WUE (Water Usage Effectiveness)

WUE (Water Usage Effectiveness) measures data center water efficiency as liters of water consumed per kilowatt-hour of IT energy (L/kWh). It captures water lost to evaporative cooling towers, adiabatic systems, and humidification. Industry averages hover around 1.8 L/kWh, while facilities using air-cooled chillers or closed-loop liquid cooling can achieve WUE below 0.2 L/kWh; large evaporative-cooled sites in hot climates may exceed 2.5 L/kWh. WUE is standardized in ISO/IEC 30134-9 and has become a key siting and permitting metric as hyperscale campuses face scrutiny over local water supplies, especially in water-stressed regions like Arizona, Singapore, and parts of Southeast Asia. Operators increasingly publish WUE alongside PUE in sustainability disclosures.