Data centers use water mainly to remove heat from servers. In an evaporative system, water carries heat away as it evaporates; air-cooled and closed-loop liquid systems can require little or no ongoing cooling water. The amount a proposed facility will use therefore depends on its cooling design, climate, operating load, water source, and the boundary used in its reports—not simply on the fact that it is a data center.
Residents evaluating a project should ask for absolute withdrawals and consumption, peak and seasonal demand, the source of every water input, the cooling system actually being installed, discharge plans, and the definition behind any water-usage metric. A low water-intensity number can coexist with a large total demand or serious local impacts.
As an Amazon Associate I earn from qualifying purchases.
Where water enters a data center
Servers convert electricity into heat. A cooling system transfers that heat from server rooms to a heat-rejection system and then to outdoor air or another sink. Water can be involved at several points:
- Evaporative heat rejection: Cooling towers or other evaporative equipment release heat by turning part of the water into vapor. That evaporated portion is locally consumed rather than returned immediately to the supply.
- Humidification: Some facilities add moisture to indoor air to keep conditions within equipment specifications.
- Initial fills and maintenance: A system may need a substantial first fill, periodic flushing, treatment, and top-ups. A reported annual operating figure may or may not include these items.
- Related equipment: Backup-power systems, water treatment, and other site operations can have water requirements. Ask the operator whether these are inside the reported boundary.
Water that is not evaporated can become a concentrated blowdown stream and require treatment or discharge under a permit. The temperature, chemistry, destination, and volume of that discharge matter as much as the intake number.
Cooling designs have very different water profiles
The label “data center” does not identify a single cooling technology. Ask which design is operating now, not just which design appeared in an early planning document.
| Design approach | How heat is rejected | What residents should expect | Questions to ask |
|---|---|---|---|
| Evaporative cooling | Water evaporation removes heat, often through cooling towers. | Ongoing consumption can be significant and can rise during hot or dry periods. | What are annual and peak-day withdrawals and evaporation losses? How is blowdown treated? |
| Air-side or dry cooling | Fans and heat exchangers reject heat directly to outdoor air. | Little or no ongoing cooling-water demand, but electricity use and performance can vary with weather. | Is the system fully dry at the planned load, or is water used during hot-weather events? |
| Closed-loop liquid cooling | Liquid circulates through equipment and a heat exchanger; the loop is not continually replaced. | Routine demand may be low after the initial fill, with water still needed for maintenance or heat rejection elsewhere. | What is the initial fill volume, makeup requirement, and heat-rejection method outside the loop? |
| Hybrid systems | Switches between dry and evaporative modes according to temperature, load, or water availability. | Water use is conditional; the highest demand may occur during the same hot, dry periods when supplies are tight. | What trigger changes modes, and what is the modeled demand under extreme heat and drought? |
The European Commission describes material variation by technology and country in its 2026 communication. Its EU figure should not be treated as a design specification for a particular site. Read the European Commission communication.
How much water do data centers actually use?
Operators should report both withdrawals (water taken from a source) and consumption (water not returned promptly to that source, commonly through evaporation). A facility can withdraw a large volume but consume less if much of the water is discharged; conversely, evaporative consumption can directly reduce water available locally.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsWUE is an intensity metric
Water usage effectiveness, or WUE, is generally calculated as liters of water used for cooling and humidification divided by kilowatt-hours of IT energy. It allows comparison of water intensity, but it is not a complete impact measure. It does not by itself show the facility’s total size, local scarcity, seasonal peak, source quality, discharge, or water used offsite to generate electricity. Always request the numerator, denominator, reporting period, and facility boundary.
Published figures with explicit limits
| Figure | Scope and date | How to interpret it |
|---|---|---|
| 0.58 m³/MWh (equivalent to 0.58 L/kWh) | European Commission weighted-average WUE for 2024, based on 458 EU facilities with reliable nonzero-water reports. | The population excludes facilities reporting zero consumption, including dry-cooling sites. It is an EU reporting-period statistic, not a universal benchmark. |
| 0.27 L/kWh | Microsoft’s FY25 global WUE for datacenters fully owned and controlled by Microsoft and operational for 12 months when calculated; FY25 ran from July 1, 2024, through June 30, 2025. | This is a company-reported result for a defined portfolio and methodology, not a promise that a separate project will achieve the same value. |
| No single universal value | UC Berkeley’s Center for Law, Energy & the Environment California report, February 2026. | The report emphasizes gaps in site-level data and recommends transparent, site-specific reporting rather than one statewide number. |
Sources: European Commission, Microsoft methodology, and UC Berkeley CLEE.
What to request from a proposed or operating site
Ask for numbers in gallons or cubic meters as well as WUE. A useful submission separates estimates from measured actuals and identifies the period covered.
Rank #3
- Annual and peak demand: Request projected and actual withdrawals and consumption, peak-day demand, monthly or seasonal patterns, and assumptions about server load and weather.
- Water sources: Identify potable utility water, reclaimed or recycled water, non-potable supplies, groundwater, surface water, and purchased water. Ask who holds the relevant water rights or supply agreement.
- Complete accounting: Confirm whether totals include construction, initial system fills, humidification, cooling-tower makeup and blowdown, backup power, treatment, and maintenance top-offs.
- Cooling boundary: Obtain the cooling technology, equipment capacity, operating modes, and any changes from the original proposal. A late switch from dry to evaporative operation can materially change demand.
- WUE method: Ask which IT-energy denominator is used, which facilities are included, whether the value is measured or modeled, and whether it covers only cooling and humidification.
- Discharge: Request the destination, volume, temperature, chemistry, treatment process, and permit for any discharge.
- Offsite water: Ask whether the assessment discusses water used to produce the electricity supplying the facility. That indirect use is separate from the site’s reported WUE.
How to verify the numbers in local records
- Start with the land-use filing. Look for the site plan, utility-capacity letter, environmental review, and original water-demand estimate. Note the date and whether the document describes construction, a first phase, or the fully built campus.
- Check utility and water-rights records. Confirm the contracted source, maximum connection, well or surface-water authorization, and any conditions on seasonal use.
- Read discharge permits. Compare permitted flow and temperature with the operator’s stated blowdown and wastewater plan. A permit can reveal treatment or receiving-water constraints not visible in a marketing summary.
- Compare design revisions. Request the current mechanical design and a change log. Cooling, electrical capacity, and backup-power plans can change after approval.
- Separate forecast from performance. For an operating site, seek meter readings, invoices, monthly withdrawals, and independently verified or audited reports. For a new site, label every number as an estimate and ask for sensitivity cases.
- Put demand beside supply. Compare the project’s seasonal requirement with drought restrictions, reservoir or aquifer conditions, existing household, agricultural, and industrial commitments, and other planned developments.
UC Berkeley CLEE’s February 2026 analysis of California finds that site-level information is often incomplete. Its recommendations support transparent reporting that is specific about location, source, season, technology, and measurement rather than relying on a single intensity statistic.
Utah’s disclosure rule illustrates why jurisdiction matters
There is no single nationwide data-center water disclosure system. Utah provides one current example. Its law, effective July 1, 2026, covers specified new projects larger than 10,000 square feet that intend to draw at least 75 acre-feet annually.
For qualifying projects, preconstruction reports include the location, estimated withdrawals, applicable discharge plans and temperature adjustment, and water-reuse or replacement efforts. Annual reports include actual withdrawals and related efforts. The state says public annual reports are to be posted by September 1, subject to stated confidentiality exceptions. Large centers already operating or under construction before the effective date are excluded. Details and applicability should be checked with the Utah Division of Water Rights; this Utah rule is not a national requirement.
Water efficiency can shift energy use
Dry and closed-loop approaches can reduce direct water consumption, but they are not automatically impact-free. UC Berkeley CLEE notes that more water-efficient cooling strategies usually use more energy, with the tradeoff changing by scale and location. Extra electricity can increase operating cost and the water used at power plants, while evaporative cooling can reduce electricity for heat rejection but draw on local water supplies.
Ask for both sides of that tradeoff: annual electricity use, peak power, the grid or generation assumptions, direct water withdrawals and consumption, and any estimate of offsite water associated with electricity. A proposal that presents only WUE omits this essential context.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →How to compare two projects or designs fairly
Use the same questions and units for every option. A comparison is meaningful only when the reporting boundaries and time periods match.
| Comparison axis | Evidence to place side by side |
|---|---|
| Absolute water | Annual withdrawals, annual consumption, peak-day volume, and seasonal maximum under the same IT-load scenario. |
| Source and scarcity | Potable, reclaimed, non-potable, groundwater, or surface water; local availability and drought conditions. |
| Cooling boundary | Technology, operating modes, initial fills, maintenance makeup, and equipment included. |
| WUE | Value, numerator, IT-energy denominator, period, facilities covered, and whether measured or estimated. |
| Energy and indirect water | Electricity consumption and peak demand, plus any quantified water used in electricity generation. |
| Discharge | Volume, temperature, quality, treatment, receiving system, and permit conditions. |
| Transparency | Metered or modeled figures, independent assurance, publication frequency, and confidentiality limits. |
Project-specific operator statements can be useful but should be labeled as such. For example, Oracle’s Project Jupiter description explains that project’s planned design and water use; it is not an independent industry benchmark. Read the project statement.
Common mistakes residents can avoid
- Multiplying a WUE number by total facility electricity without checking the denominator. WUE normally uses IT energy, not necessarily the whole site’s electricity.
- Treating “zero” as proof of zero water impact. A zero-consumption report may reflect dry cooling at the site while electricity generation, construction, or another boundary uses water.
- Using a global or national average to judge one neighborhood. Local source, scarcity, season, and discharge determine the practical impact.
- Reading only annual totals. A moderate annual volume can still create a difficult summer peak that coincides with household or agricultural restrictions.
- Assuming reclaimed water eliminates all concerns. Reuse can protect potable supplies, but availability, treatment energy, replacement obligations, and competing users still need documentation.
- Accepting an early proposal after the design changes. Require updated figures whenever cooling, power capacity, phasing, or water connections change.
A resident’s decision test
A defensible assessment should let you answer six questions without guessing: What cooling system is actually being built? How many gallons or cubic meters will it withdraw and consume annually and on the peak day? Where does each input come from, and who has the right to supply it? What happens to discharge? Which figures are metered, estimated, or independently checked? How does the demand fit the community’s seasonal supply, existing commitments, and energy system?
If any answer is missing, request a revised, site-specific disclosure before drawing conclusions. The most informative comparison combines absolute water, WUE, energy, source, scarcity, discharge, and measurement quality; no single metric can substitute for that set.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
