Focus on high and very high water risk areas.

 

Issues related to water represent the key ecological challenge facing humanity, as from them flow a host of resource scarcity concerns. The ETR’s water risk indicator is defined as the reliability of access to safe drinking water, combining two measures: the proportion of the population with access to clean water and the frequency of extreme monthly rainfall deficits compared with historical averages. This approach captures both long-term levels of water access and susceptibility to short-term fluctuations in water availability. Water stress emerges from both environmental and human factors. Ecological conditions limit water availability through factors such as insufficient rainfall, seasonal variability in rainfall, or the occurrence of floods and droughts. These factors restrict communities’ capacities to meet water demands for agriculture, households, and manufacturing industries. Human and economic pressures can also give rise to scarcity, often due to inadequate water management or infrastructure, despite water being potentially available. Examples include excessive groundwater extraction or outdated distribution systems, which billions of people depend on for freshwater. The 2025 ETR identifies 295 subnational areas with very high levels of water risk and a further 780 with high levels, encompassing nearly 1.9 billion people. In contrast, there are 811 subnational areas with very low water risk and 477 with low risk. In total, these latter two sets of areas are home to nearly 3.1 billion people.

Water risk is most severe in sub-Saharan Africa, South Asia, and South America, as shown in Figure 1.8. These regions account for more than 70 per cent of the global population facing high or very high levels of water risk, despite representing less than half (45 per cent) of the world’s population. As seen in Table 1.2, eight of the ten most threatened countries for the water risk indicator are in sub-Saharan Africa, with Guinea-Bissau recording the highest score globally.

Dependence on groundwater as a freshwater resource further compounds water uncertainty. Groundwater aquifers provide drinking water to more than two billion people worldwide, with approximately 70 per cent of withdrawals used for agriculture. However, over half of the world’s major aquifers (21 out of 37) are being depleted faster than they can naturally be replenished. Aquifers in South Asia and East Asia are among the most threatened. The five with the highest rates of over-extraction, where use exceeds natural recharge, are the Ganges, the Indus Basin, the California Central Valley Aquifer System, the North China Aquifer System, and the Tarim Basin in China. Around one billion people depend on these five aquifers for food and water, with the Indus Basin alone providing water for nearly 90 per cent of Pakistan’s food production. This has severe implications for vulnerable groups, particularly children. As of 2025, more than one-third of the global child population (over 920 million children) were highly exposed to water scarcity. This exposure undermines basic nutritional requirements, making children more vulnerable to severe diseases and impaired physical or cognitive development.

Five-Year Trends

 Changes in water risk scores over the past five years vary greatly across regions. As shown in Figure 1.9, South America, the Middle East and North Africa, and Eastern Europe and Central Asia experienced the greatest deteriorations. Western and Central Europe recorded the largest improvement in water risk, with its regional score falling by 0.374. This progress was primarily driven by an 82 per cent increase in the share of the population living within very low risk areas, which by 2024 encompassed more than three-quarters of the region’s inhabitants. Europe’s improvement reflects a recovery from its uncharacteristically high levels of water risk in 2019 (the baseline year of analysis). Around 2018-2020, the continent experienced prolonged droughts and record-breaking near-surface air temperatures, which greatly reduced water retention. By 2024, however, climatic conditions had returned closer to long-term norms, resulting in notable reductions in levels of water stress. All ten countries to record the largest improvements were European. These were led by Germany, Belgium, and the Netherlands. Moreover, the share of the global population exposed to high and very high water risk declined over the past five years, driven by modest improvements in highly populous areas stretching from northern India to Pakistan. Despite this, pressure on freshwater resources is projected to intensify in the coming decades. Population growth will drive higher demand and amplify global vulnerability. In 2024, the share of the population experiencing medium levels of water stress reached its highest level since 2020, highlighting the sensitivity of many communities to fluctuations in water availability. South America recorded the greatest deterioration between 2019 and 2024, as seen in Figure 1.9. The number of very low risk subnational areas fell sharply, from 59 in 2019 to just 22 in 2024. Simultaneously, the population living within very high risk zones rose by more than 9.8 million. While at the regional level South America showed the greatest deterioration in water risk, the individual countries to experience the largest increases in risk were all located in northwestern Africa. Tunisia experienced the greatest increase in water risk, which drove it to also register the largest deterioration in overall ETR score of any country. Algeria and Morocco respectively recorded the second and third largest increases in water risk.

 The substantial deteriorations in these three countries comes from a baseline of unusually favourable rainfall and evaporation conditions in 2019. That year, both Tunisia and Algeria had millions of inhabitants in very low risk areas. But last year these countries experienced prolonged droughts and especially high temperatures. As a result, all subnational areas in Tunisia were at medium risk levels last year, and the vast majority of Algeria’s populated areas – representing 86 per cent of the country’s total population – also recorded medium water risk scores. Similarly, Morocco faced severely increasing risks, with the population in very high risk areas rising by more than 24.3 million. 

Tunisia’s rise in risk has been exacerbated by the cumulative effects of deteriorating infrastructure. Chronic underinvestment and poor maintenance of pipe networks has led to extensive leakages, which depletes around 30 per cent of the country’s water supply before it reaches household taps. Last year’s droughts and temperature increases intensified these pressures, prompting governmentimposed restrictions, including water cut-offs that frequently exceeded ten hours.19 Last year, the Tunisian Water Observatory recorded over 2,100 unannounced water supply interruptions