Data Centre Futures: Water - Strategic design for water-conscious data centres (Issue 01)

Overview

This report is the first issue of Arup's foresight series (Arup Foresight), dated 2025. It examines the energy-versus-water trade-off in data centre heat rejection and how growing hyperscale capacity concentrates water stress regionally. The content covers global consumption projections, WUE targets from industry pacts and national roadmaps, and worked examples.

The report's basic observation is that air-only heat rejection uses more electricity and less water, while adiabatic and evaporative systems use less electricity and more water. In the IEA base case, data centre water consumption is about 560 billion litres a year, projected to reach about 1,200 billion litres by 2030. About 22% of data centres use liquid cooling, and cooling is roughly 20% of capex and 50% of opex.

Targets and examples are also presented. The Climate Neutral Data Centre Pact targets cutting WUE from today's average of about 1.8 L/kWh to 0.4 L/kWh in water-stressed locations by 2040. In Singapore's roadmap, cooling towers account for up to 97% of data centre water use, and the target is to lower WUE from 2.2 to 2.0 m3/MWh or lower within 10 years. At Equinix PA10, heat pumps lift 28 C server exhaust to 65 C, delivering up to 6.6 MWth (about 10 GWh a year) to a district network.

Meta's planned Spanish site cut annual water use by nearly 80% using dry cooling and higher server room temperatures. An Arup expert piece covers siting, upstream and downstream water impacts and moving away from freshwater. The report closes by recommending that PUE and WUE be balanced by location rather than optimising either alone. As a limit, it is a consultancy foresight document and not a standard, and the figures depend on their sources.

Key points

1. Air-only heat rejection uses more electricity and less water; adiabatic/evaporative systems use less electricity and more water.
2. IEA base case: data centre water consumption about 560 billion litres/yr, projected to reach about 1,200 billion litres by 2030.
3. About 22% of data centres use liquid cooling; cooling is roughly 20% of capex and 50% of opex.
4. Climate Neutral Data Centre Pact target: cut WUE from today's ~1.8 L/kWh average to 0.4 L/kWh in water-stressed locations by 2040.
5. Singapore roadmap: cooling towers account for up to 97% of DC water use; target WUE from 2.2 to 2.0 m3/MWh or lower within 10 years.
6. Equinix PA10: 28 C server exhaust lifted to 65 C by heat pumps, up to 6.6 MWth (~10 GWh/yr) to a district network.
7. Meta's planned Spanish site cut annual water use by nearly 80% using dry cooling and higher server room temperatures.
8. PUE and WUE should be balanced by location rather than optimising either alone.

Using it in design

• Show WUE (L/kWh) next to PUE for every heat-rejection option.
• Warn when an evaporative design is placed in a water-stressed location.
• Seed default WUE targets (for example 0.4 L/kWh for stressed sites).
• Allow a dry-cooler-only scenario for comparison.

Who should read it

Cooling and sustainability designers, planners selecting sites and decision makers weighing water risk alongside PUE.

Related standards

• ISO/IEC 30134-9 (WUE)
• Climate Neutral Data Centre Pact

Publication details

Authors

Arup

Publisher

Arup (Arup Foresight)

Year

2025

Document number

Issue 01

Document language

English

Source type

Expert / community

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation