Summary
- Defra says water companies are not required to provide water for data centre cooling.
- A connection may be refused where sufficient water resources are unavailable.
- National data centre consumption remains small, while local and peak-demand effects can be materially different.
Water companies are not required to supply water for data centre cooling and can refuse a connection where sufficient local resources are unavailable, the UK government has confirmed.
The Department for Environment, Food and Rural Affairs set out the position in a parliamentary answer on the potential effect of proposed AI-capable data centres in Essex.
It said data centre water use is expected to remain below 1% of national water demand, but warned that local effects may be significant, particularly during periods of peak demand.
The distinction gives developers a clearer indication that a relatively small national share does not guarantee supply at an individual site.
Local networks determine whether water is available
Water infrastructure is constrained at catchment, treatment, and distribution level rather than by a single national total.
A separate parliamentary answer published on 16 September cited a 2025 techUK and Environment Agency survey in which 51% of surveyed data centre sites used closed-loop cooling and 64% consumed less than 10,000m³ of water annually.
Data centres in England were estimated to account for around 0.2% of non-household water use.
Those figures provide context for the current installed estate, but they do not determine the effect of a large proposed development in a specific water-stressed location.
Peak conditions create a further issue because periods of higher cooling demand can coincide with hot weather when wider water consumption and environmental pressure on supplies are also elevated.
DataCentral previously examined the distinction between national averages and local peak-demand constraints. The latest Defra answer adds a practical consequence: the water company can refuse a cooling connection if the resource is not available.
Cooling design changes the exposure
The amount of water consumed by a data centre varies considerably according to its cooling architecture, climate, operating temperatures, utilisation, and heat-rejection system.
Closed-loop liquid cooling inside the data hall does not necessarily mean a facility has no external water demand. Heat collected from servers still has to be rejected from the building.
Evaporative systems can consume water during that process, while dry cooling can reduce direct consumption but introduce different energy, space, and high-temperature performance trade-offs.
The government said it supports efficient closed-loop systems and alternative supplies such as rainwater harvesting, and expects developers to work with water companies to establish sustainable supply arrangements.
Defra’s Water Delivery Taskforce is also working with regulators and the industry to improve the evidence base around data centre consumption.
For development teams, the consequence is to test water assumptions during site selection and cooling design rather than after planning and power strategy have already been fixed.
A site can have land and electrical capacity and still face a delivery constraint if its cooling design depends on a water connection the local utility cannot support.
