Earlier this year, e-commerce giant Amazon received approval to open two new data centers in Santiago, Chile. The $400 million project is the company’s first attempt to locate its data centers, which use vast amounts of electricity and water to run cloud computing services and online programs, in Latin America – one of the world’s most water-scarce countries, where residents have protested against the industry’s expansion.

This week, the tech giant made a separate but related announcement. It plans to invest in water conservation along the Maipo River, which is the main water source for the Santiago region. Amazon will partner with a water technology startup to help farmers along the river install drip irrigation systems on 165 hectares of farmland. The plan is designed to save enough water to supply around 300 homes a year and is part of Amazon’s campaign to become “water positive” by 2030, meaning the company will conserve or replenish more water than it uses.

The reasons for this water initiative are clear: data centers require large amounts of water to cool their servers, and Amazon plans to invest $100 billion in building more data centers over the next decade. This is part of a major investment in its cloud computing platform Amazon Web Services. Other tech companies, such as Microsoft and Meta, which are also investing in data centers to support the artificial intelligence boom, have made similar water pledges amid growing controversy over the sector’s water and energy hunger.

Amazon claims its data centers are already among the most water-efficient in the industry, and plans to implement additional conservation projects to reduce its water use. But just like the company’s pledges to achieve “net zero” emissions, these water promises are more complex than they first appear. While the company has indeed taken steps to reduce water use at its facilities, its calculations do not take into account the enormous water demands of the power plants that power those same facilities. Without a broader commitment to mitigate Amazon’s strain on power grids, the company’s and other tech giants’ conservation efforts will only solve part of the problem, say experts who spoke to Grist.

The powerful servers in large data centers run hot as they process unprecedented amounts of information. Keeping them from overheating requires both water and electricity. Rather than trying to keep these rooms cool with traditional air conditioning, many companies use water as a coolant and run it past the servers to cool them down. The centers also require enormous amounts of electricity to run all of their servers: They already account for around 3 percent of U.S. electricity demand, a figure that could more than double by 2030. Add to that the coal, gas and nuclear plants that generate that electricity. himself drink even larger amounts of water to stay cool.

Will Hewes, who leads water sustainability at Amazon Web Services, told Grist that the company uses water in its data centers to eliminate energy-intensive air conditioning and reduce its dependence on fossil fuels.

“Using water for cooling in most places significantly reduces our energy use and so helps us achieve other sustainability goals,” he said. “We could always decide not to use water for cooling, but we absolutely want to because of these energy and efficiency benefits.”

To save on energy costs, the company’s data centers must evaporate millions of gallons of water per year. It’s hard to say for sure how much water the data center industry uses, but rough estimates are substantial. A 2021 study found that U.S. data centers used about 415,000 acre-feet of water in 2018, before the artificial intelligence boom. That’s enough to supply about a million average households annually, or about as much as California’s Imperial Valley takes from the Colorado River each year to grow winter vegetables. Another study found that the data centers operated by Microsoft, Google, and Meta took twice as much water from rivers and aquifers as the entire country of Denmark.

It’s almost certain that this number has increased even further in recent years as companies have built more centers to keep up with the boom in artificial intelligence, as AI programs like ChatGPT require huge amounts of server space. Tech companies have built hundreds of new data centers in the past few years alone and are planning hundreds more. One recent estimate is that ChatGPT requires an average-sized bottle of water for every 10 to 50 chat responses. The water consumption in these companies’ data centers could now rival that of a major beverage company like PepsiCo.

Amazon doesn’t provide statistics on its absolute water usage; Hewes told Grist the company is “focused on efficiency.” But the tech giant’s water usage is likely lower than that of some of its competitors — in part because the company has equipped most of its data centers with so-called evaporative cooling systems, which require far less water than other cooling technologies and only kick in when temperatures get too high. The company puts its water usage at about 10 percent of the industry average, and in temperate regions like Sweden, it uses no water to cool its data centers except during peak summer temperatures.

Companies can reduce the environmental impact of their AI business by locating it in temperate regions with abundant water. However, they must balance these efficiency concerns with concerns about land and electricity costs, as well as the need to be close to their large customers. Recent studies have found that data center water use in the U.S. has shifted “to water-stressed subsets” in places like the Southwest. But Amazon has located much of its operations further east, particularly in Virginia, where there is cheap electricity and financial incentives for tech companies.

“A lot of locations are driven by customer needs, but also by (prices of) real estate and electricity,” Hewes said. “Some large parts of our data center are in places that are not extremely hot and are not in regions with extreme water stress. Virginia, Ohio — it gets hot there in the summer, but there are large parts of the year where we don’t need water for cooling.” Still, the company’s expansion in Virginia is already raising concerns about water availability.

To mitigate its impact on such basins, the company also funds dozens of conservation and recharge projects like the one in Chile. It donates reclaimed water from its data centers to farmers who use it to irrigate their fields. It has also helped restore the rivers that feed water-stressed cities like Cape Town in South Africa. In Northern Virginia, it has worked to plant cover crops on farmland to reduce pollution from runoff in local waterways. The company treats these projects like other companies treat their carbon offsets: Each gallon recharged is credited toward a gallon it uses in its data centers. In its most recent sustainability report, Amazon said it was 41 percent of the way toward meeting its goal of being “water positive.” In other words, the company has funded projects that replenish or conserve just over 4 gallons of water for every 10 gallons of water used.

Despite all this, the company’s water-saving goal does not take into account the water consumption of the power plants that supply its data centers. That consumption can be three to 10 times higher than on-site water use, says Shaolei Ren, an engineering professor at the University of California, Riverside, who studies data center water use. As an example, Ren cited an Amazon data center in Pennsylvania that relies on a nuclear power plant less than a mile away. That data center uses about 20 percent of the plant’s capacity.

“They say they use very little water, but a lot of water evaporates nearby to power their data center,” he said.

Companies like Amazon can reduce this secondary water use by turning to renewable energy sources that don’t use nearly as much water as traditional power plants. Hewes says the company has tried to “lower” both water and energy needs through a separate goal of running on 100 percent renewable energy. But Ren points out that the company’s data centers require power 24/7, meaning intermittent renewables like solar and wind farms have a limited reach.

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Amazon is not the only company struggling with this problem. CyrusOne, another major data center company, revealed in its sustainability report earlier this year that it uses more than eight times as much water to generate electricity as it does on-site in its data centers.

“As long as we rely on grid electricity, which includes thermoelectric sources, to power our facilities, we are indirectly responsible for consuming large amounts of water in the production of that electricity,” the report says.

And as for water supply projects like the one in Chile, they too will only go part way toward reducing the impacts of the data center explosion. Even if Amazon is “water positive” on a global scale and has projects in many of the same basins where it has data centers, that doesn’t mean it won’t still threaten access to water in certain watersheds. The company’s data centers and their power plants may still use more water than the company replenishes in a given area, and water supply projects in other aquifers around the world won’t fix the physical consequences of that specific overdraft.

“If they can capture some of the growing water, clean it and return it to the community, that’s better than nothing, but I don’t think it really reduces actual consumption,” Ren said. “It masks a lot of real problems, because water is a really regional problem.”