How much water do AI data centres actually use?

When you hear about a new AI data centre being built near you, I bet one of the first things you think about is how much water they use. As Nova Scotia announces its first large-scale $8 billion data centre, officials are quick to make comparisons. It's not going to use any more than our golf courses. The amount of water that, as I understand it, will be used at this plant is actually less than some fish plants. We're not going to be doing anything that is damaging or hurting the environment. So how much water do AI data centers actually use? Well, part of it depends on its cooling system. Data centers get hot because computer chips turn almost all of their electrical energy into waste heat. Open-loop cooling systems continuously draw water and circulate it to absorb that heat. It then spits out the water, and some of it evaporates. These centers use a lot of water to stay cool, especially in hot climates like Arizona or California. A study from the International Energy Agency estimates that data centers around the world used 140 billion liters of water just for cooling in 2023. But more of these data centers are turning to closed-loop systems, including the one they want to build in Nova Scotia. They're like your refrigerator. They're closed-loop. They go around. Water and coolant circulate. It heats up in the data center and then usually comes back out to external cooling stack and then flows back again. Think of it like how your car engine is cooled or your refrigerator. Usually the system is filled once with treated water and only replaced during maintenance. These closed-loop systems use much less water but that doesn't tell the whole story. Data centers are getting bigger and more of them are popping up. If you go back in history from the railways to the pipelines, the growth is slow. So communities can react better. Policy and research can keep up. Here's an industry where three years ago you were building on tens of acres, now you're building on hundreds to thousands of acres. How will anybody keep up with that? There's a reason so many big tech companies are looking to Canada. Our cooler climate makes it easier to keep these centres cold. One of the strengths of Canada for this industry is, as you can see today, it's a cool climate. It's actually more sustainable to do it here, so you're not wasting resources. The new centre in Nova Scotia would tap into the existing industrial water system at Landry Lake, which also serves the 3,500 residents of Port Hawkesbury. The company, Everwind, says once it's fully operational, it will use about 500,000 litres of water a day. It's an average that includes the water needed to fill the system up front. Officials say that's 1% of what's allowed to be used from the lake. It says any cooling fluid that's taken out during maintenance or the replacement of water will be recycled or disposed of off-site. But this doesn't account for water that's used indirectly. When we look at the water consumption of a facility, when you're using electricity, there's also a water component. So in Nova Scotia, there's a high percentage of the grid which is coal-based, and those coal facilities may use evaporative cooling. Everwind plans to eventually build four onshore wind farms to support the centre, but that's not how it will be powered to start. And the company says they've been told the grid has capacity. What they don't say is for coal-powered plants, those ones used in direct cooling, those require a lot of water. The more power you're going to be pushing out for more hours in the day, the more water that you're going to be using downstream. So back to those comparisons. Everyone says their daily water use will be less than a third of what a golf course uses. But don't golf courses use a lot of water? I think if you hate data centers, you should hate golf courses more. It's a niche sport that benefits the elite. It takes up an enormous amount of land and water. Data centers have a lot of potential. I think most people who are upset about the water usage of data centers don't have the numbers wrong, but they perhaps don't have the numbers in context. So when it comes to comparing how much water a data center uses to businesses like golf courses or fish plants, it's something we can easily understand. But is it really a fair comparison? The devil is in the details. But data centers are concerned, and remember, they're very well resourced. They know the tricks of the trade really, really, really well. So the PR material and the actual implementation, I'd be pleasantly surprised if I find it's the same. Part of the problem with knowing exactly how much water data centers use is the tracking. It's been hard to get detailed breakdowns from the big tech companies. This Quebec center opened in 2018 and didn't even have a water meter. For years, they didn't know how much water it was using. But town officials have promised the Nova Scotia facility will have a water meter. The regulations under the utilities stipulate that if you accidentally, one time, take too much water one month, that is an opportunity for us to invoke fines, to take you to court on that kind of thing for a one-time offence. But if you are routinely taking more water, there is a provision where we can just suspend your water and say you said you were taking this much and you're taking more and now you can't have that water anymore. What I would ask residents of these small towns, look at the permits, look at the designs. In the case of the new Nova Scotia data centre, a lot of these experts weren't overly concerned about its water consumption. What they are worried about is transparency. And as more big tech companies are thirsty for our resources, Canadians will be watching to make sure they keep their promises. Ali Thompson, CBC News, Halifax. Thank you.