The Global Water Polycrisis

Food is the largest user. Agriculture accounts for 71% of the 3,850 cubic kilometres of fresh water withdrawn each year, and much of the irrigation that feeds Asia, the Middle East and the American west draws on groundwater faster than it recharges: across 1,693 aquifer systems with monitoring data, Jasechko and colleagues found water tables falling by more than 0.1 metres a year in 36% and by more than half a metre in 12%, with declines accelerating in 30%, concentrated in dry regions with extensive cropland. The Global Commission on the Economics of Water warned in 2024 that more than half of world food production is at risk by mid-century.

Energy is the second link. Thirty-nine countries generate half or more of their electricity from hydropower, eighteen of them in sub-Saharan Africa, and drought translates directly into blackouts. In 2024, Zambia — which gets around 84% of its electricity from hydropower — saw the Kariba reservoir fall to under a tenth of usable storage and imposed load-shedding of up to 21 hours a day. Thermal and nuclear plants need cooling water too, and they derate in hot, dry summers. Health is the third: unsafe water, sanitation and hygiene caused an estimated 1.4 million deaths in 2019, mostly of young children, through diarrhoea, respiratory infection and undernutrition.

Climate change runs through all of them, because it is felt mostly through water. Under a middle-of-the-road emissions path, CMIP6 models project that by 2040–2059 the average year will be as dry as a moderate drought used to be for 0.45 billion people in 18 countries, mostly in the Middle East and North Africa, while heavier downpours intensify across South Asia and West Africa. And development is where the costs land: the Commission estimates that the water crisis could cut median GDP by about 8% by 2050, and by 10–15% in lower-income countries. Sixty per cent of the world's fresh water flows across borders, shared by 153 countries.

The chart places each country by its water stress — the share of renewable fresh water withdrawn each year, the SDG 6.4.2 indicator — and by the share of its people without basic drinking water. Above 40% stress, the United Nations classes a country as under high stress; above 80% as critically stressed. Twenty-one countries withdraw 80% or more, from Kuwait, the United Arab Emirates and Saudi Arabia — which use many times their renewable supply, relying on fossil groundwater and desalination — to Egypt, Pakistan, Iran, Uzbekistan and Sri Lanka.

The striking pattern is how rarely the two axes coincide. The 35 physically scarce but served countries hold 4.1 billion people, including India, China, Pakistan, Mexico, Egypt and Iran; their population-weighted water stress averages 83%, agriculture takes 77% of their withdrawals, but only 4% of their people lack basic water. The 47 economically scarce countries hold 1.6 billion people, mostly in sub-Saharan Africa: their water stress averages just 14%, but 29% of people lack basic water, only 27% have safely managed water, and their rate of deaths from unsafe water — 42 per 100,000 — is six times that of served countries.

The correlations among the six exposure scores confirm the split. Water stress is negatively correlated with the food, health and capacity scores (−0.21 to −0.32) and with hydropower dependence (−0.42), but positively with projected drying (0.43). The food, health and capacity scores move together almost perfectly (0.87–0.92): they are three faces of underdevelopment. Only six countries, with 170 million people, are both stressed and lacking access — Sudan, Afghanistan, Yemen, Zimbabwe, Tajikistan and Eswatini — and they are among the most fragile states in the world.

Counting the exposures on which each country ranks in the top third gives a simple measure of stacking. Thirty-seven countries with 1.2 billion people are in the top third on none; 46 countries with 3.2 billion people, including China, on one; and 27 countries with 1.3 billion people on four or more. Sudan and Afghanistan rank in the top third on all six, and Ethiopia and Zimbabwe on five.

The four-plus group is overwhelmingly African — Nigeria, the DR Congo, Tanzania, Kenya, Uganda, Angola, Mozambique, Madagascar, Malawi, Zambia, Rwanda, Burundi, Guinea, Sierra Leone, Liberia, the Central African Republic, Mauritania and Lesotho — together with Afghanistan, Pakistan, Yemen, Tajikistan and Timor-Leste. Most stack food insecurity, deaths from unsafe water, dependence on hydropower and low capacity; the few that add water stress and projected drying are the fragile states of the double crisis.

Stacking matters because the exposures interact. A drought in a country that relies on rain-fed farming, hydropower and unprotected wells strikes harvests, electricity and health together, while the government that must respond has the least fiscal room. The table lets you sort the most exposed countries by any of the six scores; click a row to open its card in the atlas.

Physical scarcity is a problem of demand outrunning a fixed supply. In the 35 scarcity countries, agriculture takes 77% of withdrawals, and in the doubly exposed fragile states 93%. Much of that water now comes from aquifers that are not refilling: the rapid groundwater declines documented by Jasechko and colleagues are concentrated in dry, irrigated croplands — the Indus and Ganges plains, the North China Plain, Iran, the Arabian Peninsula, the American High Plains and Central Valley, and southern Spain. Groundwater is a buffer that lets farmers ride out drought; depleting it removes the buffer exactly as droughts intensify.

Climate change compounds the overuse. Among the scarcity countries, 30 with 0.9 billion people — including Mexico, Egypt, Iran, Türkiye, South Africa, Spain, Algeria, Iraq and Morocco — are projected to get drier by mid-century under SSP2-4.5. In 18 countries, mostly in the Middle East and North Africa, more than half the population is projected to live where the average year is as dry as a moderate drought in the reference climate. India and China are projected to get slightly wetter on average and Pakistan to change little, with heavier downpours in all three, but their dependence on groundwater and on rivers fed by Himalayan snow and ice — outside this local index — remains a central risk.

The good news is that water productivity is rising. The world now produces about $23 of GDP per cubic metre of water withdrawn, up from $14 in 2000 in constant dollars. But efficiency alone does not cure scarcity: more efficient irrigation often expands the irrigated area rather than reducing withdrawals, unless allocations are capped. Bangkok shows that recovery is possible — its groundwater levels rebounded after the government raised pumping fees.

Economic scarcity is a failure of infrastructure, utilities and finance rather than of supply. The WHO/UNICEF Joint Monitoring Programme counts 2.1 billion people without safely managed drinking water in 2024 and 3.4 billion without safely managed sanitation. Worldwide, the share with safely managed drinking water rose from 68% in 2015 to 74% in 2024, about two-thirds of a point a year; to reach everyone by 2030 would require more than six times that pace. Safely managed sanitation rose faster, from 48% to 59%, but would still need six times its recent pace.

The gap is widest in sub-Saharan Africa, where only 32% of people have safely managed drinking water and 26% safely managed sanitation. At the pace of the past decade, the region would reach near-universal safely managed water around 2123; reaching it by 2030 would require a pace 16 times faster. South Asia is the counter-example: its safely managed sanitation rose from 41% to 60% and basic sanitation from 57% to 82% between 2015 and 2024, on the back of India's sanitation campaign. The World Bank's region of the Middle East, North Africa, Afghanistan and Pakistan has stalled at about 65% safely managed water for a decade.

The health toll follows the access gap. Unsafe water, sanitation and hygiene caused an estimated 1.4 million deaths in 2019 — about 2.5% of all deaths — through diarrhoea, respiratory infections, undernutrition and intestinal worms. The age-standardised death rate is 41.5 per 100,000 in low-income countries, 34.6 in lower-middle-income, 6.0 in upper-middle-income and 3.7 in high-income countries; the highest rates are in Lesotho, Somalia, Chad, the Central African Republic, Nigeria and Niger. Because the same children who drink unsafe water are those most often undernourished, water and food insecurity reinforce each other.

Hydropower is low-carbon, cheap once built, and the backbone of electricity in much of Africa, South America and Central Asia. Thirty-nine countries with 1.1 billion people generate half or more of their electricity from it, eighteen of them in sub-Saharan Africa. That dependence is a water exposure: when rains fail, generation falls and, without alternatives, the lights go out. Since 2000, the largest single-year falls in hydropower generation among heavily dependent countries include Albania (45%, 2011), Zimbabwe (40%, 2016), Uganda (37%, 2006), Namibia (35%, 2021), Panama (35%, 2019) and Guinea (32%, 2003).

The 2024 southern African drought showed what this means. Zambia, which draws around 84% of its electricity from hydropower, imposed load-shedding of up to 21 hours a day as the Kariba reservoir fell below a tenth of its usable storage; Zimbabwe, which shares the dam, rationed too. Mines, factories, farms and households were all hit, and businesses turned to diesel generators. Ecuador, about three-quarters hydro, imposed blackouts of up to 14 hours a day in late 2024 as its worst drought in decades drained the reservoirs behind Mazar and the river feeding Coca Codo Sinclair.

Looking ahead, 18 of the 39 hydro-dependent countries are projected to get drier by mid-century under SSP2-4.5, including Zambia, Malawi, Mozambique, Zimbabwe, Namibia, Lesotho, Afghanistan, Tajikistan, Kyrgyzstan, Peru, Venezuela and Paraguay. The answer is not to abandon hydropower but to diversify around it: solar and wind, which peak in dry seasons when reservoirs are low; regional power pools that share surpluses; and reservoir operation that plans for drought rather than average years.

Warming intensifies the water cycle: warmer air holds more moisture, so wet extremes get wetter and evaporation dries the land between rains. CMIP6 projections, downscaled and bias-corrected to a quarter-degree grid by the World Bank, show the pattern clearly. By 2040–2059 under SSP2-4.5, drying is concentrated around the Mediterranean, the Middle East, southern Africa, Mexico and Central America and parts of South America, while the wettest five-day rainfall of the year rises by 7–12% across most of South Asia and by up to 16% in the Sahel.

That pattern maps onto the two crises unevenly. The physically scarce countries of the Middle East and North Africa face drying on top of overuse — the most acute physical squeeze anywhere. The economically scarce countries of West and East Africa face heavier downpours and floods, which overwhelm latrines, contaminate wells and wash out roads; while those of southern Africa face drought that hits hydropower and maize together. Higher emissions sharpen every signal: under SSP3-7.0, the population living in chronic drying in the countries most exposed rises further, and Morocco's share rises from 47% to 88%.

These are model medians, and the models disagree more about rainfall than about temperature. They also measure local conditions: for countries that depend on rivers rising elsewhere — Egypt on the Nile, Iraq on the Tigris and Euphrates, Pakistan and northern India on the Indus and Ganges — what happens upstream, and how upstream countries manage it, matters as much. Only 43 of the 153 countries that share rivers, lakes and aquifers have operational arrangements covering at least 90% of their transboundary waters.

The crisis-type layer shows the two crises side by side: physical scarcity from North Africa and the Arabian Peninsula through Iran and Central Asia to Pakistan, India and northern China, with outliers in Mexico, South Africa, Spain and the eastern Mediterranean; economic scarcity across sub-Saharan Africa and in parts of Asia and the Pacific; and the double crisis in Sudan, Yemen, Afghanistan, Tajikistan, Zimbabwe and Eswatini.

The stacking layer counts the exposures on which a country is in the top third; the remaining layers show the individual measures behind them. The hydropower layer highlights the Congo, Zambezi and Nile basins, the Andes and the Pamirs; the drying layer the Mediterranean and southern Africa; the WASH-mortality layer the Sahel and Central Africa.

Hover over a country to see its card: crisis type, water stress, renewable water per person, agriculture's share of withdrawals, access to safe and basic water and sanitation, deaths from unsafe water, undernourishment, hydropower share and worst recent hydro year, projected drying, and bars for all six exposures.

Where water is physically scarce, the priority is to bring use back within supply. That means capping and trading allocations so that efficiency gains are not simply used to irrigate more land; pricing and licensing groundwater pumping, as Bangkok did; shifting crops and diets towards less water-intensive production; treating and reusing wastewater, which is already the cheapest new water in many Middle Eastern cities; and desalination powered by cheap solar electricity for coastal cities. Transboundary agreements that share data and plan for drought are as important as any engineering.

Where water is economically scarce, the priority is investment and institutions. Reaching universal safely managed water and sanitation needs a six-fold acceleration globally and a sixteen-fold one in sub-Saharan Africa: utilities that can recover costs and borrow, rural service models that keep pumps working, sanitation that works in dense informal settlements, and climate-resilient designs that survive floods. Storage — from household tanks to small reservoirs and managed aquifer recharge — buffers rain-fed farming against erratic rains. The returns are large: safe water, sanitation and hygiene would save about 1.4 million lives a year.

For hydropower-dependent grids, the fix is diversification: solar and wind complement hydropower seasonally, and regional power pools let countries share surpluses, as the Southern African Power Pool is designed to do. Across all three, water must be governed as a system: food, energy and health ministries that plan with the same hydrology, finance that values water security as infrastructure, and data — monitoring of rivers, aquifers and services — that makes the coming squeeze visible before it arrives. In the fragile states where both crises meet, none of this is possible without stability.

Coverage: 160 countries with at least 1 million people. Water: SDG 6.4.2 level of water stress, total and sectoral freshwater withdrawals, renewable internal resources per person and water productivity (FAO AQUASTAT via World Bank WDI, latest to 2022). Access: safely managed and basic drinking water and sanitation (WHO/UNICEF JMP via WDI, 2000–2024); regional pace = 2015–2024 average annual change; required pace = gain to 99% by 2030. Health: age-standardised deaths attributable to unsafe WASH, 2019 (WHO via WDI). Food: prevalence of undernourishment and agricultural employment share (FAO, ILO via WDI). Energy: hydropower share of electricity, latest year, and the largest single-year fall in hydropower generation since 2000 for years with at least 0.5 TWh (Ember and the Energy Institute via Our World in Data).

Climate: World Bank CCKP CMIP6 0.25° bias-corrected ensemble medians for 1995–2014 and 2040–2059 under SSP2-4.5 and SSP3-7.0; country values are population-weighted (SSP2 population, 2050) means of the change in 20-year mean SPEI-12 and of the percentage change in annual maximum five-day precipitation, and the share of population where the 2040–2059 mean SPEI-12 is −1 or lower. Exposure scores: percentile ranks among the 160 countries — water = stress; food = mean of undernourishment and agricultural employment; energy = hydropower share; health = mean of WASH deaths and lack of basic water; climate = mean of projected drying and downpour intensification; capacity = inverse of GDP per head (PPP). High = top third (≥ 66.7). Crisis type: stressed = stress ≥ 40%; access gap = 10% or more without basic water.

Caveats: national stress hides basin-level stress and can exceed 100% where fossil groundwater or desalination is used; percentile scores are relative; SPEI is local and omits upstream inflows, snow and glaciers; WASH mortality is for 2019; hydropower falls can reflect commissioning or maintenance as well as drought; the six exposures are equally weighted and indicative. Related reports: Food, Energy, Water: Disruption and Substitution, The Global Climate–Pollution Risk Atlas and The Geography of Human Vulnerability Through 2100.