- Water scarcity happens when communities can’t fulfill their water needs, either because supplies are insufficient or infrastructure is inadequate. Today, billions of people face some form of water stress.
- Countries have often cooperated on water management. Still, there are a handful of places where transboundary waters are driving tensions, such as the Nile Basin.
- Climate change will likely exacerbate water stress worldwide, as rising temperatures lead to more unpredictable weather and extreme weather events, including floods and droughts.
Billions of people around the world lack adequate access to one of the essential elements of life: clean water. Although governments and aid groups have helped many living in water-stressed regions gain access in recent years, the problem is projected to get worse due to global warming and population growth.
Water stress can differ dramatically from one place to another, in some cases causing wide-reaching damage, including to public health, economic development, and global trade. It can also drive mass migrations and spark conflict. Now, pressure is mounting on countries to implement more sustainable and innovative practices and to improve international cooperation on water management.
What is water stress?
Water stress or scarcity occurs when demand for safe, usable water in a given area exceeds the supply. On the demand side, the vast majority—roughly 70 percent—of the world’s freshwater is used for agriculture, while the rest is divided between industrial (19 percent) and domestic uses (11 percent), including for drinking. On the supply side, sources include surface waters, such as rivers, lakes, and reservoirs, as well as groundwater, accessed through aquifers.
But scientists have different ways of defining and measuring water stress, taking into account a variety of factors including seasonal changes, water quality, and accessibility. Meanwhile, measurements of water stress can be imprecise, particularly in the case of groundwater. “Any numbers out there have to be taken with a grain of salt,” says Upmanu Lall, a Columbia University professor and water expert. “None of these definitions are typically accounting for groundwater usage, or groundwater stock.”
What causes water scarcity?
Water scarcity is often divided into two categories: physical scarcity, when there is a shortage of water because of local ecological conditions; and economic scarcity, when there is inadequate water infrastructure.
The two frequently come together to cause water stress. For instance, a stressed area can have both a shortage of rainfall as well as a lack of adequate water storage and sanitation facilities. Experts say that even when there are significant natural causes for a region’s water stress, human factors are often central to the problem, particularly with regard to access to clean water and safe sanitation. Most recently, for example, the war in Ukraine damaged critical infrastructure, leaving six million people with limited or no access to safe water in 2022.
“Almost always the drinking water problem has nothing to do with physical water scarcity,” says Georgetown University’s Mark Giordano, an expert on water management. “It has to do with the scarcity of financial and political wherewithal to put in the infrastructure to get people clean water. It’s separate.”
At the same time, some areas that suffer physical water scarcity have the infrastructure that has allowed life there to thrive, such as in Oman and the southwestern United States.
A variety of authorities, from the national level down to local jurisdictions, govern or otherwise influence the water supply. In the United States, more than half a dozen federal agencies deal with different aspects of water: the Environmental Protection Agency (EPA) enforces regulations on clean water, while the Federal Emergency Management Agency (FEMA) prepares for and responds to water disasters. Similar authorities exist at the state and local levels to protect and oversee the use of water resources, including through zoning and rehabilitation projects.
Which regions are most water-stressed?
The Middle East and North Africa (MENA) is the worst off in terms of physical water stress, according to most experts. MENA receives less rainfall than other regions, and its countries tend to have fast-growing, densely populated urban centers that require more water. But many countries in these regions, especially wealthier ones, still meet their water needs. For example, the United Arab Emirates (UAE) imports nearly all of its food, alleviating the need to use water for agriculture. The UAE and other wealthy MENA countries also rely heavily on the desalination of abundant ocean water, albeit this process is an expensive, energy-intensive one.
Meanwhile, places experiencing significant economic scarcity include Central African countries such as the Democratic Republic of Congo, which receives a lot of rain but lacks proper infrastructure and suffers from high levels of mismanagement.
Even high-income countries experience water stress. Factors including outdated infrastructure and rapid population growth have put tremendous stress on some U.S. water systems, causing crises in cities including Flint, Michigan, and Newark, New Jersey.
How is climate change affecting water stress?
For every 1°C (1.8°F) increase in the global average temperature, UN experts project a 20 percent drop in renewable water resources. Global warming is expected to increase the number of water-stressed areas and heighten water stress in already affected regions. Subtropical areas, such as Australia, the southern United States, and North African countries, are expected to warm and suffer more frequent and longer droughts; however, when rainfall does occur in these regions, it is projected to be more intense. Weather in tropical regions will likewise become more variable, climate scientists say.
Agriculture could become a particular challenge. Farming suffers as rainfall becomes more unpredictable and rising temperatures accelerate the evaporation of water from soil. A more erratic climate is also expected to bring more floods, which can wipe out crops an overwhelm storage systems. Furthermore, rainfall runoff can sweep up sediment that can clog treatment facilities and contaminate other water sources.
In a 2018 report, a panel consisting of many of the world’s top climate researchers showed that limiting global warming to a maximum 1.5°C (2.7°F) above preindustrial levels—the aim of the Paris Agreement on climate—could substantially reduce the likelihood of water stress in some regions, such as the Mediterranean and southern Africa, compared to an unchecked increase in temperature. However, most experts say the Paris accord will not be enough to prevent the most devastating effects of climate change.
What are its impacts on public health and development?
Prolonged water stress can have devastating effects on public health and economic development. More than two billion people worldwide lack access to safe drinking water; and nearly double that number—more than half the world’s population—are without adequate sanitation services. These deprivations can spur the transmission of diseases such as cholera, typhoid, polio, hepatitis A, and diarrhea.
At the same time, because water scarcity makes agriculture much more difficult, it threatens a community’s access to food. Food-insecure communities can face both acute and chronic hunger, where children are more at risk of conditions stemming from malnutrition, such as stunting and wasting, and chronic illnesses due to poor diet, such as diabetes.
Even if a water-stressed community has stable access to potable water, people can travel great lengths or wait in long lines to get it—time that could otherwise be spent at work or at school. Economists note these all combine [PDF] to take a heavy toll on productivity and development.
The COVID-19 pandemic heightened the need for safe water access. Handwashing is one of the most effective tools for combating the coronavirus, but health experts noted that three in ten individuals—2.3 billion people globally—could not wash their hands at home at the pandemic’s onset.
How has water factored into international relations?
Many freshwater sources transcend international borders, and, for the most part, national governments have been able to manage these resources cooperatively. Roughly three hundred international water agreements have been signed since 1948. Finland and Russia, for example, have long cooperated on water-management challenges, including floods, fisheries, and pollution. Water-sharing agreements have even persisted through cross-border conflicts about other issues, as has been the case with South Asia’s Indus River and the Jordan River in the Middle East.
However, there are a handful of hot spots where transboundary waters are a source of tension, either because there is no agreement in place or an existing water regime is disputed. One of these is the Nile Basin, where the White and Blue Nile Rivers flow from lakes in East Africa northward to the Mediterranean Sea. Egypt claims the rights to most of the Nile’s water based on several treaties, the first dating back to the colonial era; but other riparian states say they are not bound to the accords because they were never party to them. The dispute has flared in recent years after Ethiopia began construction of a massive hydroelectric dam that Egypt says drastically cuts its share of water.
Transboundary water disputes can also fuel intrastate conflict; some observers note this has increased in recent years, particularly in the hot spots where there are fears of cross-border conflict. For example, a new hydropower project could benefit elites but do little to improve the well-being of the communities who rely on those resources.
Moreover, water stress can affect global flows of goods and people. For instance, wildfires and drought in 2010 wiped out Russian crops, which resulted in a spike in commodities prices and food riots in Egypt and Tunisia at the start of the Arab uprisings. Climate stress is also pushing some to migrate across borders. The United Nations predicts that without interventions in climate change, water scarcity in arid and semi-arid regions will displace hundreds of millions of people by 2030.
What are international organizations and governments doing to alleviate water stress?
There has been some international mobilization around water security. Ensuring the availability and sustainable management of water and sanitation for all is one of the UN Sustainable Development Goals (SDGs), a sweeping fifteen-year development agenda adopted by member states in 2015. Smart water management is also vital to many of the other SDGs, such as eliminating hunger and ensuring good health and well-being. And while the Paris Agreement on climate does not refer to water explicitly, the United Nations calls [PDF] water management an “essential component of nearly all the mitigation and adaptation strategies.” The organization warns of the increasing vulnerability of conventional water infrastructure, and points to many climate-focused alternatives, such as coastal reservoirs and solar-powered water systems.
Governments and partner organizations have made progress in increasing access to water services: Between 2000 and 2017, the number of people using safely managed drinking water and safely managed sanitation services rose by 10 percent and 17 percent, respectively. In 2022, the Joe Biden administration announced an action plan to elevate global water security as a critical component of its efforts to achieve U.S. foreign policy objectives. But the pace of climate change and the COVID-19 pandemic have presented new challenges. Now, many countries say they are unlikely to implement integrated water management systems by 2030, the target date for fulfilling the SDGs.
Still, some governments are taking ambitious and creative steps to improve their water security that could serve as models for others:
Green infrastructure. Peruvian law mandates that water utilities reinvest a portion of their profits into green infrastructure (the use of plant, soil, and other natural systems to manage stormwater), and Canada and the United States have provided tens of millions of dollars in recent years to support Peru’s efforts [PDF]. Vietnam has taken similar steps to integrate natural and more traditional built water infrastructure.
Wastewater recycling. More and more cities around the globe are recycling sewage water into drinking water, something Namibia’s desert capital has been doing for decades. Facilities in countries including China and the United States turn byproducts from wastewater treatment into fertilizer.
Smarter agriculture. Innovations in areas such as artificial intelligence and genome editing are also driving progress. China has become a world leader in bioengineering crops to make them more productive and resilient.
The Wilson Center’s Lauren Risi writes that water wars between countries have not come to pass, but subnational conflicts over the resource are already taking a toll.
CFR’s Why It Matters podcast talks to Georgetown University’s Mark Giordano and the Global Water Policy Project’s Sandra Postel about water scarcity.
The World Resources Institute’s Aqueduct maps the areas facing extremely high water stress.
The United Nations shares facts about water and its role in all aspects of life.
BuzzFeed News interviews residents of Jackson, Mississippi, who lost access to safe water after freezing temperatures wreaked havoc on the city’s decaying infrastructure.
Emily Lieberman contributed to this Backgrounder. Michael Bricknell and Will Merrow helped create the graphics.