Amazon’s announcement arrives amid a politically charged debate over how much water and electricity data centers use. Some states and cities – including Amazon’s home base Seattle – have considered or implemented moratoriums on the construction of new server farms, in part to allow for further study.
Water researchers and community advocates say the only way to understand data center water usage is if Amazon and its peers share more granular data. Gradually, more information about water consumption is coming out.
After a protracted legal battle in Oregon, the city of The Dalles agreed to release records showing how much municipal water was being used by data centers operated by Alphabet Inc.’s Google. Utah recently passed a first-of-its-kind data center water transparency law that would require new data center developments of a certain size to disclose annual water withdrawals, among other metrics.
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“We need more transparency,” said Iris Stewart-Frey, a professor of environmental science at Santa Clara University and lead author of a report on California’s data center water usage. “Then communities will actually know what they’re getting into and can evaluate the costs and benefits, because the situation is very different from locality to locality.”
Among the largest cloud companies, only Google and Meta Platforms Inc. provide water usage data for individual facilities. It’s not clear if Amazon’s new disclosure will mollify critics. But Kerry Person, an Amazon Web Services vice president who oversees data center operations, said the company’s data is clear.
“If you look at the press right now, the data center industry is apparently consuming all of the water in the world,” he said in an interview. “When you actually look at the data and look at the details, nothing could be further from the truth.”
AWS data centers that use water for cooling chill their servers with air blown in from the surrounding environment. On days when temperatures exceed 85 degrees, that air is pushed through a water-soaked filter, cooling it on the way into data center halls and evaporating some of the water.
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Facilities in some regions where water is scarce — the Phoenix area and Saudi Arabia, for example — don’t rely on outside water sources for cooling, Amazon said, instead using air-cooled chillers that circulate refrigerant and water in closed loops.
Amazon’s water usage effectiveness calculation and its cumulative annual withdrawal figure include both water that is evaporated over the course of cooling the facility and liquid discharged to wastewater or other systems. Amazon’s Person said the company is trying to be conservative by including both measures. That makes it hard to make apples-to-apples comparison with other companies, which tend not to include discharged water.
Still, Amazon’s data suggests it’s a more efficient water user than its peers. The company said its facilities last year drew about 0.12 liters of water per kilowatt hour of electricity consumed, a metric designed to get at how efficiently a given data center uses water. That’s down from 0.15 liters per kilowatt hour in 2024, according to the company’s sustainability report.
Microsoft Corp.’s water usage effectiveness was 0.27 liters per kilowatt hour in the company’s most recently reported fiscal year. AWS, adjusting an academic estimate of data center use, pegged the industry average water withdrawal efficiency at 0.84 liters per kilowatt hour.
Amazon’s efficiency figure is based on sites that AWS owns or leases, excluding so-called colocation facilities where the company rents data center space, which in 2024 accounted for about a fifth of the computing power at Amazon’s disposal. The company’s disclosures also exclude water use required to generate the electricity that powers its data centers.
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Amazon has set a goal of returning more water to the environment and other users than it withdraws by 2030, by paying for projects including watershed restoration and refurbishment of wells and water systems. The company also currently pipes water to 26 of its own data centers, and is working on more than 100 more such water reclamation projects.
