How thirsty are data centres? The truth about their water consumption
Posted on: 20 August, 2026
By Matthew Smith and Linda Serck
Hosepipe bans are rife across England during August 2026’s drought, yet Europe’s largest data-centre cluster in Slough is guzzling millions of litres a day of our precious water. At least, that’s the public perception. Is this really the case? Senior lecturer and programme leader Matthew Smith from the University of the Built Environment appeared on BBC Radio Berkshire to bust a few myths.
Our lawns are browning, garden hoses are coiled away, and that long-forgotten watering can is back in service. Hosepipe bans across England during August 2026 have affected more than 27 million people, with 71% of England’s land in drought. Against that parched backdrop, attention has turned to what appears to be a flagrant injustice: the general public are scrambling around, scrimping on showers, while great monolithic data centres seem to be quietly guzzling water from a tap nobody’s turned off. And with Slough being home to Europe’s largest cluster, housing 30 to 35 data centres, the finger is being angrily pointed in the Berkshire town’s direction.
Twenty-one thousand baths
Where water is used in data centres, its principal purpose is cooling. We can be forgiven for imagining our digital world as sitting weightless in the clouds but in reality, our day-to-day life is powered by data centres housing thousands upon thousands of servers, stacked in long rows of towering racks, floor to ceiling, and running every second of the day and night. They store our medical records, process our bank transactions, stream our choice of films, deliver our social media, and increasingly power our reliance on AI technology.
All that computing creates a lot of heat, as Matthew Smith, Programme Leader – BSc Real Estate Management at the University of the Built Environment, told BBC Radio Berkshire listeners:
“If you’ve ever had a laptop on your lap, it gets a bit hot. Imagine that heat multiplied tens of thousands of times. Data centres need water for evaporative cooling: it mists air inside systems which draw the heat away from the building so that the computing processes can carry on without any interruption.”
And with the high volume of computer hardware that needs to stay cool comes an eye-watering amount of water.
“In Slough, one of the biggest occupiers has a water abstraction licence, which means that they can draw water out of the aquifer under the ground, so they’re not taking this water out of the domestic supply necessarily, but it’s water that we all draw on, ultimately. One of those abstraction licenses is for 1.7 million litres a day, so you imagine taking 21,000 baths in a day – that’s how much water that they can use.”
If people can’t use hoses to water their allotments, why can these data centres get away with consuming so much water?
Matthew’s research into the water-cooling systems used in some of Slough’s data centres produced some facts that may surprise.
“Some data centres do use huge amounts of water, but actually others don’t,” he said. “The second biggest occupier at Slough hardly uses any water at all. And why is that? Because they use a closed loop system, a bit like the water cooling in your engine – it uses that water again and again. It doesn’t need to keep using fresh water to cool.”
So, on the argument of water-guzzling data centres, he concluded: “It depends on the data centre. First generation, early ones – yes, they use a huge amount of water. But we’re moving into technologies now where they don’t use so much.”
Are data centres exceptionally thirsty?
UK data centres are not required to report how much water they use, but the best available figures for England initially appear to support the image of an exceptionally thirsty industry. Research commissioned by MOSL, the market operator for England’s non-household water sector, estimates that data centres consume around 1.9 billion litres of drinking water a year.
This sounds enormous but, put into context, it represents just 0.2% of all non-household drinking-water consumption in England. The same research found that 67% of data centres use less than one million litres a year, while just six particularly thirsty facilities account for 65% of the sector’s entire consumption.
The type of closed-loop cooling system Matthew referred to above has changed the equation. Rather than continually drawing in fresh water and losing it through evaporation, the cooling liquid is recirculated and reused.
Other innovations have looked beyond conventional cooling altogether. Microsoft notably tested an underwater data centre off Orkney as part of Project Natick, with its experimental module spending two years on the seabed before being retrieved in 2020. More recently, Microsoft has brought that drive for lower-water cooling back on land, developing closed-loop, chip-level systems for new data centres which, once filled, can operate without consuming additional water for cooling.
Furthermore, some official data on data centres do not always present a UK-specific picture. Matthew described some of the government reporting on data centre water consumption as “quite alarmist”, stating that these reports tend to draw on data from America, “where they do use more of the water-based cooling systems”.
Indeed, the US figures are considerably more eye-opening. A major US study by Lawrence Berkeley National Laboratory estimated that American data centres directly consumed 66 billion litres of water in 2023, with hyperscale and large colocation facilities accounting for 84% of that total.
“In Europe we tend to use the closed-loop ones, so there’s not as much water being used in Slough and European data centres,” Matthew said.
There is more evidence to support that broader point. A 2025 techUK and Environment Agency survey of data centres in England found that 51% used waterless cooling, 44% used hybrid systems and just 5% relied on water-based cooling, although the voluntary survey may not be representative of the entire sector.
What are the bigger water guzzlers?
The 0.2% percentage shows that data centres are far from being the biggest users of the water supplied to businesses and public organisations. Earlier research for MOSL identified six broad areas that together account for around half of non-household water demand: agriculture; food and drink manufacturing; chemical manufacturing; hotels and food service; education; and health and social care.
So while 1.9 billion litres makes for an arresting headline, the reality is less dramatic. Data centres take a very small slice of England’s business water supply, with much of even that consumption concentrated among a handful of unusually water-intensive sites. During a drought, resentment is understandable when households are being asked to count every drop. But the evidence suggests that data centres should not be such a prime target for finger-pointing blame.
Matthew Smith is the programme leader for BSc Real Estate Management. Find out more about the degree here:
BSc (Hons) Real Estate Management
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