How data centers use water
Data centers are buildings full of computers that run around the clock — and those computers generate heat that has to go somewhere. Many facilities use water to carry it away.
At a cooling tower, warm water from the cooling system is cooled by evaporating water into the surrounding air; some water is also drained off as "blowdown."[1] Evaporative, open-loop cooling is the more water-intensive approach. Closed-loop systems recirculate water and can reduce freshwater use by up to 70%.[2] There's a trade-off: Lawrence Berkeley National Laboratory notes that evaporation-based cooling is generally more energy efficient, while air-cooled chillers use no water but more energy.[3]
That's why water "consumption" matters more than water "use." Consumption is the water withdrawn minus the water discharged — generally, the water that evaporates.[2] According to EESI, approximately 80% of the water withdrawn by data centers evaporates, with the rest discharged to municipal wastewater facilities.[2]
The scale
Large data centers can consume up to 5 million gallons of water per day — equivalent to the water use of a town of 10,000 to 50,000 people. A medium-sized data center can consume roughly 110 million gallons a year for cooling, about the annual use of 1,000 households.[2]
Nationally, Lawrence Berkeley National Laboratory's 2024 report to Congress estimated that U.S. data centers directly consumed about 66 billion liters of water in 2023 (roughly 17 billion gallons), with hyperscale and colocation facilities accounting for 84% of the total. By 2028, hyperscale data centers alone are expected to consume between 60 and 124 billion liters.[3]
There's also water you don't see. Power plants use water too, so data centers carry an indirect water footprint through the electricity they draw — nearly 800 billion liters in 2023, by LBNL's estimate.[3] U.S. data centers used 4.4% of the nation's electricity in 2023, a share projected to reach 6.7% to 12% by 2028.[3]
How much water sits behind that electricity depends on how it's generated. EESI estimates that coal plants consume approximately 19,185 gallons of water per megawatt-hour, and natural gas plants approximately 2,800 gallons per megawatt-hour.[2] So a data center's total water footprint depends not only on its cooling system, but on the regional power grid it plugs into.
Why it matters regionally
Water is local. A data center draws from the same regional rivers, reservoirs and aquifers that homes, farms and businesses depend on, and water that evaporates during cooling doesn't return to that local supply.[2] Growth can be fast: EESI reports that data centers in Northern Virginia consumed close to 2 billion gallons of water in 2023, a 63% increase from 2019.[2]
Where new facilities are built matters too. In drought-prone regions, a large new water user competes with everyone else for the same supply during the hardest months. That doesn't make any single project good or bad — it makes the numbers worth knowing before decisions are made.
Siting and permitting: decisions you can follow
New data centers typically need local approvals — zoning, land use, water and wastewater service, and often state environmental permits. Those decisions usually involve public agendas, filings and meetings. You don't need to be an engineer to follow them; you need to know which questions to ask.
What residents can ask
- How much water will the facility withdraw and consume on an average day — and on the hottest days of the year?
- What cooling system will it use: evaporative, closed-loop, air-cooled or a hybrid?
- Where will the water come from — the public supply, groundwater wells or reclaimed water?
- What happens during a drought or water restriction? Does the facility have to cut back like everyone else?
- Will water use be reported publicly, and how often?
- Where will wastewater and cooling-tower blowdown go, and what will it contain?
Then check your AquaScore™ to understand the water your community already has — so you can weigh new demands on it with real data.
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Sources
- U.S. Department of Energy (FEMP). Cooling Water Efficiency Opportunities for Federal Data Centers.
- Environmental and Energy Study Institute (EESI). Data Centers and Water Consumption (June 25, 2025).
- Lawrence Berkeley National Laboratory. 2024 United States Data Center Energy Usage Report (Shehabi et al., Dec. 2024).