4.2.11 (HL)—Water footprints

A water footprint estimates direct and indirect water used by a person, product, industry or nation, but volume alone is not impact.

Add where, when and what kind of water: rain, surface, groundwater and polluted return flows have different consequences. A litre in a wet basin is not equivalent to a litre in a dry-season basin.

Cotton’s irrigation footprint matters more in a stressed basin than the same volume of rainfall-supported production elsewhere.

A footprint becomes decision-relevant only when the place and season of withdrawal, competing human and ecosystem uses, and polluted return flows are attached to the volume.

A smaller footprint is not automatically safer if it shifts pollution or abstraction to another basin.