This chapter assesses observed and projected climate-induced changes in the water cycle, their current impacts and future risks on human and natural systems and the benefits and effectiveness of water-related adaptation efforts now and in the future.
Currently, roughly half of worlds ~8 billion people are estimated to experience severe water scarcity for at least some part of the year due to climatic and non-climatic factors (medium confidence1 ). Since the 1970s, 44% of all disaster events have been flood-related. Not surprisingly, a large share of adaptation interventions (~60%) are forged in response to water-related hazards (high confidence). {4.1, Box 4.1, 4.2.1.1, 4.2.1.2, 4.2.2, 4.2.4, 4.2.5, 4.2.6, 4.3.8, 4.6, 4.7}
Intensification of the hydrological cycle due to human-induced climate change is affecting physical aspects of water security (high confidence), thereby exacerbating existing water-related vulnerabilities caused by other socioeconomic factors. {4.2, 4.2.1.1, 4.2.1.2, 4.2.1.3, 4.2.2, 4.2.4, 4.2.5, 4.2.6, 4.3}
Extreme weather events causing highly impactful floods and droughts have become more likely and (or) more severe due to anthropogenic climate change (high confidence). {4.2.4, 4.2.5, Cross-Chapter Box DISASTER in Chapter 4}
There is increasing evidence of observed changes in the hydrological cycle on people and ecosystems. A significant share of those impacts are negative and felt disproportionately by already vulnerable communities (high confidence). {4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.3.6, 4.3.8}
Water-related risks are projected to increase with every degree of global warming (high confidence), and more vulnerable and exposed regions and peoples are projected to face greater risks (medium confidence). {Box 4.1, 4.4.1, 4.4.1.1, 4.4.4, 4.5.4, 4.5.5, 4.5.6, Box 4.2}
Drought and flood risks and societal damages are projected to increase with every degree of global warming (medium confidence). {4.4.4, 4.4.5, 4.4.7, 4.5.1, 4.5.2}
Limiting global warming to 1.5°C would reduce water-related risks across regions and sectors (high confidence). {4.4.2, 4.4.5, 4.5.2, 4.5.3, 4.5.4, 4.5.6, 4.5.7, 4.6.1, 4.7.2}
Observed water adaptation responses have multiple benefits (high confidence), yet evidence of effectiveness of adaptation in reducing climate risks is not clear due to methodological challenges (medium confidence). {4.6, 4.7.1, 4.7.3}
Future projected adaptations are effective in reducing risks to a varying extent (medium confidence), but effectiveness falls sharply beyond 2°C, emphasizing the need for limiting warming to 1.5°C (high confidence). {4.6, 4.7.2, 4.7.3}
Water security is critical for meeting Sustainable Development Goals (SDGs) and systems transitions needed for climate resilient development, yet many mitigation measures have a high water footprint which can compromise SDGs and adaptation outcomes (high confidence). {4.1, Box 4.4, 4.6, 4.6.2, 4.6.3, 4.7, 4.7.1, 4.7.4, 4.7.5.7}
A common set of enabling principles underpinned by strong political support can help meet the triple goals of water security, sustainable and climate resilient development (high confidence). {4.8, 4.8.3, 4.8.4., 4.8.5, 4.8.6, 4.8.7}
4.1 Centrality of Water Security in Climate Change and Climate Resilient Development
Water security is defined as ‘the capacity of a population to safeguard sustainable access to adequate quantities of acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water-borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability’ (Grey and Sadoff, 2007). Risks emanating from various aspects of water insecurity have emerged as a significant global challenge. The Global Risks Report by the World Economic Forum lists water crisis as one of the top five risks in all its reports since 2015 (WEF, 2015; WEF, 2016; WEF, 2017; WEF, 2018; WEF, 2019; WEF, 2020). Water also features prominently in the SDGs (Section 4.8) and plays a central role in various systems transitions needed for climate resilient development. Most SDGs cannot be met without access to adequate and safe water (Ait-Kadi, 2016; Mugagga, 2016). In addition, without adequate adaptation, future water-related impacts of climate change on various sectors of the economy are projected to lower the global GDP by mid-century, with higher projected losses expected in low- and middle-income countries (World Bank, 2017; GCA, 2019).
Water quality has been closely related to human health 1 ever since John Snow linked a cholera outbreak in London to contaminated water in 1855.2Vibriocholerae in water still plays a big role in the annual 1.4-4.3 million cholera cases that continue to occur globally. 3 The SARS-CoV-2 virus, which caused the COVID-19 pandemic, also enters the water cycle, as some COVID-19 patients shed the virus with their stool. 4 Although SARS-CoV-2 has been detected in wastewater, and in surface water receiving untreated wastewater, 5 so far there has been no evidence for presence of viable or infectious virus particles in wastewater, or for water as a transmission source. 6 Instead, the European Union launched a study, coordinated by its Joint Research Council and linked to the World Water Quality Alliance, to explore the potential of wastewater-based virus remnants as a sentinel monitoring concept.
But pathogens are not the only problem. Water is contaminated in a number of other ways that can threaten human health. The toxic compound arsenic is widely present in groundwater and can lead to skin, vascular and nervous system disorders, and cancer. 7 Recent estimates show that 94-220 million people are exposed to high arsenic concentrations in groundwater. 8 Similarly, fluoride, nitrate, heavy metals, and salinity in (ground)water pose human health risks.
Biotoxins formed by some cyanobacteria are a particular nuisance because bloom-forming species accumulate at the water surface, requiring closure of bathing sites and drinking water intakes. 9 As well, a large number of organic micropollutants coming from manufacturing and agriculture pose a health risk to the population. 10These organic micropollutants can have a variety of impacts, such as disruption of endocrine, reproductive and immune systems. They can also cause cancer and diabetes as well as thyroid and behavioural problems . 11
More recently recognized contaminants influencing human health include antimicrobial resistant microorganisms (AMR), microplastics 12or nanomaterials. AMR are a concern worldwide 13because infections from them are often difficult to treat. Although the role of water in the spread of AMR is not yet quantified, its importance has been recognized. 14
The potential health risks from microplastics seem obvious, but knowledge of the extent to which they affect human health is limited. 15And, though recent focus has largely been on the marine realm, UNEP will soon publish guidance on monitoring and addressing plastics in freshwater. 16
Water quality is related to human health through exposure. People are exposed to water in many different ways, depending on their location, livelihood, culture, wealth, gender etc. The most common exposure ways can be summarized as drinking, bathing, ingestion during domestic use, eating irrigated vegetables, rice (or rice products) or aquatic plants (such as water spinach), eating contaminated fish and shellfish, and skin contact. These exposure pathways highlight that the quality of ground, surface and coastal waters is relevant to human health.
In an earlier assessment, Snapshot of the World’s Water Quality, 17faecal coliforms were the contaminant included to represent human-health impacts. The assessment concluded that the rural population at risk of health problems, which is defined as those in contact with water contaminated with high concentrations of faecal coliforms, could be up to hundreds of millions of people in Latin America, Africa and Asia. 18While this was an important realization, faecal coliform concentrations do not usually correlate very well with pathogen concentrations, as they can grow in the water body, 19and many more contaminants can have human-health impacts. Therefore, this current assessment incorporates more water quality variables and exposure routes to assess the impact of water quality on human health.
Results
To evaluate the direct and indirect impacts of water quality on human health, we developed a non-exhaustive overview (see Table 3.1). This showed that there are a large number of direct and indirect links between water quality and human health, as well as interrelations between water quality variables, their sources, state, impacts and response. For example, pathogens and nitrate have to some extent the same sources and, therefore, potentially similar response options. But quantitative evidence for the links between water quality and human health are still largely lacking at continental or larger scales.
The global freshwater quality database GEMStat has data for a number of contaminants, but these data vary in space and time. For example, faecal coliform data are available for 6,451 stations across the world, while Escherichia coli data are available from 3,790 stations in North America, South America, Japan, and New Zealand. Data for Salmonella are available for 62 stations along rivers in Europe, but only for a few years in the early 1990s. For arsenic, many heavy metals, nutrients and organic micropollutants some data are available in GEMStat. Here we do not evaluate these data, because they are scattered and recent data for health are scarce. Instead, we report on potential data analyses that have been performed.
Table 3.1The influence of water quality on human health. This list is non-exhaustive, as no detailed literature has been performed. The colour coding is blue for GEMStat or other large-scale databases; red for remote sensing; yellow for modelling; and green for a combination of GEMStat and modelling. Dark colours are for surface water, light colours for groundwater.
Microplastics (MPs), defined as plastic particles smaller than 5 mm, are an emerging global environmental and health concern due to their pervasive presence in aquatic ecosystems. This systematic review synthesizes data on the distribution, shapes, materials, and sizes of MPs in various water sources, including lakes, rivers, seas, tap water, and bottled water, between 2014 and 2024. Results reveal that river water constitutes the largest share of studies on MP pollution (30%), followed by lake water (24%), sea water (19%), bottled water (17%), and tap water (11%), reflecting their critical roles in MP transport and accumulation. Seasonal analysis indicates that MP concentrations peak in the wet season (38%), followed by the dry (32%) and transitional (30%) seasons. Spatially, China leads MP research globally (19%), followed by the USA (7.8%) and India (5.9%). MPs are predominantly composed of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments being the most common shapes. Sub-millimeter MPs (<1 mm) dominate globally, with significant variations driven by anthropogenic activities, industrial discharge, and environmental factors such as rainfall and temperature. The study highlights critical gaps in understanding the long-term ecological and health impacts of MPs, emphasizing the need for standardized methodologies, improved waste management, and innovative mitigation strategies. This review underscores the urgency of addressing microplastic pollution through global collaboration and stricter regulatory measures.
The growing intrusion of microplastics (MPs) into water supply networks, exacerbated by their physicochemical features that facilitate their movement in water and enable microbial attachment, represents an under-recognized but rising threat to public health. The present work is a scooping review that synthesized recent studies to explore the roles of MPs as dynamic pollutants that not only contaminate water sources and distribution systems but also interact with bacterial contaminants in ways that intensify health threats. In accordance with SDG 6 (Clean Water and Sanitation), we examined the sources and fate of MPs in water distribution networks, their mechanisms of transportation, and their function as surfaces for bacterial attachment and biofilm development. We paid attention to how MPs can carry harmful bacteria and store genes that make bacteria resistant to antibiotics, which could help these bacteria survive and spread throughout the water distribution system, an issue related to SDG 3 (Good Health and Well-being). These microplastic-associated biofilms called plastisphere can compromise water quality assessments, escape conventional water treatment procedures, and aggravate the distribution of antimicrobial resistance. Furthermore, we highlight the limits of existing detection and monitoring methods for MPs and related bacterial threats in water. We ascertain serious knowledge gaps in understanding the long-term behaviour of MPs in real-world water distribution conditions, particularly under variable hydraulic and environmental stresses. Addressing these gaps require imminent research focus on in situ studies of MP-bacterial interactions, innovative molecular and sensing machineries, risk valuation models that integrate microbial and genetic information (SDG 9: Industry, Innovation, and Infrastructure). Interdisciplinary collaborations among environmental microbiologists, water engineers, and public health workers could also help to develop a standardized, high-resolution detection protocols.
Water is life. Yet, as the world population mushrooms and climate change intensifies droughts, over 2 billion people still lack access to clean, safe drinking water. By 2030, water scarcity could displace over 700 million people. From deadly diseases to famines, economic collapse to terrorism, the global water crisis threatens to sever the strands holding communities together. This ubiquitous yet unequally distributed resource underscores the precarious interdependence binding all nations and ecosystems and shows the urgent need for bold collective action to promote global water security and avert the humanitarian, health, economic, and political catastrophes that unchecked water stress promises.
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The global water crisis refers to the scarcity of usable and accessible water resources across the world. Currently, nearly 703 million people lack access to water – approximately 1 in 10 people on the planet – and over 2 billion do not have safe drinking water services. The United Nations predicts that by 2025, 1.8 billion people will be living in countries or regions with absolute water scarcity. With the existing climate change scenario, almost half the world’s population will be living in areas of high water stress by 2030. In addition, water scarcity in some arid and semi-arid places will displace between 24 million and 700 million people. By 2030, water scarcity could displace over 700 million people.
In Africa alone, as many as 25 African countries are expected to suffer from a greater combination of increased water scarcity and water stress by 2025. Sub-Saharan regions are experiencing the worst of the crisis, with only 22-34% of populations in at least eight sub-Saharan countries having access to safe water.
Water security, or reliable access to adequate quantities of acceptable quality water for health, livelihoods, ecosystems, and production has become an urgent issue worldwide.
This crisis has far-reaching implications for global health, food security, education, economics, and politics. As water resources dwindle, conflicts and humanitarian issues over access to clean water will likely increase. Climate change also exacerbates water scarcity in many parts of the world. Addressing this complex and multifaceted crisis requires understanding its causes, impacts, and potential solutions across countries and communities.
The global water crisis stems from a confluence of factors, including growing populations, increased water consumption, poor resource management, climate change, pollution, and lack of access due to poverty and inequality.
The world population has tripled over the last 70 years, leading to greater demand for finite freshwater resources. Agricultural, industrial, and domestic water usage have depleted groundwater in many regions faster than it can be replenished. Agriculture alone accounts for nearly 70% of global water withdrawals, often utilizing outdated irrigation systems and water-intensive crops.Climate change has significantly reduced renewable water resources in many parts of the world. Glaciers are melting, rainfall patterns have shifted, droughts and floods have intensified, and temperatures are on the rise, further exacerbating the crisis.
Baseline water stress measures the ratio of total water withdrawals to available renewable water supplies. Image: United Nations (2019).
In many less developed nations, lack of infrastructure, corruption, and inequality leave large populations without reliable access to clean water. Women and children often bear the burden of travelling distances to fetch water for households. Contamination from human waste, industrial activities, and agricultural runoff also threaten water quality and safety.
Water scarcity poses risks to health, sanitation, food production, energy generation, economic growth, and political stability worldwide. Conflicts over shared water resources are likely to intensify without concerted global action.
Case Study: Water Crisis in Gaza
The water crisis in Gaza represents one of the most severe cases of water scarcity worldwide. The small Palestinian territory relies almost entirely on the underlying coastal aquifer as its source of freshwater. However, years of excessive pumping far exceed natural recharge rates. According to the UN, 97% groundwater does not meet World Health Organization (WHO) standards for human consumption due to high salinity and nitrate levels.
The pollution of Gaza’s sole freshwater source stems from multiple factors. Rapid population growth contaminated agricultural runoff, inadequate wastewater treatment, and saltwater intrusion due to over-extraction have rendered the aquifer unusable.
In June 2007, following the military takeover of Gaza by Hamas, the Israeli authorities significantly intensified existing movement restrictions, virtually isolating the Gaza Strip from the rest of the occupied Palestinian territory (oPt), and the world. The blockade imposed by Israeli Authority also severely restricts infrastructure development and humanitarian aid.
The water crisis has devastated Gazan agriculture, caused widespread health issues, and crippled economic growth. Many citizens of Gaza have to buy trucked water of dubious quality, as the public network is unsafe and scarce. The United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) reports that this water can cost up to 20 times more than the public tariff, with some households spending a third of their income or more on water. Long-term solutions require increased water supplies, wastewater reuse, desalination, and better resource management under conflict.
According to a 2022 report by the WHO and UNICEF’s Joint Monitoring Programme (JMP), 344 million people in sub-Saharan Africa lacked access to safely managed drinking water, and 762 million lacked access to basic sanitation in 2020. WaterAid, a non-governmental organization, explains that water resources are often far from communities due to the expansive nature of the continent, though other factors such as climate change, population growth, poor governance, and lack of infrastructure also play a role. Surface waters such as lakes and rivers evaporate rapidly in the arid and semi-arid regions of Africa, which cover about 45% of the continent’s land area. Many communities rely on limited groundwater and community water points to meet their water needs, but groundwater is not always a reliable or sustainable source, as it can be depleted, contaminated, or inaccessible due to technical or financial constraints. A 2021 study by UNICEF estimated that women and girls in sub-Saharan Africa collectively spend about 37 billion hours a year collecting water, which is equivalent to more than 1 billion hours a day.The 2023 UN World Water Development Report emphasizes the importance of partnerships and cooperation for water, food, energy, health and climate security in Africa, a region with diverse water challenges and opportunities, low water withdrawals per capita, high vulnerability to climate change, and large investment gap for water supply and sanitation.
In the Meatu District in Shinyanga, an administrative region of Tanzania, water most often comes from open holes dug in the sand of dry riverbeds and it is invariably contaminated.
Water security in Africa is low and uneven, with various countries facing water scarcity, poor sanitation, and water-related disasters. Transboundary conflicts over shared rivers, such as the Nile, pose additional challenges for water management.
However, some efforts have been made to improve water security through various interventions, such as community-based initiatives, irrigation development, watershed rehabilitation, water reuse, desalination, and policy reforms. These interventions aim to enhance water availability, quality, efficiency, governance, and resilience in the face of climate change. Water security is essential for achieving sustainable development in Africa, as it affects numerous sectors, such as agriculture, health, energy, and the environment.
Other Countries with Water Shortages
Water scarcity issues plague many other parts of the world beyond Gaza and Africa. Several examples stand out:
Iraq faces severe water stress impacting agriculture and public health. The Tigris and Euphrates Rivers have dwindled because of upstream damming and climate change. Water distribution is inefficient and wasteful.
Indiagrapples with extensive groundwater depletion, shrinking reservoirs and glaciers, pollution from agriculture and industry, and tensions with Pakistan and China over shared rivers. Monsoons are increasingly erratic with climate change.
Projections show India will be under severe water stress by the end of the decade. Image: WRI.
While the specifics differ, recurrent themes include unsustainable usage, climate change, pollution, lack of infrastructure, mismanagement, poverty, transboundary conflicts, and population growth pressures. But resources often exist; the challenge lies in equitable distribution, cooperation, efficiency, and sustainable practices. Multiple approaches must accommodate local conditions and transboundary disputes.
Water scarcity poses a grave threat to global security on multiple fronts.
First, it can incite conflicts within and between nations over access rights. History contains many examples of water wars, and transboundary disputes increase the risk today in arid regions like the Middle East and North Africa.
Second, water shortages undermine food security. With agriculture consuming the greatest share of water resources, lack of irrigation threatens crops and livestock essential for sustenance and livelihoods. Food price spikes often trigger instability and migrations.
Third, water scarcity fuels public health crises, leading to social disruptions. Contaminated water spreads diseases like cholera and typhoid. Poor sanitation and hygiene due to water limitations also increase illness. The Covid-19 pandemic underscored the essential nature of water access for viral containment.
Finally, water shortages hamper economic growth and worsen poverty. Hydroelectricity, manufacturing, mining, and other water-intensive industries suffer. The World Bank estimates that by 2050, water scarcity could cost some regions 6% of gross domestic product (GDP), entrenching inequality. Climate migration strains nations. Overall, water crises destabilize societies on many levels if left unaddressed.
Solutions and Recommendations
Tackling the global water crisis requires both local and international initiatives across infrastructure, technology, governance, cooperation, education, and funding.
First, upgrading distribution systems, sewage treatment, dams, desalination, watershed restoration, and irrigation methods could improve supply reliability and quality while reducing waste. Community-based projects often succeed by empowering local stakeholders.
Second, emerging technologies like low-cost water quality sensors, affordable desalination, precision agriculture, and recyclable treatment materials could help poorer nations bridge infrastructure gaps. However, funding research and making innovations affordable remains a key obstacle.
Third, better governance through reduced corruption, privatization, metering, pricing incentives, and integrated policy frameworks could improve efficiency. But human rights must be protected by maintaining affordable minimum access.
Fourth, transboundary water-sharing treaties like those for the Nile and Mekong Rivers demonstrate that diplomacy can resolve potential conflicts. But political will is needed, along with climate change adaptation strategies.
Fifth, education and awareness can empower conservation at the individual level. Behaviour change takes time but can significantly reduce household and agricultural usage.
Finally, increased financial aid, public-private partnerships, better lending terms, and innovation prizes may help nations fund projects. Cost-benefit analyses consistently find high returns on water security investments.
In summary, sustainable solutions require combining new technologies, governance reforms, education, cooperation, and creative financing locally and globally.
Conclusion
The global water crisis threatens the well-being of billions of people and the stability of nations worldwide. Key drivers include unsustainable usage, climate change, pollution, lack of infrastructure, poverty, weak governance, and transboundary disputes. The multiple impacts span public health, food and energy security, economic growth, and geopolitical conflicts.
While daunting, this crisis also presents opportunities for innovation, cooperation, education, and holistic solutions. With wise policies and investments, water security can be achieved in most regions to support development and peace. But action must be accelerated on both global and community levels before the stresses become overwhelming. Ultimately, our shared human dependence on clean water demands that all stakeholders work in unison to create a water-secure future.
Climate change is exacerbating both water scarcity and water-related hazards (such as floods and droughts), as rising temperatures disrupt precipitation patterns and the entire water cycle.
Water and climate change are inextricably linked. Climate change affects the world’s water in complex ways. From unpredictable rainfall patterns to shrinking ice sheets, rising sea levels, floods and droughts – most impacts of climate change come down to water.
Climate change is exacerbating both water scarcity and water-related hazards (such as floods and droughts), as rising temperatures disrupt precipitation patterns and the entire water cycle.
Only 0.5 per cent of water on Earth is useable and available freshwater – and climate change is dangerously affecting that supply. Over the past twenty years, terrestrial water storage – including soil moisture, snow and ice – has dropped at a rate of 1 cm per year, with major ramifications for water security.
Melting glaciers, snow and permafrost are affecting humans and ecosystems in mid-to-high latitudes and the high-mountain regions. These changes are already impacting irrigation, hydropower, water supply, and populations depending on ice, snow and permafrost.
Climate change is one of the key drivers of the loss and degradation of freshwater ecosystems and the unprecedented decline and extinction of many freshwater-dependent populations, particularly due to land use and pollution.
Limiting global warming to 1.5°C compared to 2°C would approximately halve the proportion of the world population expected to suffer water scarcity, although there is considerable variability between regions.
Water quality is also affected by climate change, as higher water temperatures and more frequent floods and droughts are projected to exacerbate many forms of water pollution – from sediments to pathogens and pesticides.
Climate change, population growth and increasing water scarcity will put pressure on food supply as most of the freshwater used, about 70 per cent on average, is used for agriculture (it takes between 2000 and 5000 liters of water to produce a person’s daily food).
Rising global temperatures increase the moisture the atmosphere can hold, resulting in more storms and heavy rains, but paradoxically also more intense dry spells as more water evaporates from the land and global weather patterns change.
Annual mean precipitation is increasing in many regions worldwide and decreasing over a smaller area, particularly in the tropics.
Climate change has increased the likelihood of extreme precipitation events and the associated increase in the frequency and magnitude of river floods.
Climate change has also increased the likelihood or severity of drought events in many parts of the world, causing reduced agricultural yields, drinking water shortages, increased wildfire risk, loss of lives and economic damages.
Drought and flood risks, and associated societal damages, are projected to further increase with every degree of global warming.
Water-related disasters have dominated the list of disasters over the past 50 years and account for 70 per cent of all deaths related to natural disasters.
Since 2000, flood-related disasters have risen by 134 per cent compared with the two previous decades. Most of the flood-related deaths and economic losses were recorded in Asia. The number and duration of droughts also increased by 29 per cent over this same period. Most drought-related deaths occurred in Africa.
Water solutions
Healthy aquatic ecosystems and improved water management can lower greenhouse gas emissions and provide protection against climate hazards.
Wetlands such as mangroves, seagrasses, marshes and swamps are highly effective carbon sinks that absorb and store CO2, helping to reduce greenhouse gas emissions.
Wetlands also serve as a buffer against extreme weather events. They provide a natural shield against storm surges and absorb excess water and precipitation. Through the plants and microorganisms that they house, wetlands also provide water storage and purification.
Early warning systems for floods, droughts and other water-related hazards provide a more than tenfold return on investment and can significantly reduce disaster risk: a 24-hour warning of a coming storm can cut the ensuing damage by 30 per cent.
Water supply and sanitation systems that can withstand climate change could save the lives of more than 360,000 infants every year.
Even in countries with adequate water resources, water scarcity is not uncommon. Although this may be due to a number of factors — collapsed infrastructure and distribution systems, contamination, conflict, or poor management of water resources — it is clear that climate change, as well as human factors, are increasingly denying children their right to safe water and sanitation.
Water scarcity limits access to safe water for drinking and for practising basic hygiene at home, in schools and in health-care facilities. When water is scarce, sewage systems can fail and the threat of contracting diseases like cholera surges. Scarce water also becomes more expensive.
Water scarcity takes a greater toll on women and children because they are often the ones responsible for collecting it. When water is further away, it requires more time to collect, which often means less time at school. Particularly for girls, a shortage of water in schools impacts student enrolment, attendance and performance. Carrying water long distances is also an enormous physical burden and can expose children to safety risks and exploitation.
UNICEF/UNI315914/Haro Niger, 2020. Early in the morning, children go to the nearest water point to fetch water, 15 kilometres away from their home in Tchadi village.
Key facts
Four billion people — almost two thirds of the world’s population — experience severe water scarcity for at least one month each year.
Over two billion people live in countries where water supply is inadequate.
Half of the world’s population could be living in areas facing water scarcity by as early as 2025.
Some 700 million people could be displaced by intense water scarcity by 2030.
By 2040, roughly 1 in 4 children worldwide will be living in areas of extremely high water stress.
UNICEF’s response
As the factors driving water scarcity are complex and vary widely across countries and regions, UNICEF works at multiple levels to introduce context-specific technologies that increase access to safe water and address the impacts of water scarcity. We focus on:
Identifying new water resources: We assess the availability of water resources using various technologies, including remote sensing and geophysical surveys and field investigations.
Improving the efficiency of water resources: We rehabilitate urban water distribution networks and treatment systems to reduce water leakage and contamination, promoting wastewater reuse for agriculture to protect groundwater.
Planning for urban scarcity: We plan for future water needs by identifying available resources to reduce the risk of cities running out of water.
Expanding technologies to ensure climate resilience: We support and develop climate-resilient water sources, including the use of deeper groundwater reserves through solar-powered water networks. We also advance water storage through small-scale retention structures, managed aquifer recharge (where water is pumped into underground reserves to improve its quality), and rainwater harvesting.
Changing behaviours: We work with schools and communities to promote an understanding of the value of water and the importance of its protection, including by supporting environmental clubs in schools.
Planning national water needs: We work with key stakeholders at national and sub-national levels to understand the water requirements for domestic use and for health and sanitation, and advocate to ensure that this is reflected in national planning considerations.
Supporting the WASH sector: We develop technical guidance, manuals and online training programmes for WASH practitioners to improve standards for water access.
To mark World Water Week 2025, new report highlights persistent inequalities, with vulnerable communities left behind.
Despite progress over the last decade, billions of people around the world still lack access to essential water, sanitation, and hygiene services, putting them at risk of disease and deeper social exclusion.
A new report: Progress on Household Drinking Water and Sanitation 2000–2024: special focus on inequalities –launched by WHO and UNICEF during World Water Week 2025 – reveals that, while some progress has been made, major gaps persist. People living in low-income countries, fragile contexts, rural communities, children, and minority ethnic and indigenous groups face the greatest disparities.
Ten key facts from the report:
Despite gains since 2015, 1 in 4 – or 2.1 billion people globally – still lack access to safely managed drinking water*, including 106 million who drink directly from untreated surface sources.
3.4 billion people still lack safely managed sanitation, including 354 million who practice open defecation.
1.7 billion people still lack basic hygiene services at home, including 611 million without access to any facilities.
People in least developed countries are more than twice as likely as people in other countries to lack basic drinking water and sanitation services, and more than three times as likely to lack basic hygiene.
In fragile contexts**, safely managed drinking water coverage is 38 percentage points lower than in other countries, highlighting stark inequalities.
While there have been improvements for people living in rural areas, they still lag behind. Safely managed drinking water coverage rose from 50 per cent to 60 per cent between 2015 and 2024, and basic hygiene coverage from 52 per cent to 71 per cent. In contrast, drinking water and hygiene coverage in urban areas has stagnated.
Data from 70 countries show that while most women and adolescent girls have menstrual materials and a private place to change, many lack sufficient materials to change as often as needed.
Adolescent girls aged 15–19 are less likely than adult women to participate in activities during menstruation, such as school, work and social pastimes.
In most countries with available data, women and girls are primarily responsible for water collection, with many in sub-Saharan Africa and Central and Southern Asia spending more than 30 minutes per day collecting water.
As we approach the last five years of the Sustainable Development Goals period, achieving the 2030 targets for ending open defecation and universal access to basic water, sanitation and hygiene services will require acceleration, while universal coverage of safely managed services appears increasingly out of reach.
“Water, sanitation and hygiene are not privileges, they are basic human rights,” said Dr Ruediger Krech, Director a.i, Environment, Climate Change and Health, World Health Organization. “We must accelerate action, especially for the most marginalized communities, if we are to keep our promise to reach the Sustainable Development Goals.”
“When children lack access to safe water, sanitation, and hygiene, their health, education, and futures are put at risk,” said Cecilia Scharp, UNICEF Director of WASH. “These inequalities are especially stark for girls, who often bear the burden of water collection and face additional barriers during menstruation. At the current pace, the promise of safe water and sanitation for every child is slipping further from reach – reminding us that we must act faster and more boldly to reach those who need it most.”
This latest update – produced by WHO/UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene (JMP) – provides new national, regional and global estimates for water, sanitation and hygiene services in households from 2000 until 2024. The report also includes expanded data on menstrual health for 70 countries, revealing challenges that affect women and girls across all income levels.
The report is being launched during World Water Week 24-28 August 2025, the leading annual conference on global water issues, and bringing together stakeholders from across sectors to accelerate progress towards the Sustainable Development Goals.
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*JMP definition of ‘Safely managed drinking water and sanitation services’: Drinking water from sources located on premises, free from contamination and available when needed, and using hygienic toilets from which wastes are treated and disposed of safely.
**Fragile contexts: Fragility, according to the OECD, is the combination of exposure to risk and insufficient coping capacities of the state, system and/or communities to manage, absorb or mitigate those risks. It occurs in a spectrum of intensity across six dimensions: economic, environmental, human, political, security and societal.
About the JMP The WHO/UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene (JMP) was established in 1990 and has been tracking global progress for 35 years. It is responsible for monitoring Sustainable Development Goal targets 1.4, 6.1 and 6.2, which call for universal access to safe water, sanitation, hygiene and the elimination of open defecation by 2030.
A new report on the economic importance of a strong water sector forecasts that America will need to invest $3.4 trillion over the next 20 years to modernize its infrastructure.
As Iran’s water crisis continues, dams in the country’s second-largest city, Mashhad, have dwindled to less than 3 percent capacity.
Millions of people in Niger, Nigeria, and Ghana are at high risk of surface water contamination and loss as a result of deforestation, a new report indicates.
The over-extraction of sand from Cambodia’s Tonle Sap, Asia’s largest lake and a crucial Mekong River source, threatens to shrink its wet-season size by up to 40 percent.
The Lead
For every 1,000 hectares of forest cleared in Niger and Nigeria, almost 10 hectares of surface water disappear, according to a study released this month from Water Aid and Tree Aid, two international NGOs.
The links between deforestation and worsening water crises in West Africa are clear, the report shows. Across Ghana, Niger, and Nigeria, 122 million people live in areas of high surface water risk as a direct result of deforestation — a 5 million-person increase in five years. Nigeria alone, which loses 27,000 hectares of vegetation cover annually, accounts for 70 percent of this vulnerable population.
In Niger, the impacts of deforestation are particularly dire. Tree loss imperils nearly all the country’s available freshwater sources. In the primarily arid and semi-arid country, climate change is giving rise to a pronounced “more drought, more flood” phenomenon. Without forests to filter and absorb excess water, storms – when they do arrive – are falling increasingly in extreme bursts, resulting in runoff, contamination, and infrastructure damage. But there is also hope. Of the three countries studied, Niger is the only one to achieve a net gain in forest cover since 2013, adding more than 100,000 hectares.
When invested into water infrastructure in America, it yields $2.5 million in economic output, according to a report released last week by the nonprofit U.S. Water Alliance. What’s more, that $1 million provides 10 jobs, $837,000 in labor income, and $1.4 million in GDP.
The publication, a centerpiece of the organization’s Value of Water campaign, links the country’s financial health with sound water investments — a relationship that is strained by widespread underinvestment, it warns. Over the next 20 years, the report estimates that America will need to spend roughly $3.4 trillion to modernize and repair its aging wastewater, treatment, and stormwater facilities. The problem is comparatively worse in rural communities, which face greater needs per-capita than urban areas in 80 percent of states.
Per capita, these investments would have the greatest impact in North Dakota, Iowa, Louisiana, West Virginia, Vermont, and New Hampshire.
“Clean water utilities are on the frontlines of protecting public health and the environment. This report affirms what we have long known — that closing the investment gap will not only safeguard clean water, but also strengthen the entire U.S. economy,” Adam Krantz, CEO of the National Association of Clean Water Agencies, said in the report.
Amount by which the wet season-size of Tonle Sap, the largest lake in Asia, will shrink by 2038 if local mining continues at its current pace, according to a study published this week in the journal Nature Sustainability. A rising demand for sand, used to make concrete and glass, has led to increased dredging in the Cambodian lake, which drains for half of the year into the Mekong River, supporting its southern flow. But during the rainy summer months of May through October, rising water levels in the Mekong reverse this trend, and Tonle Sap pulses, “expanding the lake’s surface area by 4 to 6 times and swelling its water volume to 80 cubic kilometers,” Science reports. This dynamic supports some of the world’s most biodiverse riparian, lake, and wetland habitat, and the livelihoods and cultural identities of some 60 million people who live along the Mekong’s shores. In the absence of strong, nutrient-rich pulses, fisheries and water supplies are at risk of collapse.
According to Science, sand is the world’s second most-exploited resource, “often extracted from riverbeds or shores.” Water is the most exploited. Both Cambodia and Vietnam have banned sand export, though its mining from the Mekong watershed continues, to the detriment of its health and local human communities, flora, and fauna.
As the Tehran metropolitan area — home to nearly 18 million people — nears a potential Day Zero scenario within two weeks, Iran’s second-largest city is also facing acute water shortages amid widespread drought, exacerbated by mismanagement.
The water levels in dams in Mashhad, population 4 million, have dwindled to less than 3 percent capacity, Agence France-Presse (AFP) reports. The city’s water consumption has been measured at roughly 8,000 liters per second, “of which about 1,000 to 1,500 litres per second is supplied from the dams,” Hossein Esmaeilian, the chief executive of Mashhad’s water company, told AFP. Residents are urged to reduce their water consumption by 20 percent, he said.
Tehran officials admitted this week that water rationing began too late in the capital, a failure that may now lead to forced evacuations, according to Iran International. The country’s central plateau may be depopulated as a result of “a chronic disconnect between scientists, industry, and government agencies.” Already, residents of villages and rural regions have abandoned their land amid shortages and migrated toward city centers, further straining limited reservoir supplies.
Wetland Watch
MARSH Project: Near the historic downtown of Charleston, South Carolina, a grassroots effort to preserve important salt marshes along the Ashley River — installed amid rollbacks to the Clean Water Act — has proved successful in mitigating floods, the Associated Press reports.
On November 19, DC Water will launch an ambitious effort – Pure Water DC – to reduce the District’s reliance on the Potomac River as its only water source. We’ll be hosting an event to outline our vision and strategy for resilience and host an expert panel to address one of the most critical challenges facing the nation’s capital.
Any disruption to the Potomac or Washington Aqueduct—whether from contamination, drought, or infrastructure failure—would have catastrophic consequences for public health, the economy, and national security.
Pure Water DC seeks to mitigate that risk through a comprehensive program to strengthen water supply resilience and explore a second source of water for the District. This initiative represents a major investment and a regional call to action, inviting collaboration among utilities, agencies, and stakeholders to secure a drought-proof future.
EVENT DETAILS
What: Launch of Pure Water DC Program, unveiling the vision and strategy for water supply resilience, followed by an expert panel discussion.
When: Wednesday, November 19, 2025 10:00 a.m. – 12:00 p.m.
Where: DC Water Headquarters 1385 Canal Street SE Washington, DC 20003
Who: DC Water leadership, regional water utilities, environmental agencies, and federal partners including:
U.S. Environmental Protection Agency (EPA)
District Department of Energy & Environment (DOEE)
Water Environment Federation (WEF)
Interstate Commission on the Potomac River Basin (ICPRB)
WSSC Water
Greater Washington Board of Trade
Pure Water DC is DC Water’s commitment to lead the region toward a more resilient water future. The program will explore several options, including:
Safeguard our existing source and optimize the distribution system.
Add local storage and align with regional emergency storage efforts.
Explore advanced water reuse from Blue Plains as a drought-proof, cost-effective second source.
DC Water has committed $21 million over three years to fund studies, pilot projects, and public engagement, including the creation of the Pure Water DC Discovery Center at Blue Plains. This facility will test purification technologies, support regulatory research, and educate the public about water resilience.
The stakes are high: a major disruption could cost the region $15 billion in the first month alone.
Media should RSVP by Tuesday, November 18, at noon to Sherri Lewis at sherri.lewis@dcwater.com to attend and learn more about the new initiative, and next steps to create a more resilient water supply.
GET WET! 
