Data Center Cooling Types and Water Use: Published WUE by System
Cooling type is the biggest reason one data center uses far more water than another. Operators who report WUE (liters of water per kilowatt-hour of IT energy) show evaporative sites around 1.35 to 1.73 and air-cooled sites between 0 and 0.07. Every figure below links to its source and page.
Evaporative cooling towers
| Figure | WUE | Source and page |
|---|---|---|
| CyrusOne 2025 operating WUE Site, nonstandard wet (water-cooled) facilities | 1.35 L/kWh | CyrusOne 2026 Sustainability Report, p. 36, 'Average Operating WUE Site (ISO WUE1) (L/kWh)' table (2018, 2024, 2025) |
| Equinix 2025 WUE at sites using evaporative cooling | 1.41 | Equinix 2025 Sustainability Report, p. 26 (unit as published: not stated in source) |
| NTT DATA FY2024 WUE, evaporative sites only | 1.42 | NTT DATA Group ESG Data: Environment Data, 'Data Center WUE' table (FY2022, FY2023, FY2024) (unit as published: l/kWh) |
| Digital Realty 2025 weighted average WUE, sites with evaporative cooling | 1.73 | Digital Realty 2025 Impact Report, p. 15, WUE table (2025, 2024, change, non-potable share) (unit as published: not stated in table (report states WUE targets in L/kWh IT)) |
Adiabatic or evaporative assist
| Figure | WUE | Source and page |
|---|---|---|
| Range LBNL says some hyperscale operators report for airside economizer with adiabatic cooling systems (higher than LBNL's own simulation) | 0.1 to 0.3 L/kWh | 2024 United States Data Center Energy Usage Report, p. 47 (PDF p. 48) |
Air-cooled and non-evaporative
| Figure | WUE | Source and page |
|---|---|---|
| LBNL statement that air-cooled chillers use no water for cooling (humidification can still use small amounts; see operator rows) | 0 L/kWh | 2024 United States Data Center Energy Usage Report, p. 45 (PDF p. 46) |
| CyrusOne 2025 operating WUE Site, standard dry (air-cooled) facilities | 0 L/kWh | CyrusOne 2026 Sustainability Report, p. 36, 'Average Operating WUE Site (ISO WUE1) (L/kWh)' table (2018, 2024, 2025) |
| CyrusOne design WUE Site for its standard dry design, humidification water only, full capacity | 0.002 L/kWh | CyrusOne 2026 Sustainability Report, p. 35 |
| Digital Realty 2025 weighted average WUE, sites with non-evaporative cooling | 0.07 | Digital Realty 2025 Impact Report, p. 15, WUE table (2025, 2024, change, non-potable share) (unit as published: not stated in table (report states WUE targets in L/kWh IT)) |
All U.S. data centers (LBNL model)
| Figure | WUE | Source and page |
|---|---|---|
| LBNL modeled annual average site WUE across all US data centers through 2023 (published as 'just over 0.36') | 0.36 L/kWh | 2024 United States Data Center Energy Usage Report, p. 48 (PDF p. 49), Figure 4.7 text |
| LBNL projected US average site WUE after 2023 (scenario range to 2028) | 0.45 to 0.48 L/kWh | 2024 United States Data Center Energy Usage Report, p. 48 (PDF p. 49) |
| LBNL modeled aggregate median site WUE for the hyperscale category (2023 cooling mix); LBNL notes it would be 0.40 if adiabatic systems ran at a 0.2 L/kWh median | 0.32 L/kWh | 2024 United States Data Center Energy Usage Report, p. 47 (PDF p. 48) |
- On-site water use effectiveness published by LBNL and by CyrusOne, Equinix, NTT DATA and Digital Realty, by cooling type.
- CyrusOne 2026 Sustainability Report (covers 2025), Equinix 2025 Sustainability Report, NTT DATA Group ESG Data: Environment Data
- , 12 published wue figures
How this was built
WUE, as The Green Grid defines it, is a site's yearly water use divided by its IT equipment energy. Multiply a WUE by IT energy to get on-site water. The data center water use calculator does that for you and uses the low, middle and high figures from this page.
No published tabulated on-site WUE by cooling type from LBNL 2024 or Lei et al. 2025: both present the ranges only as charts (LBNL Figure 4.4, Lei Fig. 4). Values were not digitized from the charts.
Limits of this data
- Operators report WUE for their own fleets, not for the whole industry, and define evaporative and air-cooled sites in their own way.
- Equinix and Digital Realty do not state the unit beside their figures; their reports describe WUE in liters per kWh of IT energy.
- No source publishes a numeric climate adjustment, so none is applied. LBNL describes its low values as favorable climates and its high values as hot, humid ones.
- On-site WUE excludes the water used to generate the electricity.
Sources
Frequently asked questions
Do air-cooled data centers use water?
Very little on site. LBNL says air-cooled chillers use no water for cooling, and operator reports show small amounts for humidification and maintenance, but they use more electricity, which has its own water cost at power plants.
What is WUE?
Water use effectiveness: a site's yearly water use divided by the energy its IT equipment uses, in liters per kilowatt-hour.
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Water Google reports withdrawing, consuming and discharging at each data center location, with the year, unit and report page for every figure.
- Microsoft Data Center Water Use by Region
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- Meta Data Center Water Use by Facility
Water withdrawal that Meta reports for each of its data centers in its 2025 Environmental Data Index, with the year, unit and source page.
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