UK needs better data centre water data, not honesty-based surveys

Data centres are thirsty beasts – and the rise in AI is exacerbating that problem. Well, very likely, at least, but we lack solid data.

Despite concerns that the UK’s AI ambitions could lead to water shortages, a report from TechUK suggests it’s not that bad on British shores: 51% of data centres surveyed use waterless cooling, and therefore 64% use less than 10,000m³ (or ten million litres) of water per year. This, the report notes, is less than a typical leisure centre and on par with a Premier League Football club. Football pitches remain the contextual measurement of choice, it would seem, in the UK at least.

According to the report, 44% of the data centres asked said they use a hybrid system that includes water but also may use air or a refrigerant for cooling, while only 5% are entirely water based.

“These results show that, contrary to some public perceptions, commercial data centres in England are not intensive water users,” wrote Luisa Cardani, head of data centres programme at techUK, in the report’s introduction.

Given the situation in the US, it’s natural that comes as a bit of a surprise.

Caveats ahoy!

All that said, the report only surveyed 73 data centres out of a total of more than an estimated 500. Plus, the report was completed alongside the Environment Agency, which has struggled of late to manage water supplies in the UK, to put it mildly.

The techUK report mentioned that the survey was voluntary and anonymous, which may lead to self-selection. Those who are good with water will take part, those who aren’t may just ignore the email. There has been no independent assessment of the data either.

Plus, the survey didn’t bother to ask any information about data centre size or load. That’s problematic given smaller facilities are inherently less of a problem anyway, and it’s the big ones we’re most worried about. One key metric that’s becoming more common is Water Usage Effectiveness (WUE), which aims to track how many litres are used per kilowatt hour; having that would have been useful.

Comparison to other water data about data centres

Indeed, the report’s claim that two thirds of surveyed data centres use less than ten million litres annually suggests that smaller facilities dominated this research.

A paper from 2016 found that a 1MW data centre using traditional cooling would use 25.5 million litres (6.75m gallons) of water annually. But that’s older data before new cooling techniques became more popular, which could account for some of the difference. Most data centres are now well above 1MW, too.

Data from the UK government suggests there’s 1,048MW in capacity around London, and reports suggest around 200 data centres in the region, suggesting an average of over 5MW each, though plenty will be much larger.

How much water do they use? We don’t really know, given many data centres don’t track their water usage. Indeed, one law firm’s investigation revealed that Thames Water has no idea how much water it supplies to data centres.  

A report from the US Lawrence Berkeley National Lab guessed that American data centres used 64 billion litres for cooling alone in 2023. Breaking that down by data centre is harder. As noted, size matters: researchers from University of Wisconsin-Milwaukee noted that the Google data centre using the most water was in Iowa with 3.8 billion litres each year, while another air-cooled data centre in Texas used just 38,000 litres.

Better water data needed

What would be helpful is if the companies building and operating such data centres had to share how much water they use, which some do via corporate responsibility reporting. In 2023, Google’s data centres used 23 billion litres annually for cooling, Meta used 2.9 billion litres.

“Because Google’s disclosures do not pair water consumption data with the size of centers, technology used or indirect water consumption from power, these are simply partial views, with the big picture obscured,” noted the University of Wisconsin-Milwaukee researchers.

Improving data collection and sharing is a requirement being discussed in the EU, which aims to also regulate data centre energy and water usage. The Royal Academy of Engineering called for similar plans in the UK earlier this year, while techUK echoed calls for better reporting and monitoring.

Without such data being collected and shared, we’re stuck with largely meaningless surveys at a time of big growth in data centres and water shortages. Thanks for trying techUK, but we’re all going to need to do better.

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