ercent of irrigation water and 25 p water ­management, the capacity of the resource to satisfy of industrial water (IAH n.d.). As water availability becomes current or future demand is ­increasingly compromised. more variable with ­ climate change, ­ groundwater provides a critical buffer in times of water s ­ ­ hortage and the importance of Deteriorating Groundwater Quality aquifers for water storage increases. ­ Threatens Human Development •• Groundwater quality is central to its utility. When compromised by naturally occurring contaminants or polluted by human Groundwater resources are being degraded worldwide, activities, the consequences for human health, agriculture, and threatening society’s ability to provide water for drinking, the economy are far reaching and can span generations, with agriculture, industry, and the environment. The drive disproportionately large impacts for the global poor. to increase food production has polluted many shallow •• The challenge and cost of cleaning up polluted groundwater or aquifers with nitrate and pesticides. In dry areas, these treating it in perpetuity are far greater than protecting it in the ­ impacts are aggravated by naturally present salinity and first place. The economic costs of these avoidable phenomena poor land and water management practices. Meanwhile, are measured in ­ hundreds of billions of dollars. many urban aquifers have been blighted by a century or •• Protecting and managing groundwater quality should be a more of industrial chemical mismanagement and improper priority for decision makers. Necessary institutional strengthening waste disposal. When groundwater is contaminated, either measures include a well-formulated legislative framework, an naturally or by human action, the consequences for health, adequate b ­ udget, and the recruitment of relevant expertise. agriculture, and the economy can be immense. •• Measurement of groundwater quality is temporally and spatially infrequent and inconsistent. More and better data will enable ­ Reducing Anthropogenic Contamination evidence-based decision-making to ensure groundwater’s ­ ­ sustainability today and into the future. Risk-based measures can limit the extent of anthropogenic contaminants—those that result from human action— which are incredibly diverse and destructive (see box 1). These contaminants range from petroleum leaks under local fuel stations; to a vast array of industrial chemicals, including polyfluoroalkyl substances (PFAS), a class of 3,500 industrial pollutants (dubbed “forever chemicals”) that are highly toxic, persistent, mobile, and bioaccumulating; to pesticides, many of which are known or suspected carcinogens and endocrine-disrupting chemicals (WHO 2019). While most anthropogenic pollution is highly localized, the exceptions are fecal pathogens which contaminate shallow groundwater beneath human settlements, and fertilizer nitrate, which is widely applied and can persist in groundwater for decades, accumulating to high levels as more nitrogen is applied to the land surface every year. Mitigating Geogenic Contamination There are fewer known geogenic (naturally occurring) contaminants in groundwater than anthropogenic contaminants. However, increased testing reveals geogenic contaminants are more widespread than initially assumed. They affect hundreds of millions of people, causing crippling and potentially fatal illnesses. In some countries, they contribute significantly to total morbidity (see box 2). Some contaminants, BOX 1. Growing Hazards of Anthropogenic Contamination 23% Share of groundwater bodies in the European Union classified as being of poor chemical status (Psomas et al. 2021). Although estimating the extent of anthropogenic contamination is difficult because of the legacy of undocumented soil pollution, this study warns of pervasive groundwater contamination, even in countries with strong groundwater protection measures. 1,000 The number of new chemicals released into the environment in the United States each year, or about three a day. Pollution does not decline with economic growth, and the range of pollutants tends to expand with prosperity. Keeping up with such a growing range of risks is difficult even in countries with significant resources and is markedly more challenging in those that are underresourced (Damania et al. 2019). BOX 2. Threat of Natural Contamination to Global Health 150 million Number of people worldwide affected by arsenic contamination in drinking water since the 1970s. Arsenic exposure causes a host of debilitating illnesses, including painful skin diseases, the impacts of which cascade beyond health. Adults who are unable to work are subject to social exclusion; many of their children are withdrawn from school and unable to marry. In the mid-1990s, arsenic was discovered to be a widespread natural contaminant in groundwater (Ravenscroft, Brammer, and Richards 2009). An estimated 1 million people died from arsenic poisoning in the two decades since, with excess deaths continuing to this day. 200 million Number of people at risk of disease from fluoride exposure in drinking water (EAWAG 2015). Fluoride contamination can cause dental and skeletal fluorosis in humans, which may lead to chronic pain and damage to joints and bones (Fawell et al. 2006). It primarily affects poor communities that rely on untreated and perhaps untested water supplies. Knock-on effects can trap households into multigenerational cycles of poverty. 100 million Minimum number of people estimated to be exposed to manganese contamination, which impairs intellectual development of children (Bouchard et al. 2011; Khan et al. 2012). However, some countries do not test for it or are practically unaware of the health impacts. such as arsenic, threaten the sustainability of irrigated agriculture, wells for decades, even after the original source of pollution has which has important implications for food security. Although stopped. Likewise, some health impacts may take time to appear. geogenic contaminants cannot be removed, they can be prevented For example, cancers induced by contaminants (such as arsenic) from causing harm to humans through treating contaminated may develop decades after exposure ceases. The legacy effects of supplies or developing alternative supplies. contamination can impact multiple generations by suppressing economic growth (see box 3). Legacy of Polluted Groundwater Responding to Contamination Events Regardless of the source of pollution, contaminants may travel slowly through the ground for years until intercepted by a Large-scale anthropogenic contamination (such as nitrate and pumping well. By this time, the stores of contaminants in the pesticides from agriculture and pathogens from inadequate soil are significant and can pollute aquifers and abstraction sanitation) requires government support and a community-level WATER GLOBAL PRACTICE | GROUNDWATER QUALITY 2 BOX 3. Economic Impact of Polluted Groundwater –30% Share of reduced economic growth because of a lack of clean water. When water pollution crosses a certain threshold, gross domestic product growth drops by as much as one-third because of impacts on health, agriculture, and ecosystems. (Damania et al. 2019). BOX 4. Mitigation and Remediation Costs US$1.23 billion Amount spent on water treatment, blending, and replacing water sources in the United Kingdom between 1975 and 2003 to address deteriorating water quality affecting almost half of the groundwater used for public supply (UKWIR 2004). US$150 billion to US$750 billion Cost of cleaning up known contamination of groundwater from industrial and municipal wastes in the United States (USEPA 2001). response to change practices and gradually reduce contaminant right regulatory framework, proper groundwater management inputs. Localized pollution, such as from industrial sites and urban reduces vulnerability to increased water scarcity while landfills, can often be stopped through improved operations or other optimizing investments in water supply infrastructure and preventive measures. systems. The best way to limit the damage from pollution, however, is to stop Improving Groundwater Quality Monitoring it from happening in the first place. The basic approach is to delineate source protection zones around abstraction points linked to the Improved monitoring is a precondition for all other actions and planning process so planners can identify where hazardous activities should be a top priority. Key actions: should be prohibited or permitted only with special precautions. • Develop a conceptual model to characterize the aquifer While some pollution is inevitable, its severity can be greatly reduced that illustrates groundwater flow and quality, its uses, and by following groundwater management best practices. These include its interaction with the surface environment and mapped mandatory groundwater monitoring (allows early detection), pollution hazards. participatory management of groundwater, maintenance of an active • Establish a baseline to define the initial state of the aquifer register of new chemicals (to enable an adaptive response), and a and so measure the effectiveness of interventions or identify regulatory regime that encourages voluntary remediation. This requires the presence of contaminants so they can be mitigated before effective site characterization and collaboration between the site owner harm occurs. and the regulator. Placing these actions in a risk-based approach will • Commission an external review of groundwater monitoring prioritize action when it is likely most effective in reducing harm and and management to identify reforms that align with avoid unnecessary expenses associated with blanket responses. The international best practices. difficulty and time necessary to remediate aquifers is why groundwater protection and monitoring is so important. The  groundwater crisis Reforming Legislation worsens when there are long gaps between the start of pollution, its discovery, and the start of remediation (see box 4). Precise requirements should be developed to fit the national context through a regulatory review. Key actions: Practical Actions to Prioritize Groundwater • Administer environmental impact assessments that consider Monitoring and Protection groundwater quality impacts. • Build risk assessments into the regulatory process to enable a Prioritizing groundwater protection and management provides targeted and proportionate response. benefits to managers, policy makers, and budget holders. • Establish groundwater protection measures as part of legally When groundwater quality monitoring is supported by the binding planning and land use controls. WATER GLOBAL PRACTICE | GROUNDWATER QUALITY 3 Strengthening Relevant Institutions Damania, Richard, Sebastien Desbureaux, Aude-Sophie Rodella, Jason Russ, and Esha Zaveri. 2019. Quality Unknown: The Invisible Water Crisis. Washington, Most countries have developed water resource institutions to deal DC: World Bank. doi:10.1596/978-1-4648-1459-4. with quantitative issues of surface water and require reform to EAWAG (Swiss Federal Institute of Aquatic Science and Technology). 2015. Geogenic better accommodate groundwater and water quality more broadly. Contamination Handbook: Addressing Arsenic and Fluoride in Drinking Water, Measures relating to groundwater quality include the following edited by C. A. Johnson and A. Bretzler. Dubendorf, Switzerland: EAWAG. actions: Fawell, J., K. Bailey, J. Chilton, E. Dahi, and Y. Magara. 2006. Fluoride in Drinking- Water. WHO Drinking-Water Quality Series. Cornwall: IWA Publishing. • Provide budgetary allocations for groundwater quality monitoring. IAH (International Association of Hydrogeologists). n.d. “Groundwater: More • Create an independent auditor to examine networks and about the Hidden Resource.” https://iah.org/education/general-public​ /groundwater-hidden-resource. Accessed February 17, 2022. records. • Implement a policy of public reporting. Khan, K., G. A. Wasserman, X. Liu, E. Ahmed, F. Parvez, V. Slavkovich, D. Levy, • Facilitate citizen science. J. Mey, A. van Geen, J. H. Graziano, and P. Factor-Litvak. 2012. “Manganese Exposure from Drinking Water and Children’s Academic Achievement.” Neurotoxicology 33: 91–97. Psomas, A., G. Bariamis, S. Roy, J. Rouillard, and U. Stein. 2021. Comparative Study About the Policy Brief on Quantitative and Chemical Status of Groundwater Bodies. Study of the Impacts of Pressures on Groundwater in Europe. Copenhagen: European Environment Agency. This policy brief highlights the key messages for Ravenscroft, P., H. Brammer, and K. S. Richards. 2009. Arsenic Pollution: policy makers from the World Bank report “Seeing A Global Synthesis. Chichester, UK: Wiley-Blackwell. the Invisible: A Strategic Report on Groundwater Ravenscroft, P., and L. Lytton. 2022a. “Seeing the Invisible: A Strategic Report on Quality” (Ravenscroft and Lytton 2022a). This Groundwater Quality.” World Bank, Washington, DC. report and “A  Practical Manual on Groundwater Ravenscroft, P., and L. Lytton. 2022b. “Practical Manual on Groundwater Quality Quality Monitoring” (Ravenscroft and Lytton 2022b) Monitoring.” World Bank, Washington, DC. describe the types of contaminants in groundwater, UKWIR (UK Water Industry Research). 2004. Implications of Changing tools and resources for their measurement and Groundwater Quality for Water Resources and the UK Water Industry: Phase 3: long-term monitoring, and techniques to protect Financial and Water Resources Impact. London: UKWIR. https://ukwir.org​ /eng/reports/04-WR-09-8--/67216​/Implications-of-Changing-Groundwater​ the resource from being contaminated in the first -Quality-for-Water​-Resources-and-the-UK-Water-Industry-Phase-3-Financial​ place. -and​-Water-Resources-Impact. USEPA (United States Environmental Protection Agency). 2001. Cost Analyses for Selected Groundwater Clean-up Projects: Pump and Treat Systems and Permeable Reactive Barriers. Washington, DC: EPA. https://www.epa.gov/remedytech​ References /cost-analyses-selected​- ground​water​-cleanup-projects-pump-and-treat​ -systems-and​-permeable. Bouchard, M. F., S. Sauvé, B. Barbeau, M. Legrand, M.-E. Brodeur, T. Bouffard, E. Limoges, D. C. Bellinger, and D. Mergler. 2011. “Intellectual Impairment WHO (World Health Organization). 2019. Preventing Disease Through Healthy in School-Age Children Exposed to Manganese from Drinking Water.” Environments Exposure to Highly Hazardous Pesticides: A Major Public Health Environmental Health Perspectives 119 (1): 138–43. Concern. Geneva: WHO. https://apps.who.int/iris/handle/10665/329501. Connect with the Water Global Practice www.worldbank.org/water worldbankwater@worldbank.org    @worldbankwater  blogs.worldbank.org/water © 2022 International Bank for Reconstruction and Development / The World Bank. Some rights reserved. The findings, interpretations, and conclusions expressed in this work do not necessarily reflect the views of The World Bank, its Board of Executive Directors, or the governments they represent. The World Bank does not guarantee the accuracy of the data included in this work. This work is subject to a CC BY 3.0 IGO license (https://creativecommons.org/licenses/by/3.0/igo). The World Bank does not necessarily own each component of the content. 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