Water scarcity is the critical lack of fresh water resources needed to meet standard demand, manifesting in two primary forms. Physical water scarcity occurs when natural water resources are simply insufficient, common in arid regions like North Africa and Central Asia. In contrast, economic water scarcity arises from a lack of investment in infrastructure or capacity to access available water, a challenge faced by many in sub-Saharan Africa.

Globally, freshwater exists, but this crisis stems from a mismatch between when and where people need water and its availability, worsened by population growth, expanded agriculture, climate change, and pollution. This issue impacts billions: half a billion people endure severe water scarcity year-round, while around four billion experience it for at least one month annually, affecting half of the world's largest cities.

Addressing this widespread problem requires a multi-faceted approach, including better supply and demand management, international cooperation, water conservation efforts, and technological solutions like wastewater reuse and desalination to expand usable water sources.