Half of the world’s largest cities are experiencing severe water stress, with nearly 40 of them classified in regions facing extreme shortages. Beijing, New York, Los Angeles, Rio de Janeiro, and Delhi are among the worst affected.
Water stress occurs when withdrawals for public supply and industry approach the limits of available resources. Experts say poor urban water management and climate impacts on cities are key drivers.
Analysis using satellite data shows which cities have been drying or becoming wetter over the past two decades. Chennai, Tehran, and Zhengzhou are drying rapidly, while Tokyo, Lagos, and Kampala show significant wetting trends over time.
Approximately 1.1 billion people live in cities in regions experiencing long-term drying. By contrast, only around 96 million live in areas showing consistent wetting, demonstrating stark global inequalities in water availability.
Most drying zones are concentrated across northern India and Pakistan, where demand has grown rapidly with urban expansion. Wetting zones are largely concentrated in sub-Saharan Africa, where rainfall patterns have shifted in recent decades.
Tehran is approaching a “day zero” scenario, when its water supply could run out completely. Authorities have warned that if the drought continues, evacuation of residents may become necessary to prevent humanitarian crises.
Cape Town and Chennai have previously faced near shortages. Many of the world’s fastest-growing cities are located in drying zones, heightening the risk of future water shortages and long-term urban water insecurity.
Experts warn that poor management, rather than climate change alone, is often the main cause of water stress. Inefficient water systems, leaks, and lack of monitoring exacerbate pressures on urban supplies globally.
Global freshwater reserves have plunged sharply over the past 20 years, affecting major river basins on every continent. Scientists estimate losses equivalent to the annual needs of more than 280 million people.
Urban water management is increasingly critical as populations grow. Cities must invest in monitoring, infrastructure, and sustainable water use policies to maintain supplies and reduce the risk of crisis.
In England, rising demand is projected to require an additional five billion litres of water per day by 2055. Southern regions have already experienced temporary outages, highlighting vulnerabilities in local water systems.
Groundwater offers a hidden but crucial resource for cities facing shortages. Experts stress the need for long-term monitoring and management to make this resource sustainable amid development pressures and climate change.
Satellite data provides early warning signs of emerging water insecurity, helping planners identify regions at risk and prioritize interventions before day-zero scenarios occur.
Some of the largest cities, including London, Bangkok, and Jakarta, face high water stress despite not being in extreme drying zones. Population growth and industrial demand drive pressures on water infrastructure in these areas.
The United Nations has warned that the world has entered a state of water bankruptcy, where deterioration of some water resources has become permanent and irreversible. Poor management is cited as the most frequent cause.
Water shortages are expected to intensify in rapidly urbanizing regions. Cities in Asia and the Middle East face some of the greatest long-term risks, while sub-Saharan Africa’s wetting zones may still experience localized shortages.
The World Bank reports that global freshwater losses amount to 324 billion cubic meters per year, enough to meet the annual needs of hundreds of millions of people.
These losses affect agriculture, energy, and municipal water sectors alike.
Many experts describe climate change as a compounding factor rather than a primary driver.
Management failures, over-extraction, and inefficient infrastructure magnify the impacts of altered rainfall and drought cycles.
Urban water management reforms are underway in several countries. Plans include better regulation, infrastructure maintenance, groundwater management, and the creation of new oversight bodies to monitor supply and demand.
In England, regulators are urging improvements in water resilience. Winter storms have exposed vulnerabilities, causing outages that highlight the need for comprehensive planning and sustained investment in water infrastructure.
The hidden potential of groundwater as a climate-resilient supply source remains largely untapped. Proper monitoring and sustainable management could prevent many urban water shortages in the coming decades.
Satellite-based monitoring helps identify drying and wetting trends in major urban centers, providing critical data to prevent crises. This technology allows early interventions and strategic allocation of water resources.
Population growth continues to drive demand in many water-stressed cities. Rapid urban expansion in northern India, Pakistan, and parts of Africa is straining existing water systems, requiring urgent policy and infrastructure responses.
Without sustained monitoring and management, cities risk increasingly frequent shortages. Experts stress the importance of efficient urban water management, better infrastructure, and proactive planning to mitigate long-term risks.
Climate impacts on cities, including heatwaves, droughts, and shifting rainfall patterns, further strain water systems. Policymakers must consider both environmental and human factors in developing solutions.
Some cities may face day-zero scenarios within a decade if current trends continue. Early warning systems and comprehensive planning are essential to prevent humanitarian and economic crises.
Global freshwater reserves are declining, and urgent action is needed to protect water security. International cooperation, improved urban water management, and investment in infrastructure are critical for sustainable city development.
Authorities emphasize that water shortages are not inevitable. Strategic planning, investment, and sustainable resource management can ensure that the world’s largest cities maintain adequate water supplies for growing populations.
