Water shortages are not a future hypothetical. Roughly half the world’s population already experiences severe water scarcity for at least part of the year, and the problem is getting worse. The number of urban residents facing water scarcity is projected to more than double by 2050, reaching up to 2.4 billion people. Whether you live in a major Western city or a rural community in South Asia, the trajectory points toward tighter supplies, higher costs, and more frequent crises.
Where Water Shortages Already Exist
Several major cities have already come dangerously close to running completely dry. Cape Town, South Africa, famously began counting down to “Day Zero” in 2017 after three years of drought, the point at which taps would be shut off and residents would collect daily rations from public distribution points. São Paulo, Brazil, saw its reservoirs drop to just 5% of capacity during a severe drought between 2013 and 2015, forcing utilities to reduce water pressure across the city. Melbourne, Las Vegas, and New Orleans have all faced serious shortages requiring restrictions.
These aren’t isolated events in water-poor countries. In late 2024, parts of the northeastern United States experienced moderate to severe drought. New York City and Boston asked residents to cut back, while Philadelphia faced the unusual threat of saltwater pushing up the Delaware River and contaminating its freshwater supply. Water stress can emerge almost anywhere when drought, infrastructure limits, and high demand converge.
Why Supply Is Shrinking
Two forces are draining the planet’s freshwater reserves simultaneously: climate change is reducing surface water, and overuse is depleting what lies underground.
Glaciers function as the planet’s largest natural freshwater reservoirs, holding nearly two-thirds of the world’s fresh water. Approximately half of them are projected to disappear by 2100, even if global warming stays at 1.5°C. In most major river basins fed by mountain ice, glacier area and volume will shrink by more than 40%. Smaller glaciers may lose up to 90%. For the roughly 2 billion people in Asia, South America, and other regions who depend on glacier-fed rivers for drinking water and irrigation, this is an existential shift. Peak runoff from melting glaciers is expected around 2050 under optimistic climate scenarios, meaning rivers will swell temporarily before declining permanently.
Underground, the picture is equally concerning. A sweeping analysis of 170,000 monitoring wells across 1,693 aquifer systems found that rapid groundwater declines, defined as levels dropping more than half a meter per year, are widespread in the 21st century. This is especially true in dry regions with extensive farmland. In 30% of the world’s regional aquifers, the rate of decline has accelerated, with early 21st-century drops outpacing those of the late 20th century. Among aquifers that were already losing water, the ratio of those getting worse to those improving was 5 to 2. Groundwater doesn’t refill quickly. Many of these aquifers took thousands of years to accumulate their reserves.
Agriculture Is the Biggest Driver
Farming accounts for roughly 70% of all freshwater withdrawals globally, dwarfing both industrial and household use. Growing food is inherently water-intensive: producing a single kilogram of beef can require over 15,000 liters, and even rice needs around 2,500 liters per kilogram. As the global population grows toward 9 to 10 billion by mid-century, agricultural demand will rise further unless efficiency improves dramatically.
Domestic water use, by comparison, is a smaller slice of the problem, but it still matters. The World Health Organization sets the minimum at about 20 liters per person per day for basic health and hygiene. Bare survival, covering drinking, cooking, and minimal washing, requires 7.5 to 15 liters daily. Billions of people currently use far more than this, while hundreds of millions struggle to secure even the minimum.
What Happens When Water Runs Short
Water scarcity isn’t just an inconvenience. It creates a cascade of health risks. When people can’t wash their hands regularly, respiratory and gastrointestinal illnesses spread more easily. Drought concentrates pollutants in rivers and streams, and bacteria like E. coli and Salmonella contaminate food more readily when crops are irrigated with improperly treated water. Warm, shallow water left behind by low river levels encourages the growth of dangerous organisms, including brain-eating amoebas. Recreational water becomes riskier. Heavy metals and chemical contaminants become more concentrated.
The economic consequences ripple outward from there. Crop failures raise food prices. Energy production falters when hydroelectric dams and cooling systems lack sufficient water. Property values drop in regions where water reliability becomes uncertain. Cities that come close to Day Zero often see businesses relocate.
Can Technology Close the Gap?
Desalination, the process of removing salt from seawater, is the most discussed technological fix. Modern reverse osmosis systems push saltwater through a membrane at high pressure, producing fresh water at a cost of $0.50 to $2.50 per cubic meter. That’s 1.5 to 4 times more expensive than drawing water from rivers or wells, which typically costs $0.10 to $1.00 per cubic meter. Older thermal desalination methods, which boil and condense seawater, consume roughly 5 to 15 kilowatt-hours per cubic meter. Reverse osmosis has brought that down to about 2 to 4 kilowatt-hours for a full installation.
Wastewater recycling is another option, costing $0.30 to $1.15 per cubic meter, making it competitive with or cheaper than desalination. Cities like Singapore, Orange County in California, and Windhoek in Namibia already treat and reuse wastewater for drinking. These technologies work, but they require massive energy inputs and capital investment, putting them out of reach for many of the regions where water stress is most acute.
What the Next Few Decades Look Like
The UN projects that the global urban population facing water scarcity will grow from 930 million in 2016 to between 1.7 and 2.4 billion by 2050. That growth is driven by three converging forces: population increase concentrated in water-stressed regions, rising temperatures that alter rainfall patterns and accelerate evaporation, and continued overextraction of groundwater that cannot be replaced on human timescales.
Cities that have already faced near-catastrophic shortages offer a partial roadmap. Cape Town cut daily per-person water use dramatically through a combination of pressure reduction, tiered pricing, and public campaigns. Las Vegas invested heavily in recycling every drop of indoor water that reaches its treatment plant. São Paulo reduced system pressure to physically limit how much water residents could draw. These strategies bought time, but none of them solved the underlying supply problem.
The honest answer is that water shortages are not coming. They are here, they are expanding, and the regions affected will grow substantially over the next 25 years. The severity you personally face depends on where you live, how your local government manages supply, and how quickly agricultural and industrial practices adapt to a world with less available fresh water than the one previous generations inherited.