Every product carries an invisible water footprint. A cotton t-shirt takes roughly 2,700 liters. A smartphone uses about 12,000 liters across mining, manufacturing, and assembly. When countries import goods, they effectively import the water used to make them.

Some nations export their water scarcity, growing thirsty crops for foreign markets while their own people face shortages. Pakistan exports cotton even as millions of Pakistanis lack clean drinking water at home — a sign that economics often moves water from scarce regions to abundant ones.