Curious Conversations, a Research Podcast

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Travis

If you are listening to this podcast, are surely benefiting in some way, or form from data centers. Or data centers. While I'm not sure exactly what to call them, what I am sure about is that I've heard a lot about them recently, especially related to how much water they use as they start to pop up in different areas of the country. So I'm curious as to how much water a large data center actually uses, and what are they doing with all that water, as well as what are some things that we should be thinking about if they might move into your neighborhood. And thankfully Virginia Tech's Landon Marshton is an expert in this very topic and was kind enough to answer all these questions and more. Landon is an associate professor in Virginia Tech's Charles Evia Jr. Department of Civil and Environmental Engineering. He specializes in water resource engineering and his research focuses on the sustainability of water systems and the complex interconnections between water, energy, food, and infrastructure. So Landon was the ideal person for me to talk to about this topic. and he was able to break down for me about how much water a large data center would use and explain how they're using it. He also shared some of the things that he hopes that localities are thinking about as data centers start to pop up in different areas of the country. And he even made me feel a little better about a question I would often ask my parents about leaving the water on while I brush my teeth. I'm Travis Williams, and this is Virginia Tech's Curious Conversations.

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Travis

Well, I want to talk to you about data centers or data centers. I'm not really sure exactly which way I'm supposed to say that word, but one or the other and specifically related to water and how much water they use. So I guess I'm curious right off the bat, how much water does a data center use? there any way to quantify that?

Landon

Yeah. Yeah, great question. This is one I get a lot from journalists as well as residents who are concerned about data centers coming into their communities. Will this be a threat to the water resources? And I think it's good to look at this in two ways. First of all, from a national or regional perspective, data centers consume very little water relative to the rest of the economy. Most of the water that's withdrawn within the U.S. is for the food we eat, so for irrigated agriculture, and for the energy that powers our homes, our businesses, and Virginia Tech. And so those two sources constitute about 80 % of total water withdrawals for, again, irrigation and for thermoelectric power. Data centers get most of the water from a public water supplier, much like that delivers water to our houses, our businesses and our universities. And public water suppliers are about 12 % of water withdrawals nationally. Of that, of the total economy's water demand, data centers constitute a little bit under 0.04 % of total water demand. And so...It's a relatively small amount. see sometimes some sensationalized headlines suggesting data centers are a threat to national water security or using up all of our water. And I think at a regional or national level, that is not correct. However, data centers can use a significant amount of water at a very localized level and place strain on local water infrastructure. And so as you're seeing more and more data centers locate from traditional hotspots. And so that would be places like Northern Virginia is not only nationally, but globally kind of the most dense data center location. And we're seeing now places and more rural places in Virginia, as well as across the country, gain attention from data center developers. You've seen more and more data centers being built there. And one thing I want to highlight is why we use this term data centers to kind of refer to any type of data center. There's actually nuance or differences between different types of data centers. And so there's small like what's called so-called closet or enterprise data centers, which you might see in an individual company and in a, you know, just a small room to kind of set aside. And then you have everything from that on one extreme to what we call hyperscale data centers. And then so these can be like warehouse size, size of football fields. And now with some of these new developments for AI data centers, they might be the size of small college campuses. And so with that mean they have very different energy demands as well as water domains. And for these really large data centers, that are being proposed, some of these are suggesting that have five million gallons per day to as much as 10 million gallons per day water demand for these really large data centers. And so to put that number into context, I kind of put the national level values earlier to put that specific number into context, that's larger than about 80 % of public water supply demand, excuse me, that's larger than 80 % of US counties public supply water demand. And so most counties where data centers are coming in, their demand for these, again, these really large hyperscale data centers is gonna be larger than the whole community combined. So this has implications on the operations of that utility and infrastructure. And then we think about potential for things like stranded assets, if this is in fact a bubble, right? And these data centers maybe aren't there in a few years. And so that's where I think the real problem is and where maybe the concern is merited is when you think about...these more localized contacts and water infrastructure and operations of some of these facilities.

Travis

And so it sounds like maybe not a big deal nationally or maybe even regionally, but maybe at your local level, that's where you should really pay attention. That's kind of what I'm hearing from you.

Landon

Sure, that's right.

Travis

What is it about those larger data centers? What is it about them that makes them use so much water? What are they doing over there with that water?

Landon

Yeah, right. Right. So there's two ways that data centers use water. I'm kind of, they obviously have, there's some commercial side of that. they'll have, people using water like they would in the office building for drinking and for hand washing, but that's not where data centers use all this water.

Travis

They're not just taking a lot of baths.

Landon

No, they're not just taking a lot of baths here, you know, have overactive bladders and using the restroom a lot. Like this is not what's going on in these data centers. Right. Instead, there's two ways that these data centers rely on water. The one is I'll start with is a direct water usage within the facility itself. And this is what most people think about when you think about water usage and what are associated data centers is the water that's actually used within the data center. And they primarily use that for cooling. And so these server racks are very energy intensive. And I'll get to that later. That will be the second way that data center achieves lots of water. But when they generate, they use all this energy, they also need to dissipate a lot of heat. There are a lot of heats coming off these server racks. You think about like putting a laptop in your lap for a while and you know, it's warm after a while and magnify that like a million, right? This is kind of what you're seeing with these data centers. They generate heat, the heat needs to be dissipated. And so we need to do that using cooling. there's kind of several ways to cool a data center, but painting with broad strokes here, the two most generalizable ways are air side cooling versus evaporative cooling. Air side cooling uses ambient air temperature to basically cool the facility. This uses very little to no water, but on the other hand, it's very energy intensive. And so a lot of these large data centers, particularly ones for AI, which have very dense heating outputs, they need to use what's called evaporative cooling. So evaporative cooling uses water basically to dissipate that heat within the system. And in doing so, that water evaporates into the atmosphere and it needs to be replenished. And so this type of cooling system is very energy efficient. It doesn't use as much energy as the air side cooling but the trade off here is it actually consumes a lot of water. So this is primarily where data centers use water within their facility is for cooling, especially evaporative cooling. Now I mentioned that's one of the ways that data centers rely on the water resources. And in fact, from our study, if you look at this in a national level, this was a study we published in 2021. So it's a little bit dated at this point, because the field's evolving so quickly. About one quarter of the data centers overall water footprint could be attributed to that on-site water demand. However, that means three-fourths of their water demand is not happening at the data center itself. Instead, what's happening is, again, these data centers consume a tremendous amount of energy. In fact, there's some projections by some of my colleagues, one of my former PhD students who's published a report that went to Congress in December of 2024, kind of projecting out future energy demands of data centers that these data centers within the United States, might consume anywhere from 6.7 to 12 % of total electricity demand within the United States. So these things are consuming a lot of energy. Some of these are over one gigawatts, which to put that in context, you that's like the size of a decent sized city, several million households. And so these really large data centers can consume a lot of energy. And with that energy, often means they're connected to the same electricity grid that we're connected to. And in many places across the country, including in Virginia, we rely heavily on thermal electric power. So this is like natural gas, coal, nuclear, and these power plants often rely on water in the same way the data centers do to help dissipate that heat and to help turn and make, in this case, they actually use the steam to turn turbines and then eventually generate electricity. And so that water consumption that's used to generate electricity, if that's attributed back to the data center, then that can be encapsulated within its overall water footprint. So it's not just the direct water use that the data center itself for cooling, but if we were to think about all the energy that data center requires, and to then again attribute that water demand back all the way to the data center, this would encompass or make up this entire water footprint, which can be quite some.

Travis

Yeah, it sounds like there are some trickle down effects with a pun intended there to the desk and their use of water. I want to ask you a question and I'm going to preface it by, this is a question that I had when I was a young kid and no one really ever answered it for me. They just kind of blew it off. And it was when I would just leave like water running in my house and my parents would be like, you're wasting the water. And in my mind, I was like, where's it go? Can't we get it back? Where's it? Does it disappear? And this was my mind then. And so I guess I'm. In the context of this conversation, when we talk about a data center consuming water or really anything consuming water, what does that mean and why is it a concern?

Landon

So water consumption, even in my technical domain, like in the literature and stuff, this word consumption is used interchangeably for meaning a lot of different things. In the context of what I'm referring to consumption, what I mean specifically is that water is evaporated, transpired, or removed from the watershed, the location where the water is withdrawn, and it's not available for immediate downstream use by other water users. Oftentimes water can be delivered, let's say to your house, right? So you're actually maybe intuitive as a child, like water comes to your house. You let the water run for a long period of time, don't use it. And it goes down the drain. And then like, where does it go out from there? It disappears. Well, in most cases, it's going to go to a wastewater treatment plant and that wastewater treatment plant will treat that water. And then it will be returned back to a local river or stream, sometimes injected in underlying aquifer, but it's one of those water sources typically, right?

And then that water, if you're in the headwaters, like we are here at Virginia Tech, that means that water will then go travel downstream and eventually people that live further downstream will use that water again and again and again. Right? So it's available for those downstream uses. And data centers on the other hand, that water, most of that water is not returned back to the water body. In many cases, it's going to be evaporated. So it's going to go to the atmosphere, evaporate, it will eventually, you know, back into the hydrolytic cycle. And so it's going to turn into precipitation at some point and land back on the land surface or in the oceans, but it usually won't be local, right? So that water kind of leaves that local basin of interest and goes somewhere else. And so for places that are dealing with water scarcity and really value water because it's so limited, this can be problematic, right? Because you're basically taking that water that maybe would have been used for, yeah, you're using it in the sink and then that water can be treated and used again and again and again. In this case, it's gone. There's no opportunity to use it by downstream water users. And so that can be an issue in many cases.

Travis

That's a much better answer than my parents were ever able to give me. So thank you. Sure. Well, what are some things that we can do to maybe help mitigate some of these concerns? Are there some things we can do? Maybe that's a better question.

Landon

Right, right. So I mean, I think the best mitigation strategies are likely not with you or me, as individuals. I certainly people would say, well, maybe, you we are so dependent on these data centers, they underpin our digital life. So from our streaming Netflix to this very conversation we're having using this is relying on a data center. All the photos we upload, right? Like Chad's WT, like any prompt is going to use rely on data centers that has energy and water implications associated with it. But the reality is those are relatively minuscule in the grain context of how these data centers are using energy and water. I think the real risk that I mentioned earlier on the water side, which is a little bit distinct from the energy side, those are more pronounced problems. On the water side, my major concern is as these data centers begin to increasingly grow in size, one, two, increasingly expand into new areas, particularly rural areas that maybe don't have the resources from a water utility standpoint to navigate some of these unique challenges associated with data centers, that some of these costs, these infrastructure costs, because when we're talking about water resources, and it's true also of the energy sector, there are a lot of upfront fixed infrastructure costs to delivering water and energy to end users. And those costs are usually, again, mostly upfront and then distributed over long periods to kind of payback periods, right? And so I think one legitimate concern that I've heard voiced that I agree with, is that you have this possibility of this asymmetry in kind of knowledge and power perhaps between these large tech companies and some small, know, rural water utility that's never dealt with the data center before coming in and having inequitable terms within their contracts or agreements that may be offload some of these costs onto local community or the residents or maybe don't have provisions in place that guarantee securities in case the data center were not to expand in the way that they promised or to leave town after a few years. And so the risk there is that all this upfront infrastructure is being developed and with promises of being paid back later. And then again, the data center maybe doesn't fulfill those promises, then who's left on the hook for those costs, right? I think that's a real concern moving forward and not say those are insurmountable, right? think with proper planning, those can be overcome as well. And this can be a true benefit to not only the data centers, but also the communities as well, because there are some tangible benefits that come along with it. don't generally data centers don't offer a lot of jobs, but they can improve tax bases, especially in rural areas that are looking to renew sources of tax revenue. But I think many local communities have to be cognizant of some of the challenges that come along with them and make sure that they're properly prepared to handle those challenges as they come and really thoughtful contracts in place to protect themselves against potentially bad actors.

Travis

Yeah, I'm glad that you mentioned that because one of the things I was going to ask you is you having this knowledge, studying this subject, what do you hope that when the leaders of your community maybe consider a data center, what types of things should they be thinking about?

Landon

Right. mean, this idea was stranded assets, right? To make sure that there's provisions in place to make sure that the rate payers aren't going to be responsible for that in the future, that they're not effectively subsidizing the risk of these data center developers. I think is one key provision. There are several folks that are more knowledgeable than me in terms of these contract agreements, but that's kind where I would lead you is to kind of look in that direction to understand some of those risks and to make sure those are written up in any contracts to protect these communities from those risks. And when it comes to water supply specifically, again, generally in most areas in the Eastern United States, it's not going to be...a huge threat, I'm not gonna say all, but in many places, it's not gonna be a huge threat to overall water supplies for most data centers. But you can have challenges, especially if you have these really large, hygroscale data centers, located in maybe certain headwaters where water availability is more limited. You have the costuring where several these data centers co-locate, then you can start, know, then it starts becoming more pronounced. But in many cases, you know, irrigating agriculture is gonna be...the dominant, especially when you go out kind of the Midwest and further out West, Irrigate Air will just be the dominant water user, even when you consider these really large data centers. And so I think just the point of that's kind of my talking with you today is just to help folks contextualize how water is used within the data center industry. There's a lot of sensationalized headlines that suggest they're a major threat to water supplies. Again, I think at a national level, that's probably a little bit misplaced, but at a local level, when you talk about water infrastructure, you get into some of financing issues, I think that's where the real challenges and issues need to be addressed.

Travis

Yeah, well, that's, that's great to hear. It's especially great to hear that it's not so much my use of Chat GPT or this podcast that's causing these problems.

Landon

I mean, we all contribute, we all play a role. Don't working in this field for a while. And there's been a lot of discussion about, changing people's diets and things like that. I think that's a tough route to go from a policy perspective to try to get people to change their behavior and patterns in such a way that it's going to dramatically reduce our water footprint. think a more probably realistic way is to work directly with these companies and provide incentives and regulatory frameworks that would make sure they make the best decisions not only for themselves but also for the communities that they reside in.

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Travis

And thanks to Landon for helping us better understand data centers and water usage. If you or someone you know would make for a great curious conversation, email me at traviskw at vt.edu. I'm Travis Williams and this has been Virginia Tech's Curious Conversations.

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