Cooling
Cooling
Water use is a cooling choice, not a law of AI. Evaporative towers dump water to air. Closed-loop liquid cooling fills once and recirculates. Seawater and heat reuse are the other two exits. The existing fleet still mixes all of these.
Cooling
Evaporative
Water is sprayed or run over fill. Some evaporates. That is consumption. Alphabet, year ended 31 Dec 2025, EY-reviewed 22 Jun 2026: Council Bluffs consumed 1,346 million gallons. The Dalles consumed 469 million gallons. Same company, same year, cooling towers.
million gallons · Council Bluffs, 2025
million gallons · The Dalles, 2025
Schedule of Water Use by Data Center Location, year ended 31 Dec 2025
Cooling
Closed loop
Fill at construction. Water, or water and glycol, runs through the chips, hits a heat exchanger, and comes back. No evaporation in normal operation.
Microsoft, Steve Solomon, 9 Dec 2024: chip-level closed loop, zero water evaporated for cooling. More than 125 million liters avoided per datacenter per year, about 33 million gallons, is Microsoft's design estimate from FY2024 WUE, not a meter. Kitchens and restrooms still use water. New designs from Aug 2024. Phoenix and Mt. Pleasant are pilots and design, not live proof of zero-water cooling. Nominal extra electricity versus evaporative.
Microsoft Source, 23 Jun 2026: the first Mount Pleasant building is operational. That release does not say it runs the zero-water design.
New Microsoft sites using this design from late 2027.
Microsoft WUE 0.30 L/kWh last fiscal year, down from 0.49 in 2021, is the mixed fleet in that year, not the new closed-loop kit.
Meta, 2026: a majority of newest AI-optimized halls use closed-loop water and glycol. The coolant is expected to last up to a decade.
Amazon, AWS Summary for 2025, published July 2026: AWS global WUE 0.12 L/kWh, down 20% from 2024. Where weather permits, direct evaporative cooling uses water for less than 10% of the year. Configurable liquid-to-chip cooling is Amazon's line, without increasing water on a per-MW basis. IRHX is expected to cut water 9% versus evaporative air-cooled sites once fully operational. That 9% is an expectation, not a meter.
Cooling
Seawater and reuse
Alphabet's schedule excludes seawater returned to the sea. Hamina consumed 0.4 million gallons of freshwater in 2025.
Google and Haminan Energia, 20 May 2024: recovered heat into the town network, free except €1 + VAT. Haminan Energia said then it would cover 80% of annual district demand. That is a 2024 statement. There is no measured 2026 operating share on this page.
