Zack Polanski has called for a freeze on the approval of new data centres in England because of concerns about the amount of water and energy they use.
The Green Party leader said the government should introduce stricter environmental rules and give communities more say on whether the centres are built in their area.
Data centres can use significant amounts of water to cool their systems, although there are no official figures on how much water they consume in the UK.
The government said a pause would lead to the UK losing investment and being dependent on overseas computing for sensitive data processing.
A spokesman said: “It would be a disaster for jobs and national security.”
There are hundreds of data centres in the UK – with plans for many more.
Exact numbers are hard to find, but the BBC reported last year there were around 477.
Many are clustered around London and the south of England – areas which are officially in drought at the moment.
The amount of water data centres consume can change based on size, design and local climate – the hotter the area the more water needed to cool the equipment.
Speaking on a visit to the site of a proposed data centre in East London, Polanski told the BBC: “We need to slam the brakes on these energy guzzling, water guzzling data centres.
“Essentially, we need basically a moratorium other than local scale data centres for the local community.
“At a time when three-quarters of the country are in drought, it is outrageous that these are being considered critical infrastructure.
“To most people critical infrastructure means hospitals, water, electricity. It doesn’t mean Artificial Intelligence.”
Data centres were classified as critical in 2024, meaning they get extra government support during incidents like cyber-attacks or extreme weather.
The Greens argue this means they could get priority over households for water. The government said data centres would not automatically get priority during shortages.
The BBC has also discovered that ministers have not carried out an environmental assessment on the impact of their “Delivering AI growth zones strategy, external“.
A government official said it sees the paper as a statement of intent, rather than a formal policy moving towards implementation.
Data centres in the UK do not currently have to report the amount of water they use.
