Water UK, the trade body representing water companies in Britain and Northern Ireland, has warned that the UK will not have enough water for future datacentres, criticising the government's AI growth plans as 'fatally flawed'. Datacentres rely on large amounts of water for cooling, with cooling towers, chillers and humidification systems using water directly, and large volumes consumed indirectly through high electrical power needs.
Government forecasts 'fatally flawed'
In a publicly available written briefing to MPs, Water UK stated that the government's water forecasts 'explicitly exclude' datacentres and are 'fatally flawed'. It noted that the government 'makes not a single mention of water' in its policy for delivering AI growth zones, its AI for science strategy or its AI opportunities action plan. The Environment Agency's most recent national framework for water resources, published in June 2025, also failed to include an estimate of datacentre water demands.
'There appears to be an assumption that the country will always have enough water for its economic needs,' the briefing said. 'Nothing could be further from the truth.'
Water-stressed regions
Water UK said datacentres are already being built in water-stressed areas, with more than three-quarters located in the south and east of England. Millions of people in these regions have been placed under hosepipe bans after prolonged extreme heat and lack of rainfall. The trade body warned that any new datacentre growth in these areas 'may be impossible' without policy change due to existing pressure on the network.
'As leakage and demand targets are already very ambitious, the only solution to deliver new supply is to increase the amount of water taken from the environment – which may be harmful – or to build new supplies, and major reservoirs can take 15 years to plan and build,' Water UK wrote. It added that water companies have cut leakage by around 40% since privatisation and plan to reduce it by a further 17% by 2030.
Slough datacentre concentration
The UK's highest concentration of datacentres is in Slough, served by Affinity Water. About 125 datacentres are proposed or under construction in Affinity's region, much of which is subject to a hosepipe ban. In May, Affinity told MPs that some datacentres were requesting up to 3m litres of water a day, equivalent to the peak water demand of 3,500 homes.
'The planning framework is built around household growth and per-capita consumption, and has not adapted to commercial users whose water needs can match those of a market town,' Affinity said in a written submission to the environmental audit select committee.
Drinking water use
Due to Environment Agency permitting, datacentres are currently required to use only drinking water. Water UK estimated that datacentres in England use 6.6m litres of drinking water every day. With the government's ambition to triple datacentre capacity by 2030, this could increase to 19.8m litres a day. Jon Chappel, Water UK's deputy director, called this 'unforgivable' and a 'genuine failing of government'.
England's current water shortfall is 220m litres more a day than assumed in water forecasts. Water UK said this deficit is currently being met by 'accepting a greater risk of environmental harm, and restrictions on water use in the event of drought'. Similar concerns have been raised in Ireland, where hosepipe bans have ignited criticism over a lack of clarity about datacentres' water usage.
Critical national infrastructure
The government has designated datacentres as critical national infrastructure, meaning their loss or compromise could result in 'major detrimental impact on the availability, integrity or delivery of essential services' and 'significant impact on national security, national defence, or the functioning of the state'. Oliver Hayes, head of big tech and campaigns at Global Action Plan, said it was not clear why datacentres had been given this status, but that water companies may be powerless to restrict their water use as a result, potentially prioritising datacentres over households at peak water demand.
'I think it is highly likely that we're going to end up seeing datacentres that are actually running chatbots, or enabling people to do benign and very wasteful, pointless things, protected and given favourable treatment when it comes to resources,' Hayes said.
Drought hierarchy needed
Chappel said Water UK had asked the government to publish a drought hierarchy to set out which sectors are prioritised in times of water shortages, but ministers had yet to do so. 'Without this there will be a trade-off across society,' he said.
At the end of June, water companies, Ofwat, the Environment Agency, the Met Office and Natural Resources Wales announced a £75m campaign to encourage people to use less water. Water use per person in England and Wales is among the highest in Europe. The government was expected to publish a national policy statement for AI growth in February, but this has been delayed.
A government spokesperson said: 'The environment and sustainable development must go hand-in-hand and we will protect our water supply while unlocking growth, including looking at alternatives or ways to minimise impact on supplies and output of wastewater from datacentres. We are also taking decisive measures to secure water supplies and meet higher demand, including record levels of infrastructure investment and building nine new reservoirs.'
