Why do data centers use so much water?

Why do data centers use so much water?

Because the electricity a data center uses ends up as heat, and evaporating water is the most energy-efficient way to get rid of it. Servers and storage systems give off heat as a by-product of their work[6], and keeping them cool can take as much as 40% of a data center’s energy[7]. That is why most big modern facilities cool by evaporation, especially in hot climates, even though the method consumes water directly[4]. The Congressional Research Service puts the trade-off plainly: evaporation-based systems generally use less energy than air-cooled chillers and other waterless designs, which save the water but spend more power[8].

Evaporation is also why the water doesn’t come back. In a cooling tower, heat leaves the building as water vapor[9]. The Environmental Law Institute estimates that evaporative systems lose about 80% of the water they draw and discharge the other 20%[3]. The U.S. Geological Survey calls that consumptive use: water that is no longer available to the local supply, rather than water borrowed and returned[10].

Three things decide how much a particular site uses: its size, how densely it packs computing, and the kind of cooling it runs[5]. Density is rising fast. An industry executive quoted by IEEE Spectrum put the average rack at around 8 kilowatts, and AI racks at up to 100[11]. More power in the same room means more heat to remove, which is pushing AI campuses toward liquid cooling that works right at the chip[12].

The largest share of a data center’s water footprint isn’t on site at all. The power plants that make its electricity need water too[13]: about 211 billion gallons in 2023 by one federal estimate[2], roughly 12 times the 17 billion gallons data centers used directly that year[1].

Some operators are choosing the other side of the trade. Microsoft says its zero-water-for-cooling design will save more than 125 million liters of water per data center each year[14], at the cost of a higher PUE and what it calls a nominal increase in annual energy use[14]. The Environmental and Energy Study Institute sums up the choice: where water is scarce, liquid cooling of servers fits best; where the power grid is strained, evaporative towers make more sense because they need little electricity[2].

Do AI data centers use a lot of water?

They can, because AI packs far more heat into each rack: about 8 kilowatts for an average rack against up to 100 for AI, according to an industry executive quoted by IEEE Spectrum[11]. How much water a site uses depends on its size, its computing density and its cooling system[5], and the densest AI hardware is pushing cooling toward liquid systems that work right at the chip[12]. Many of those run as closed loops, which keep water circulating in a sealed system instead of evaporating it[8]; Meta says its closed-loop, direct-to-chip sites use no water in the cooling system during operation[15] (a company claim).

The electricity is the bigger water story. Generating the power U.S. data centers used in 2023 consumed roughly 211 billion gallons[2], about 12 times the 17 billion used on site[1], so an AI campus’s power draw matters as much as its cooling design. Company totals are rising: Google says its water consumption grew 34% from 2024 to 2025[16], and Microsoft’s roughly doubled between fiscal 2020 and 2025[17], both company-reported.

How much water does one data center use?

It varies enormously. Virginia's JLARC found most data centers use about as much water as an average large office building or less, though a few use substantially more and some use less than a typical household[5]. The amount depends on the facility's size, computing density and type of cooling[5]. At the high end, larger data centers can use up to 5 million gallons a day, according to reporting cited by the Environmental and Energy Study Institute[2].

Local examples show why it can matter. Google's facilities in The Dalles, Oregon, used 355.1 million gallons in 2021, and the company accounted for 29% of the city's water use, according to reporting cited by DatacenterDynamics[18]. Microsoft's West Des Moines, Iowa, data centers used up to 11.5 million gallons a month for cooling, about 6% of the city's peak-summer usage, Axios reported[19].

How do data centers use water?

Mostly for cooling. In a common design, a condenser water loop carries heat to a cooling tower, where evaporation removes it to the atmosphere[9]. The Environmental Law Institute says evaporative cooling loses about 80% of the water it draws to evaporation and discharges the other 20%[3]. LBNL notes that cooling-tower evaporation is behind local concerns about data center water use[20].

Other designs use much less. Air cooling can need little water when outside air is cold, though it may still use cooling towers[3]. Direct-to-chip liquid cooling pumps water or a glycol mix through channels on the chips in a closed loop to a chiller[3]. Meta says its closed-loop, dry-cooled sites use no water to run their cooling systems[15], and Microsoft says its zero-water-for-cooling design recirculates water filled once during construction[14]. These are company claims.

Data centers also use water indirectly through the power plants that supply them. A peer-reviewed 2021 study found nearly half of U.S. data center servers are fully or partly powered by plants in water-stressed regions[13].

Withdrawal vs. consumption

Two terms get mixed up. The U.S. Geological Survey defines withdrawal as “Water removed from the ground or diverted from a surface-water source for use”[10], and consumptive use as the part that evaporates or is otherwise not available for immediate reuse[10]. Evaporative cooling is consumptive. The industry metric, Water Usage Effectiveness (WUE), is annual water use divided by IT energy, in liters per kilowatt-hour[21], and includes cooling-tower evaporation[21].

Do data centers recycle water?

Some do, in two ways. Closed-loop cooling recirculates the same water instead of evaporating it (see above). Others use reclaimed wastewater: Loudoun Water in Virginia built its reclaimed water system beginning in 2010 to supply industrial cooling water to data centers, and it now spans 20 miles of pipeline[22], delivering more than 750 million gallons of reclaimed water in 2025[22]. Google says its Douglas County, Georgia, data centers began cooling servers with recycled water in 2012[23].

Recycling has limits. The Environmental Law Institute notes that reclaimed water used this way is not returned to the local watershed[3], and evaporative systems still lose most of the water they draw[3].

What the biggest companies report

• Google: 10.9 billion gallons across data centers and offices in 2025, up 34% from 2024[16].
• Microsoft: 8,170 megaliters company-wide in fiscal 2025, up from 3,990 in FY20[17].
• Meta: 2,974 megaliters at its data centers in 2024[24].

All company-reported.

Water figures, project by project

Of 186 tracked projects, 45 have a published water-use figure and 111 disclose something about water or cooling. Many figures are permit limits or estimates; open a project for the source and notes.

“Not published” means no figure was found in the sources reviewed. Convert any figure into household terms.

Common questions

Why do data centers use so much water?

Mostly to cool their servers. Computing turns electricity into heat, and evaporating water in cooling towers is the most energy-efficient way to remove it at scale, but the water that evaporates is used up: the Environmental Law Institute estimates about 80% of the water drawn is lost this way. Denser AI computing adds more heat per rack.

Why do data centers need water?

To reject heat. Evaporative cooling is generally more energy efficient than waterless systems, so many large data centers use it. They also use water indirectly through the power plants that make their electricity: about 211 billion gallons in 2023, versus about 17 billion gallons used directly.

How much water do data centers use?

U.S. data centers directly used about 17 billion gallons of water in 2023, according to an estimate cited by the Congressional Research Service, and about 211 billion gallons indirectly through electricity generation. The largest individual data centers can use up to 5 million gallons a day.

How do data centers use water?

Mainly for cooling. In evaporative cooling, water carries heat to a cooling tower and evaporates; the Environmental Law Institute says evaporation takes about 80% of the water drawn. Air-cooled and closed-loop liquid designs use much less.

Do data centers recycle water?

Some do. Closed-loop systems recirculate water, and some data centers use reclaimed wastewater, such as the Loudoun Water system in Virginia. Evaporative cooling still loses most of the water it draws.

Do AI data centers use a lot of water?

They can, because AI racks run far hotter than ordinary ones, but many new AI campuses use closed-loop liquid or air cooling that needs little water on site. The larger share is indirect: power plants supplying U.S. data centers consumed about 211 billion gallons in 2023, versus about 17 billion used directly.

Do data centers use more water than homes?

Most use about as much as a large office building or less, according to Virginia’s JLARC, but a few use substantially more, and the largest can use up to 5 million gallons a day.

Sources

1. DATA CENTERS AND WATER: What Congress found
   Western Water · 2026-08-07
   Source excerpt

   “One study cited by the Congressional Research Service estimated that U.S. data centers directly used approximately 17 billion gallons of water in 2023. That compares with about 5.6 billion gallons in 2014.”

2. Data Centers and Water Consumption
   Environmental and Energy Study Institute (EESI) · 2025-06-25
   3 source excerpts

   “A federal report estimated that the indirect water consumption footprint (from electricity use) of data centers in the United States was roughly 211 billion gallons in 2023.”

   “In areas with limited water availability, server liquid cooling is the best choice, as it requires minimal water consumption. Conversely, in areas with a strained power grid, an evaporative air cooling tower is a suitable building design, as it requires minimal power usage.”

   “Larger data centers can each 'drink' up to 5 million gallons per day, or about 1.8 billion annually, usage equivalent to a town of 10,000 to 50,000 people.”

3. Data Centers and Water Fact Sheet
   Environmental Law Institute · 2026-01
   5 source excerpts

   “Combines air cooling with open-loop water evaporation to cool air in the data center. Approximately 80% of water drawn is lost to evaporation and 20% is discharged.”

   “U.S. data centers directly consumed approximately 21.2 billion liters of water in 2014 and 66 billion liters in 2023.”

   “Air conditioning, fans, and vents used to expel hot air and intake cool air. This can have low water requirements if ambient air temperature is cold (e.g. 'free' cooling), or may require cooling towers.”

   “Liquid is pumped through microchannels directly on the chips surface to absorb heat. Most commonly use pure water or a glycol mix of liquid and run in a closed-loop system to a chiller.”

   “Data centers that use reclaimed water will often treat the water themselves on-site and have a water storage system, reducing their peak demand impact on a water utility. But even when facilities use reclaimed water, that water is not being returned to the local watershed where it is needed.”

4. Understanding How Data Centers Impact Surface and Ground Waters
   University of Georgia College of Agricultural & Environmental Sciences (UGA Extension) · 2026-06-10
   Source excerpt

   “A majority of large modern data centers use evaporative cooling because it is energy-efficient, especially in hot climates. The downside is that it directly consumes water.”

5. Data Centers in Virginia (Report 598)
   Joint Legislative Audit and Review Commission, Virginia General Assembly · 2024-12-09
   2 source excerpts

   “The amount of water a data center uses depends on its size, computing density, and type of cooling system.”

   “Most data centers use about the same amount of water or less as an average large office building, although a few require substantially more, and some require less than a typical household.”

6. High-Performance Computing Data Center Cooling System Energy Efficiency
   National Renewable Energy Laboratory (nrel.gov) · 2025-04-10
   Source excerpt

   “IT equipment, such as compute clusters and data storage systems, produces heat as a byproduct.”

7. DOE Announces $40 Million for More Efficient Cooling for Data Centers
   U.S. Department of Energy · 2023-05-09
   Source excerpt

   “data center cooling can account for up to 40% of data center energy usage overall”

8. Data Centers and Water: Frequently Asked Questions (R49057)
   Congressional Research Service (via EveryCRSReport.com) · 2026-07-31
   2 source excerpts

   “Trade-offs in water consumed and power usage exist between evaporation-based cooling systems and air-cooled systems. Evaporation-based cooling systems are generally more energy efficient than air-cooled chillers or other waterless systems. While air-cooled chillers use no water, they use comparatively more energy.”

   “Closed-loop cooling systems, which circulate water within a sealed system without direct exposure to the environment, may generate more limited wastewater discharges during normal operational phases.”

9. Cooling Water Efficiency Opportunities for Federal Data Centers
   U.S. Department of Energy, Federal Energy Management Program · 2019-01-09
   Source excerpt

   “The condenser water loop carries the heat to the cooling tower where the evaporative process extracts the heat and dissipates it to the surrounding atmosphere.”

10. Water Use Terminology
    U.S. Geological Survey
    2 source excerpts

    “The part of water withdrawn that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise not available for immediate use.”

    “Water removed from the ground or diverted from a surface-water source for use.”

11. Next-Gen AI Needs Liquid Cooling
    IEEE Spectrum · 2025-10-13
    Source excerpt

    “The average power density in a rack was around 8 kW … For AI, that's growing to 100 kW per rack. That's an order of magnitude.”

12. Data Centers and Their Energy Consumption: Frequently Asked Questions (R48646)
    Congressional Research Service · 2025-08-26
    Source excerpt

    “High-performance computing (HPC) equipment has necessitated cooling methods that are thermodynamically closer to the chips and intercept the energy before it has substantially raised the room air temperature. These direct liquid cooling technologies can address the higher power of HPC.”

13. The environmental footprint of data centers in the United States
    Lawrence Berkeley National Laboratory (Environmental Research Letters) · 2021-05
    2 source excerpts

    “Large amounts of water are also required to operate data centers, both directly for liquid cooling and indirectly to produce electricity. ... Our bottom-up approach reveals one-fifth of data center servers direct water footprint comes from moderately to highly water stressed watersheds”

    “nearly half of servers are fully or partially powered by power plants located within water stressed regions.”

14. Sustainable by design: Next-generation datacenters consume zero water for cooling
    Microsoft · 2024-12-09
    3 source excerpts

    “this design will avoid the need for more than 125 million liters of water per year per datacenter.”

    “Replacement of evaporative systems with mechanical cooling will increase our power usage effectiveness (PUE). … The result is a nominal increase in our annual energy usage compared to our evaporative datacenter designs across the global fleet.”

    “These new liquid cooling technologies recycle water through a closed loop. Once the system is filled during construction, it will continually circulate water between the servers and chillers to dissipate heat without requiring a fresh water supply.”

15. Advancing Water Stewardship in Our Data Center Communities
    Meta · 2025-12-17
    Source excerpt

    “For these data centers, there is no operational water use in the cooling system and water use at the site is minimal and limited to domestic and janitorial needs, equipment cleaning, and fire protection.”

16. Google 2026 Environmental Report
    Google · 2026-06
    2 source excerpts

    “Our water consumption increased 34% from 2024 to 2025 as we continued to meet the world's increasing demand for digital services.”

    “In 2025, we consumed 10.9 billion gallons (41 billion liters or 41 million cubic meters) of water across our data centers and offices.”

17. 2026 Environmental Sustainability Report Data Fact Sheet
    Microsoft · 2026
    Source excerpt

    “Table 8 – Water and effluents (ML) ... Total water consumption 3,990 4,794 5,329 5,818 6,693 8,170”

18. We now know how much water Google's Oregon data centers use, after city drops lawsuit against journalists
    DatacenterDynamics · 2022-12-19
    Source excerpt

    “In 2021, the company's facilities consumed 355.1 million gallons of water, The Oregonian/OregonLive reports. ... He said that the city's overall water use has doubled from 2002 to 2021 ... Google accounts for 29 percent of the city's total consumption.”

19. Microsoft's AI epicenter is an Iowa water hog
    Axios Des Moines · 2023-09-18
    Source excerpt

    “consumed as much as 11.5 million gallons of water a month for cooling, or about 6% of WDM's total usage during peak summer usage during the last two years.”

20. 2024 United States Data Center Energy Usage Report
    Lawrence Berkeley National Laboratory · 2024-12-20
    Source excerpt

    “The water evaporation process in cooling towers has raised concerns regarding data center water consumption and availability at the local level.”

21. Water Usage Effectiveness (WUE): A Green Grid Data Center Sustainability Metric (White Paper #35)
    The Green Grid · 2011
    2 source excerpts

    “The metric for water usage in the data center is defined at a high level as: Annual Water Usage / IT Equipment Energy ... The units of WUE are liters/kilowatt-hour (L/kWh).”

    “Water consumed for cooling the data center or data center–associated power-generating equipment (including cooling tower evaporation, blowdown, and drift)”

22. Reclaimed Water Program
    Loudoun Water · 2026
    2 source excerpts

    “In 2010 Loudoun Water constructed the first pipelines of the reclaimed water distribution system to supply irrigation and industrial cooling water to Loudoun County's rapidly growing data center industry. The reclaimed water distribution system has since expanded to 20 miles of pipeline.”

    “In 2025, Loudoun Water delivered more than 750 million gallons of reclaimed water to customers, helping to save an equal amount of potable drinking water.”

23. Douglas County, Georgia - Google Data Centers
    Google · 2026
    Source excerpt

    “our facilities in the region are among the first in the industry to use recycled industrial water to cool our servers.”

24. Meta 2025 Environmental Data Index
    Meta · 2025-10
    Source excerpt

    “Water Consumption (in megaliters) ... Data centers total 2,197 162 2,511 2,938 2,974”

Each source was opened and checked against the excerpt shown. Company statements are identified as such. Figures are as published; where sources differ, each is shown.