'Waterless' Data Centers Aren't Always The Most Sustainable Choice
As more data centers rise in desert communities and provoke concerns over their massive water consumption, the developers of these facilities are increasingly highlighting their ability to build “waterless” data centers. But when it comes to whether such a data center is actually the most sustainable option for a specific community, the waters can be murky.
The data center industry’s record growth over the past three years has led to greater public scrutiny of the sector’s environmental footprint and sustainability practices. While the brightest spotlight has focused on the enormous amounts of energy these facilities consume, their water consumption is drawing greater attention as data center development booms in desert and water-stressed markets.
Places like Phoenix, Las Vegas and Reno, Nevada, are some of the fastest-growing data center hubs, and residents in those regions are increasingly aware that data centers can use as much as 5 million gallons of water each day to cool the thousands of heat-producing servers inside.
Amid this heightened scrutiny, many of the world’s largest data center providers are touting data centers that use no water at all on-site for cooling. These technologies aren’t new, but they are now getting increasingly prominent placement in marketing material and public relations efforts from most major data center developers.
Firms like Aligned Data Centers and Edged Energy have made “waterless” or “zero-water” designs central to the outreach around planned campuses in locations ranging from Arizona to Illinois, while Novva’s website highlights “water-free cooling systems” at its Utah, Colorado and Las Vegas facilities that it says will save over 300 million gallons of water annually. Compass Datacenters has used waterless cooling systems since 2011, but over the past two years, it has made a concerted effort to draw attention to these technologies that allow it to “operate in even the most drought-stricken areas of the country.”
Critics contend that in many locations, the actual sustainability benefits of waterless data centers can fall well short of what the marketing suggests. They say claims of being waterless are often misleading because they ignore the water footprint of the energy the facility uses, while water-free cooling systems generally use more power — and therefore more off-site water — than the most efficient data center designs.
Even if a data center doesn’t consume a drop of water on-site, it is still consuming dozens of megawatts of electricity that in most cases come from fossil fuel or nuclear power plants that themselves use large amounts of water for cooling. But many data center providers don’t keep track of this type of causal water impact from their energy supply chain the way they would the carbon emitted by these same power plants, industry experts said.
“The concept of waterless data centers is a bit misleading,” said Shaolei Ren, a professor of electrical and computer engineering at the University of California, Riverside, whose work examines the water impact of data centers. “If this logic holds true, then any data centers, even those without any green energy, can be called carbonless because data centers literally have no on-site carbon emissions.”
Data center industry leaders strenuously pushed back on the suggestion that eliminating on-site water use is little more than greenwashing. While there is broad acknowledgment that a data center being waterless doesn’t guarantee it has less impact on a local watershed, they say these systems are a key tool in a sustainability kit.
“You need a menu of different choices for sustainability, different levers and buttons you can tweak based on region and the availability of things like power and water,” said Sean Farney, JLL’s vice president for data center strategy in the Americas. “Waterless data centers do use technologies that may make you draw more power, but in areas that are in drought and where water is a precious resource, it can be a good thing and may be worth that trade-off, especially if they have a lot of green energy.”
But even if calling a data center waterless may be marketing hyperbole, the possibility that such a cooling system could cut a data center’s water usage by millions of gallons would appear to be a clear-cut sustainability win, particularly in locations where water resources are strained. But this isn't always the case, according to Ren. The problem, he said, is that water-free cooling uses more power than the most efficient water-intensive systems.
“It uses more energy,” Ren said. “And if you consider the causal water footprint, that actually might be even higher because generating electricity requires lots of water.”
Ren pointed to a water-free data center Microsoft is developing near Hyderabad, India. While cooling systems in data centers operated by Microsoft typically use evaporated water and are some of the most energy-efficient data centers in the world, a 2023 study co-authored by Ren showed the waterless Hyderabad data center required twice as much power for cooling. According to the study, the 1.7 million gallons of water used each day to produce this additional power places the facility in the top third of Microsoft’s portfolio for water consumption.
But many industry insiders say looking at a data center’s total water use, unlike its carbon footprint, doesn't necessarily paint an accurate picture of whether the facility’s cooling design and water strategy are the most sustainable option at a given site.
While a data center might be located in a water-stressed area, the power it uses may not be generated in the same watershed or even the same region, said Kyle Myers, CyrusOne sustainability lead and vice president for environmental, social and corporate governance. In such a case, switching to waterless cooling, even if it drives up total water use, would reduce the facility’s impact by transferring water consumption from a stressed watershed to an area with more abundant resources.
“Climate change and greenhouse gases are global, but water is regional,” Myers said. “It matters exactly where you’re consuming the water, and if it’s plentiful there or not, that’s the critical question when you’re doing this analysis.”
A number of variables can change the math regarding whether eliminating on-site water consumption is actually the most sustainable option, Myers said. It isn't just where the power is being generated but also how.
Different types of power plants have vastly different water footprints, with fossil fuels and nuclear generally using significant amounts of water for cooling and renewables like wind and solar using none. The combined water footprint of the energy mix on a regional grid is a key element in determining whether waterless cooling makes sense, Myers said.
These were the key considerations in CyrusOne’s decision to transition its Carrollton, Texas, data center to waterless cooling in 2020, according to Myers. While switching to water-free cooling meant the facility used more power, an analysis of the water footprint of energy from the Electric Reliability Council of Texas grid found that, even with the additional power use, the data center’s total water footprint dropped by more than 5 million gallons between 2019 and 2020. The decision also meant that instead of pulling water locally in water-stressed Carollton, the data center’s water footprint was effectively spread among 13 watersheds.
The considerations around waterless cooling also vary between different kinds of data center providers. While the most efficient evaporative cooling designs have been favored by hyperscale cloud giants, many colocation providers have long used a fundamentally different cooling strategy with a design quite similar to waterless systems. These data centers are generally not as energy-efficient as hyperscale facilities with cooling towers, but the design is better suited to the economics and logistical needs of multitenant facilities.
From this less energy-efficient starting point, providers like QTS told Bisnow they have been able to build waterless data centers that use less power than previous models.
“We're more energy-efficient while also using virtually zero water. It’s better than if we were using it,” said Travis Wright, vice president for energy and sustainability at QTS.
Wright credited a flurry of design innovation around waterless cooling systems over the past five years that has made these systems significantly more efficient. He also pointed to the ability to install waterless cooling in stages, compared to the centralized water-based systems favored by hyperscalers. He said this creates efficiency for colocation providers, allowing them to improve efficiency by building out cooling infrastructure as tenants come on board.
“There was a loss of efficiency in the other system for the whole path from the startup of the facility through being 100% full, which can be a long time in a colocation facility,” he said. “In the dry systems that we use now, we get to install these things as they’re needed for each slice of the building and can run them at optimum efficiency from Day 1.”
Wright and Myers said waterless cooling isn't a one-size-fits-all solution, even in drought-stricken areas where water is a coveted resource. But they said they expect waterless to be the preferable option at a growing number of sites. A wave of renewable energy projects is greening power grids and lowering the water penalty for higher energy use. Myers also pointed to a steady rise in markets officially classified as water-stressed. Providers are starting to see that abundant water now is no guarantee it will still be available a decade from now.
“Our weather patterns are changing, and they’re going to continue to change,” Myers said. “The danger of building water-consuming technology in places where water is currently plentiful is that it may not be in 10 to 20 years.”
