Amazon published a 2025 water usage effectiveness figure of 0.12 liters of water per kilowatt-hour for its global data center fleet, a number it calls more than seven times better than the industry average of 0.84 L/kWh. About Amazon's coverage ties the figure to a 52% improvement in water efficiency since 2021 and reports that AWS withdrew about 2.5 billion gallons of water across its data centers last year. The post is a cooling architecture disclosure dressed as a sustainability update, and the architecture is the part worth reading closely.
Amazon attributes the 0.12 figure to free air cooling, which the company says runs roughly 90% of the time. The system pulls outside air across the servers to carry heat away, and only switches to evaporative cooling when ambient temperature climbs past about 85F. That leaves evaporative cooling handling something close to 10% of cooling hours. Raising the allowable operating temperature is what makes the air-side economizer viable for that large a share of the year, and it is the same lever the broader industry is pulling as it pushes toward warmer cooling loops that eliminate chillers.
The water savings come with an energy bill. Amazon notes that designing around chillers instead of evaporative cooling would require 25% to 35% more electricity. That is the central tradeoff in any water-versus-power conversation for cooling, and operators repeatedly land on the wrong side of it depending on local water cost, grid carbon, and drought exposure. We have written before about the water-power tradeoff operators keep getting wrong, and Amazon's framing is a clean statement of why the choice is rarely free.
Amazon says 26 facilities now run on 100% reclaimed water, with another 130 under contract globally. The company puts itself 75% of the way to a 2030 water-positive target, reporting that it returned roughly 3 gallons for every 4 it used in 2025 and that more than 50 water projects are expected to return over 5.8 billion gallons annually. Northern Virginia, one of the densest data center markets in the world, dropped water use 42% year over year by Amazon's account. Reclaimed and recycled supply is becoming a standard procurement move for hyperscale cooling, visible in deals like Amazon's reclaimed-water arrangement with Veolia in Mississippi.
The disclosure matters because WUE is now a competitive metric, and Amazon is publishing one low enough to set a benchmark rivals will be measured against. For cooling vendors, the message is that air-side economization plus high-temperature operation remains the cheapest path to a low water footprint at air-cooled rack densities. The unresolved question is what happens as rack power climbs into the range where air cooling stops working and liquid loops become mandatory. Direct-to-chip and immersion systems change the water and energy accounting entirely, and a 0.12 L/kWh figure built on outside air will not survive a fleet-wide shift to liquid without a new set of numbers behind it.