Scotland’s data centre reckoning part 3: The water nobody accounted for

SCOTLAND IS A WET COUNTRY. That is the perception – the hills, the lochs, the rain that defines the national climate and the national character in equal measure. It is also, for most purposes, broadly accurate. Scotland has more fresh water per head of population than almost any country in Europe.

It is therefore startling to learn that SEPA – the Scottish Environment Protection Agency – confirmed in May 2025 that every part of Scotland was experiencing some level of water scarcity. This does not mean drought, in the catastrophic southern European sense. Rather it refers to the measurable, documented, ecologically significant water stress, affecting river flows, reservoir levels, and the abstraction licences that govern who is permitted to take water from Scottish catchments and how much.

It is more startling still to learn that no hyperscale data centre planning application in Scotland has been required to declare its true water demand before consent is granted – or to demonstrate that the water it proposes to use is actually available.

The cooling problem

Data centres generate enormous quantities of heat. Every megawatt of electricity consumed by the servers inside them produces approximately one megawatt of heat that must be removed or the equipment fails. Cooling is not optional. It is the fundamental engineering constraint that shapes every large data centre design.

There are two primary cooling approaches. Closed-loop systems circulate water or air through a sealed system, extracting heat without consuming significant quantities of water. Evaporative cooling systems – wet cooling towers – remove heat by evaporating large quantities of water into the atmosphere. The water consumed is gone. It does not return to the catchment it was drawn from.

The water consumption difference between these two approaches is not marginal. A 500 megawatt facility using evaporative cooling, operating at 80 per cent utilisation year-round with an industry-standard Water Usage Effectiveness ratio of 1.8 litres per kilowatt-hour of IT load, draws approximately 17 to 19 million litres per day from the water supply system.

To put that figure in terms that planning committees and local residents can understand: 19 million litres per day is the daily water consumption of a city the size of Perth. It requires a dedicated 450 to 600 millimetre mains connection, maintained at sustained industrial pressure, continuous and uninterrupted. Scotland’s existing water distribution infrastructure was not designed to accommodate this demand. In most of the areas where data centres are being proposed, it physically cannot.

What is happening in Fife

The proposed Auchtertool data centre in Fife illustrates the gap between what developers declare and what their cooling systems would actually consume.

The developer declared a water demand of 93,000 litres per day in their planning submission. Scottish Water reviewed the application and confirmed that the existing mains pipe serving the area was too small to meet even that declared figure – let alone the 17 to 19 million litres per day that the facility would actually require if it used evaporative cooling.

A figure of 93,000 litres per day is consistent with one thing only: a fully closed-loop cooling system that consumes almost no water. If that is what is being built, it should be a binding condition of consent – not an unstated assumption buried in a planning statement that the developer is free to revisit once permission is granted.

The catchment conditions make the stakes of this ambiguity clear. Lomond Hills reservoirs – the primary drinking water source for Fife – stood at 21 per cent of combined capacity in 2025, the lowest level recorded in thirty years. The River Eden catchment has had abstraction licences suspended by SEPA under its Significant Scarcity designation in both 2022 and 2025. These are not theoretical future risks. They are documented, recurring, current conditions in the catchment from which any Fife data centre would draw its water.

Adding 17 to 19 million litres of daily evaporative cooling demand to a catchment already at its environmental limit is not a planning risk to be assessed and mitigated. It is a planning harm that cannot be consented under the Water Framework Directive’s environmental flow requirements.

The licensing gap

Scotland’s water abstraction regime is governed by the Environmental Authorisation (Scotland) Regulations 2018. Under EASR, any abstraction exceeding 50 cubic metres per day requires a Complex Licence from SEPA. A 500 megawatt facility using evaporative cooling would require authorisation for abstraction of approximately 17,000 times that threshold.

SEPA cannot grant a Complex Licence for abstraction that would breach environmental flow requirements or exacerbate a Significant Scarcity designation. In Fife catchments, on current evidence, it would have to refuse – or impose conditions that make evaporative cooling operationally impossible.

The problem is sequencing. Under current practice, SEPA authorisation is sought after planning consent is granted, not before. A developer can receive planning permission for a facility whose water demand would be refused by SEPA, then spend months or years in litigation over the authorisation, while the community that objected to the planning application has no further standing.

What responsible consent looks like

Every applicant should be required to submit a Water Usage Effectiveness declaration using Green Grid standard methodology, independently verified, specifying the cooling technology, the WUE target in litres per kilowatt-hour of IT load, and the resulting maximum daily and annual abstraction volume. This is standard practice in jurisdictions that have thought carefully about data centre development – Denmark, Singapore, and the state of Virginia among them.

Scotland has not required it. Scotland has allowed developers to declare water demands that bear no relationship to what their cooling systems would actually consume, to receive planning consent on that basis, and to proceed toward construction without SEPA having confirmed that the water is available.

The prohibition on evaporative cooling in water-stressed catchments is not a preference. It is a response to documented conditions. The Lomond Hills reservoir levels, the Eden Significant Scarcity designation, the Scottish Water infrastructure gap – these are not projections. They are facts on the public record, available to any planning reporter who looks for them.

The question is not whether evaporative cooling is problematic in Fife. It is why the planning system has not yet said so.