Freshwater scarcity is the imbalance between the demand for clean water and its available supply. It is categorized into two types: physical scarcity and economic scarcity. Physical scarcity occurs when there are insufficient water resources to meet demands, often in arid climates. Economic scarcity happens when water is physically present but inaccessible due to a lack of infrastructure or financial capacity to distribute it. Although only about 0.5% of the Earth’s water is usable freshwater, its limited supply is threatened by natural constraints and human activities.
Climate and Geographic Constraints
The distribution of freshwater is naturally uneven across the globe, creating regional scarcity even when global supply is adequate. Regions like Central Asia, West Asia, and North Africa are inherently prone to physical water scarcity due to their arid and semi-arid climates. This natural imbalance is intensified by global climate changes that disrupt the water cycle.
Rising global temperatures increase evaporation, depleting surface water levels in reservoirs and lakes. Warming also alters precipitation patterns, causing intense rainfall and flooding in some areas while others suffer from prolonged drought. Many communities rely on glaciers and snowpacks as natural reservoirs that release water gradually. Accelerated melting initially increases river flow but will lead to a sharp decline in water supply as these sources diminish.
Unsustainable Sectoral Consumption
The volume of water withdrawn for human use places a substantial strain on renewable freshwater resources. Global demand has been steadily increasing, driven largely by population growth, economic development, and increasing consumption. This excessive demand across multiple sectors is a primary driver of scarcity.
Agriculture is the largest consumer of freshwater, accounting for approximately 70% of global withdrawals, primarily for irrigation. In low-income countries, this percentage can reach 90%, creating immense pressure on local water tables and rivers. The need to feed a growing global population necessitates increased agricultural production, leading to a projected increase in water withdrawals.
Industrial processes and energy production are the second-largest consumers, accounting for about 19% of global freshwater withdrawals. This includes water for manufacturing, processing, and cooling in power generation plants. Municipal and domestic use accounts for the remaining 12% of global withdrawals. Poorly maintained infrastructure also contributes significantly, leading to massive losses of treated water due to leaks, known as “non-revenue water.”
Reliance on groundwater for irrigation and domestic purposes has led to the over-extraction of underground reserves. Currently, one-third of the world’s largest aquifer systems are under stress. When extraction exceeds the natural recharge rate, it depletes the aquifer, threatening future water supplies. This unsustainable consumption rate is rapidly depleting the accessible freshwater supply.
Water Quality Degradation
Even where physical volumes of water exist, contamination can render the supply unusable, effectively reducing available freshwater. Pollution from human activities introduces various contaminants into rivers, lakes, and aquifers. This degradation transforms a volume problem into a quality problem, exacerbating scarcity.
Agricultural runoff is a major source of contamination, carrying pesticides, herbicides, and excess fertilizers into water bodies. These nutrients trigger eutrophication, leading to excessive algae growth and subsequent oxygen depletion that harms aquatic life. Industrial discharge introduces heavy metals, chemical toxins, and inadequately treated wastewater into the environment.
Municipal sources also degrade water quality, as more than 80% of the world’s wastewater flows back into the environment without sufficient treatment. This untreated sewage introduces pathogens, bacteria, and viruses, making the water unsafe for consumption and promoting the spread of waterborne diseases. In coastal areas, over-extraction of groundwater lowers the water table, reducing the pressure that keeps saltwater at bay. This pressure imbalance allows denser saltwater to intrude laterally into freshwater aquifers, a process known as saltwater intrusion, which contaminates both drinking and irrigation supplies.