Rain fell in Slough last week, but the brief downpour did little to change the picture for a town that, like much of southern England, has endured a month of intense heat under a hosepipe ban.
Across the area, lawns and public parks are still scorched and straw-coloured, while children’s paddling pools remain packed away in garages rather than filled for summer afternoons.
Slough is formally classed as a “water-stressed” area, a designation used where demand for water is already close to — and in some cases greater than — the supply available, even in normal conditions.
After repeated heatwaves, the strain has deepened. Thames Water’s reservoirs are currently 74 per cent full, well below the 87 per cent capacity typically expected at this point in the year.
Urging customers to conserve supplies, Thames Water said: “Small changes, such as taking shorter showers, turning off taps and avoiding non-essential water use outdoors, all help to reduce pressure on our network.”
But not everyone is mucking in. When local residents look up at the cooling towers on the Slough Trading Estate, they see a different world: one where there seems to be no shortage of water whatsoever.
That’s because Slough’s commercial premises are not subject to the hosepipe and sprinkler ban. Indeed, they can use as much water as they like.
And that’s bad news for Thames Water’s private customers because Slough’s industrial zone has become a hub of Britain’s burgeoning data centre industry, with 32 of them housed within the town. They consume water as greedily as camels at an oasis.
A graphic showing dry and cracked earth and a data centre which is under contruction in Slough
An LED screen displaying Artificial Intelligence (AI) during a press conference on August 25
An aerial view of an under-construction Equinix data centre in Slough pictured on August 26
Frustratingly, there is no publicly available data that reveals exactly how much water each data centre uses but, according to the trade body TechUK, one in 25 of them uses more than 100,000 cubic metres of water every year. And 14 per cent of them are using between 10,000 and 100,000 cubic metres.
On closer inspection, however, it only seems to have surveyed 72 of the 500-plus data centres in Britain. How much water is used by the other 400-odd is anyone’s guess.
To put this in context, 100,000 cubic metres equates to the amount of water consumed by 3,000 households, the volume required to fill 40 Olympic-sized swimming pools and is ten times as much as is used collectively by England’s 2,200 golf courses.
Unfortunately, a data centre’s water consumption goes up massively during the hot summer weather – at precisely the time water is most likely to be in short supply.
US research suggests a data centre can consume 25 times as much water on a summer day as on a winter one.
They require large amounts of water because they are voracious consumers of energy: Slough’s data centres are estimated to gobble up 65 per cent of all the electricity consumed in the town.
Such huge energy consumption generates vast quantities of waste heat, which has to be dissipated somehow.
While around half of all data centres use air cooling, the larger ones tend to use water cooling systems, which rely on evaporation to bring down the temperature.
The new data centre was built on the former Akzo Nobel ICI Paints Manufacturing site in Berkshire
A Thames Water van pictured as employees carry out works in Wimbledon, southwest London
There will be three data centre buildings and digital service warehouses at the 11.5-acre site
Despite the data centres’ vast appetite for water, however, local residents claim that they can still feel the heat from the bases.
According to a Cambridge University study published earlier this year, a large data centre is theoretically capable of raising temperatures in its vicinity to the tune of 2C.
That said, because the effect is so heavily localised, there is little evidence to suggest that the town of Slough as a whole is suffering from the heat more than other places nearby.
On August 13, when the village of Wisley, 20 miles away in Surrey, recorded the year’s maximum temperature of 38.1C, Slough’s weather station – which lies half a mile from the cluster of data centres – peaked at a slightly more bearable 37.6C.
But the data centres’ thirst is increasing exponentially as the tech giants’ artificial intelligence (AI) models become ever more complex.
In 2023, a University of California study calculated that a data centre will consume the equivalent of a half-litre bottle of water for every 10 to 15 tasks it is asked to perform.
As a large data centre will undertake many millions of such tasks a day, that adds up to a big strain on the water supply.
Yet the dizzying increase in the power of AI models suggests that this estimate may be already out of date.
Their demand for electricity is already increasing remarkably. A study by the Massachusetts Institute of Technology estimated that Meta’s AI model Llama 3, introduced in July 2024, consumed as much electricity to perform a task as simple as producing a travel itinerary for Istanbul as it takes to ride an e-bike six feet.
Months later, however, an improved version was using as much electricity as it takes to propel the same bike 400 feet.
With the increase in power consumption comes a proportional increase in water usage. Google, for example, reported that its water consumption increased by 34 per cent in 2025 alone. In evidence to the House of
Commons Environmental Audit Committee last month, Water UK – the trade body for the water industry – warned that the government’s policy of trebling the number of data centres in Britain by 2030 has failed to take account of the amount of water they consume.
Slough now reportedly has the biggest number of data centres in Europe and more are set to be built
A woman’s hand checks the water temperature in the shower
Data center computer racks pictured in a network security server room
It stated: ‘Despite the extraordinary growth envisaged and desired, the government has all but forgotten that most data centres require water to cool their systems. The government’s forecasts for England’s future water needs also explicitly exclude data centres.’
Water UK also pointed out that water scarcity is already compromising the government’s house-building plans and preventing other sorts of businesses from expanding. ‘The situation is so bad that, solely due to a lack of water, the Environment Agency objected to a cancer hospital being built near Cambridge,’ it added.
Yet data centres can sidestep restrictions put on other forms of development because, two years ago, the government designated data centres as Critical National Infrastructure, meaning that they can be rushed through the planning system.
Water UK’s words are echoed in a report by the Government Digital Sustainability Alliance, which draws its members from government, tech companies, academia and the non-profit sector.
It describes the refusal to take water usage into account as ‘a systemic planning failure, indicating a disconnect between the nation’s digital economy growth ambitions and its fundamental resource management strategies’.
In other words, the government has geared its growth strategy so much around water-hungry data centres that it risks reducing the rest of the economy to a constant state of thirst.
Not only that, data centres are sucking ever more power from an already over-stretched electricity grid.
In 2024, they are estimated to have drawn 2,400 gigawatt-hours of energy, two per cent of Britain’s total energy consumption.
Last month, Energy Minister Lord Hunt, in answer to a question in the House of Lords, revealed that this figure had already grown to 2.5 per cent. And things will only get worse.
In March, North Lincolnshire Council granted planning permission for what will be Britain’s largest data centre yet: Elsham Tech Park, on a 435-acre site near Scunthorpe.
The government has designated North Lincolnshire as a growth area for data centres partly because of a large number of wind and solar farms in the area, but their energy supply is not reliable enough for a data centre.
And it has the potential to draw power of one gigawatt, which represents about three per cent of Britain’s average power demand.
A hand turns off a kitchen faucet after filling up a glass with water
A woman wearing a grey t-shirt stands holding a hosepipe as she washes her car with water
US research suggests a data centre can consume 25 times as much water on a summer day than a day in winter
While the plans include a gas power station on site, this would produce a maximum of 50 megawatts – 5 per cent of what the data centre is projected to consume.
So the Elsham plan also includes provision for an astonishing 650 back-up diesel generators, each one of them producing 2.5 megawatts, or as much power as 25 diesel cars.
While the rest of us are told we might be subjected to surge pricing or rationing on cloudy, windless days, Elsham data centre will be able to keep going by spewing out vast quantities of diesel fumes.
As diesel is a particularly dirty form of fossil-fuel powered generation, a single data centre will blow a huge hole in former Energy Secretary Ed Miliband’s dream of a near carbon-free electricity grid by 2030.
Then there’s the small matter of water consumption. The planning application for Elsham includes sections on the welfare of bats and breeding birds, as well as minutiae such as making provision for staff to be able to cycle to work, but it hardly addresses the issue of water use at all.
This is because the developers behind the tech park, Greystoke Land, say they will use a ‘closed loop’ cooling system which keeps on circulating water without any need regularly to top it up.
It’s a system that is becoming increasingly popular in data centres around the world and most of the relevant bodies appear to agree that it works.
According to Water UK, cooling systems of this sort can reduce water consumption to less than one per cent of other data centres.
And North Lincolnshire Council says that it accepts the plant’s water use will be ‘minimal’. But use of the closed loop system comes at a hefty price: it makes a data centre even more power-hungry.
When former Prime Minister Sir Keir Starmer revealed his vision of the UK becoming a world powerhouse in AI last January, he seemed to take no account of the impact of data centres on our water and energy supplies.
He also rode roughshod over the views of people who might one day find such a centre on their doorstep.
In the same month, planning permission was granted for a 20-acre data centre on Green Belt land next to Mimms service station on the M25 – another water-stressed area.
Housebuilders and other developers have been kept off the land for 70 years on environmental grounds but now it appears that, if you want to build a data centre, it is fine to eat into the increasingly scarce precious fragments of countryside left around London.
Data centres may appear to be shining beacons of a modern, clean economy but, in reality, they are energy, water and land-hungry monsters – far more so than the cotton mills which symbolised the industrial revolution.
As so little serious thought has been put into how they can be accommodated, they threaten to overload our infrastructure.
Britain is a country that has not only failed to build a single reservoir in 30 years but closed down its coal-fired power stations prematurely as part of the mad dash to net zero.
As a result, we are suffering endless water shortages (the current hosepipe ban was introduced despite a wet winter).
And the electricity grid is struggling to cope, running into serious problems in June’s heatwave, which apart from increasing demand for electricity to run air conditioning units and fans, made power stations less efficient and transmission wires less effective.
It is one thing to promise that Britain will become an AI powerhouse, quite another to tell people that they can’t water their lawn, or even have a bath or a long shower because the data centre down the road needs the water.
In the government’s headlong rush to make us one of the world’s AI superpowers, something is going to have to give.
