Water scarcity

Water scarcity is a mismatch between water demand and water availability, quality, or accessibility. Physical scarcity occurs when renewable supplies cannot meet withdrawals and environmental needs; economic scarcity occurs when water exists but institutions, finance, infrastructure, or governance prevent people from obtaining it.¹ These conditions can coexist within one country or city.

Scarcity may be chronic, seasonal, or temporary. Drought is a climate episode, whereas scarcity describes the resulting or underlying relationship between supply and demand. Groundwater depletion can conceal scarcity for decades before wells fail, and polluted rivers can make nominally abundant water unusable. Common indicators include withdrawals relative to renewable supply, groundwater-level trends, household service reliability, and access to safe water rather than volume alone.³

Water scarcity is driven by rising demand, climate variability, pollution, ecosystem degradation, and poorly managed extraction. Agriculture accounts for roughly 70 percent of global freshwater withdrawals, while cities, industry, and energy systems create additional localized pressures.³ Population growth and changing diets can increase demand, but consumption and vulnerability are distributed unevenly.

Climate change intensifies many risks by altering precipitation, increasing evaporation, shrinking snow and ice stores, and making some droughts more severe or persistent; effects differ by region.⁵ Scarcity also crosses borders through trade in food, clothing, and industrial goods: imported products may embody water used in their production, a phenomenon studied as virtual water trade.⁴ Poor communities often face the greatest exposure despite contributing least to aggregate demand.

Water scarcity affects health, food production, livelihoods, ecosystems, and political stability. Unreliable supplies can increase the time spent collecting water, constrain hygiene, reduce crop yields, and encourage households or farmers to rely on unsafe sources. Excessive pumping causes land subsidence, seawater intrusion, and the loss of groundwater reserves that recover slowly or not at all.

Responses combine demand management with new or better-managed supply. They include reducing leakage, improving irrigation efficiency, reusing treated wastewater, protecting watersheds, restoring wetlands, harvesting rainwater, and regulating groundwater withdrawals. Desalination can supplement supplies in coastal areas but requires energy and produces concentrated brine. Effective policy also protects minimum flows for rivers and aquifers, prices or allocates water transparently, and prioritizes basic human needs. The United Nations Sustainable Development Goal 6 frames universal access, sustainable management, and water-quality protection as connected objectives.¹

Water scarcity is often hidden by infrastructure and unequal access rather than by an empty reservoir. A city may have a substantial bulk supply while informal settlements receive water intermittently or pay more per litre than connected households. Conversely, emergency scarcity can occur in a wet climate when floods contaminate treatment systems or damage distribution networks.

Groundwater creates another less visible dimension: aquifers can buffer drought, but their depletion is difficult to observe and may be masked by continued pumping. The water–energy nexus links scarcity to electricity because pumping, treatment, desalination, and water heating consume energy; energy production itself can require water for cooling.⁵ Agricultural efficiency does not automatically conserve water at basin scale if saved water expands irrigated area or shifts to thirstier crops. Accounting must therefore distinguish water withdrawn, consumed, returned, and reserved for ecosystems.⁴

Renewable freshwater

Surface water and groundwater replenished naturally over a specified period, chiefly through precipitation and recharge.

Physical water scarcity

A condition in which naturally available water is insufficient to satisfy human demand and ecological requirements.

Economic water scarcity

A condition in which water is available but access is limited by inadequate infrastructure, investment, institutions, or governance.

Virtual water

The water used to produce a traded good or service, considered as part of the product’s wider resource footprint.

Groundwater depletion

A sustained decline in stored groundwater caused when extraction exceeds recharge.