Water stress occurs when the demand for water exceeds the available supply during a certain period, or when poor quality restricts water use. It affects over two billion people worldwide.
Water stress is a condition in which the available freshwater resources in a region are insufficient to meet the demands of its population, economy, and ecosystems, either due to physical water scarcity, inadequate infrastructure, poor water quality, or institutional failures in water management. The Falkenmark Water Stress Indicator, one of the most widely used metrics, classifies regions as water-stressed when per capita renewable freshwater availability falls below 1,700 cubic meters per year, water-scarce below 1,000 cubic meters, and absolute water scarcity below 500 cubic meters. The World Resources Institute's Aqueduct Water Risk Atlas uses a ratio-based approach, defining baseline water stress as the ratio of total water withdrawals to available renewable supply, with ratios above 40 percent indicating high stress. Over 2 billion people currently live in countries experiencing high water stress, and this number is projected to increase significantly due to population growth, economic development, and climate change. Water stress manifests through symptoms including declining groundwater levels, reduced streamflows, degraded water quality, ecosystem deterioration, competition and conflict among users, and economic losses in water-dependent sectors. Addressing water stress requires demand management through conservation and efficiency improvements, supply augmentation through storage, reuse, and desalination, improved governance and allocation systems, and protection of watershed ecosystems that provide natural water purification and regulation services.