Data centers have become a growing source of debate in communities across the country. As artificial intelligence, cloud computing, streaming services and other digital technologies expand, so does the infrastructure needed to support them.
One issue increasingly at the center of that discussion is water.
Large data centers can use substantial amounts of water, leading to concerns that these facilities could strain municipal supplies or compete with residents and businesses for an increasingly valuable resource. Those concerns aren't without merit. But the reality is more complicated than the often-repeated claim that data centers simply consume enormous quantities of drinking water.
Understanding the issue begins with understanding why data centers need water in the first place.
Why Data Centers Need Water
Thousands of servers operating continuously generate enormous amounts of heat. Keeping that equipment within safe operating temperatures is one of the fundamental requirements of running a data center.
There are several ways to accomplish that.
Traditional air cooling uses mechanical chillers, air conditioning and fans. These systems can operate with little or no water, but they may require more electricity.
Evaporative cooling takes a different approach. Water absorbs heat and is cooled through evaporation, significantly reducing the electricity required for cooling. The tradeoff is obvious: some of that water is lost to the atmosphere.
Closed-loop systems continuously circulate water through sealed pipes and heat exchangers. Because the water is reused rather than intentionally evaporated, these systems can dramatically reduce water consumption.
Newer technologies are pushing that concept further. Direct-to-chip liquid cooling carries coolant directly to processors, while immersion cooling places computing equipment in nonconductive cooling fluids. These approaches are becoming particularly important as artificial intelligence and high-performance computing create much greater concentrations of heat.
The important distinction is that there is no single type of "data center cooling." Two facilities of similar size can have dramatically different water requirements depending upon their design.
How Much Water Are We Talking About?
This is where many of the alarming headlines originate.
A large hyperscale data center can use millions of gallons of water per day under peak conditions. A medium-sized facility might consume roughly 100 million gallons annually.
Those are significant numbers.
Viewed nationally, however, data centers still represent a relatively small portion of total U.S. water withdrawals compared with sectors such as agriculture and power generation. The bigger concern is often local rather than national.
A large data center built in an area already experiencing water stress can have a much greater effect than the same facility located somewhere with abundant water resources.
The source of the water matters as well.
Historically, many facilities have relied upon municipal drinking water or groundwater. Increasingly, however, operators are turning to reclaimed wastewater and other non-potable sources that do not directly compete with household drinking-water supplies.
That distinction can fundamentally change the impact a data center has on its surrounding community.
Myth: Data Centers Are Draining Communities Dry
Reality: Sometimes data centers can place substantial pressure on local water supplies, but there is no universal answer.
A large facility using evaporative cooling and municipal drinking water in a drought-prone region deserves careful scrutiny. A facility using closed-loop cooling and reclaimed wastewater presents an entirely different situation.
National statistics can therefore be misleading in either direction. Data centers consume only a small percentage of America's total water, but that doesn't mean a particular facility cannot have a significant local impact.
Location, cooling technology and water sourcing all matter.
Myth: Every Gallon Used Is Gone Forever
Reality: Water withdrawal and water consumption are not the same thing.
Water withdrawal measures how much water enters a facility. Water consumption measures how much is actually removed from the local water system, primarily through evaporation.
In evaporative cooling systems, a large percentage of the water can indeed evaporate. Some water, however, is discharged as wastewater that can be treated and returned to the water cycle.
Closed-loop systems change the equation even further because the same water is continually recirculated.
The meaningful question therefore isn't simply, "How much water does the data center use?"
It's also, "What happens to that water?"
Myth: Data Centers Must Use Drinking Water
Reality: They don't.
One of the most promising developments is the growing use of reclaimed wastewater for cooling.
Instead of drawing treated drinking water from a municipal system, facilities can use water that has already passed through homes and businesses, been treated by a wastewater facility and would otherwise be discharged.
Major technology companies are increasingly pursuing these arrangements with local utilities.
That creates the possibility of a more circular system: wastewater becomes a cooling resource rather than waste, reducing demand on drinking-water supplies.
The Water-Energy Tradeoff
There is another complication that is often overlooked.
Reducing water consumption doesn't automatically eliminate environmental costs.
Evaporative cooling became popular partly because it is extremely energy efficient. Replacing it with waterless mechanical cooling can reduce water consumption while increasing electricity demand.
Conversely, a cooling system that consumes more water may require less electricity.
Engineers therefore have to balance water usage, energy consumption, climate conditions and operating requirements rather than optimizing a single number.
New direct-liquid and immersion cooling technologies could improve that equation substantially, particularly in the high-density computing environments required for AI.
The Overlooked Issue: Water Quality
Most public discussion focuses on how much water data centers consume. Equally important is what happens to the water they discharge.
Cooling-system wastewater can contain concentrated minerals and chemicals used to control corrosion, biological growth and scale.
That means communities evaluating data center projects should be asking not only how much water will be withdrawn, but how wastewater will be treated and monitored before being returned to municipal systems or the environment.
Real-time monitoring and on-site water treatment are increasingly becoming part of sophisticated data center operations.
In some cases, tomorrow's data center may effectively contain its own miniature water-treatment facility.
Toward More Water-Smart Data Centers
The industry is already moving toward several approaches that could substantially reduce its freshwater requirements.
Reclaimed wastewater is replacing drinking water at some facilities. Closed-loop cooling systems are reducing evaporation. Direct-to-chip and immersion cooling are attacking heat closer to its source. Operators are improving filtration so cooling water can circulate longer before replacement.
Renewable energy can indirectly reduce water consumption as well. Traditional power generation itself can require significant quantities of cooling water, while wind and solar generation generally require far less operational water.
Data center operators are also facing greater pressure from communities, regulators and investors to disclose how much water they use, where that water comes from and what happens to it afterward.
Finding a Balance Between Bytes and Drops
Data centers aren't going away.
They support nearly everything that has become part of modern digital life — cloud applications, banking, streaming entertainment, business systems, social media and, increasingly, artificial intelligence.
But their growth creates legitimate questions for the communities in which they operate.
The debate shouldn't be reduced to whether data centers are either harmless technological infrastructure or enormous water-consuming industrial facilities. They can be either, or somewhere in between, depending upon how they are designed and operated.
The better questions are more specific.
Where will the water come from? How much will actually be consumed? What cooling technology will be used? Can reclaimed water replace drinking water? How will wastewater be treated? And how will usage and water quality be monitored?
Those questions turn an emotional debate into an engineering and resource-management discussion.
Data centers unquestionably require resources. But newer cooling technologies, recycled water systems and better monitoring are creating opportunities to dramatically reduce their freshwater footprint.
Ultimately, the question isn't whether our increasingly digital society will need data centers.
It is how intelligently we choose to build them.
