Data Center Water Usage: Cooling, Power Plants and Per-Day Figures

Data center water usage is one of the first things people ask about when a project is proposed near them. Answers online range from "almost none" to "millions of gallons a day". Both can be true. They describe different sites, different cooling designs and, often, different kinds of water.

This guide separates the water used on site from the water used to make the electricity. It gives the national estimates from Lawrence Berkeley National Laboratory (LBNL) and other public bodies, shows how a per-day figure is built, and ends with the questions to put to a developer. We left out any figure we could not trace to a public source.

Direct vs indirect: what counts as data center water usage?

A data center uses water in two places, and most of the disagreement online comes from mixing them up.

• Direct (site) water is used at the data center, mostly to reject heat. Cooling towers and adiabatic coolers evaporate water to carry heat away.
• Indirect (source) water is consumed at the power plants that make the electricity. LBNL notes that thermoelectric plants need significant cooling and hydroelectric reservoirs lose water to evaporation.

A second distinction matters as much. Withdrawal is water taken from a river, an aquifer or a utility. Consumption is the part that does not come back: the US Geological Survey (USGS) defines it as water that did not return to local waterbodies or groundwater, lost mainly through evaporation. A cooling tower withdraws more than it consumes, because some water is drained off as blowdown rather than evaporated.

The industry measure for site water is water usage effectiveness (WUE): site water consumption divided by IT energy, in liters per kWh. LBNL also describes a source WUE that adds the water used to generate the electricity, which is harder to calculate because it depends on where the power comes from.

How much water do US data centers use per year?

US data centers consumed about 66 billion liters of water directly in 2023, up from 21.2 billion in 2014, according to LBNL's 2024 United States Data Center Energy Usage Report. That is about 17.4 billion US gallons (our conversion).

• Who uses it. Hyperscale and colocation facilities accounted for 84% in 2023; internal (enterprise) data centers 12%, falling to 2% by 2028.
• Where it is heading. Hyperscale data centers alone are expected to consume 60 to 124 billion liters in 2028.
• Per unit of IT energy. Average site WUE stayed just over 0.36 L/kWh through 2023 and is projected to reach 0.45 to 0.48 L/kWh, partly from liquid-cooled systems.

The indirect figure is much larger: nearly 800 billion liters in 2023 (about 211 billion gallons), on roughly 176 TWh of electricity. That is 4.52 liters per kWh, close to the 4.35 L/kWh US average for all electricity. Nationally, the power plants consumed about twelve times as much water as the data centers did on site.

Two caveats. LBNL's indirect estimate assumes the local grid mix and leaves out power purchase agreements and on-site, behind-the-meter generation, which it says could change the result significantly. And these 2023 figures are the latest national water estimate we found: LBNL's 2025 update does not publish new water totals.

How much water does a data center use per day?

There is no typical figure. It depends on the site's power, cooling design, climate and season, and on whether the number counts withdrawal or consumption. Most data center water usage per day figures online come from one company's report or a calculation with no stated assumptions.

Across the whole country, LBNL's 2023 total is about 181 million liters (roughly 48 million gallons) a day. For one site, you can build an estimate from WUE. A worked example, not a real site:

1. Take 100 MW of IT load running flat out for 24 hours: 2.4 million kWh.
2. Multiply by LBNL's national average site WUE of 0.36 L/kWh: about 864,000 liters (roughly 228,000 gallons) consumed on site that day.
3. At the 0.1 to 0.3 L/kWh some hyperscale sites report for outside-air cooling with adiabatic assist: 240,000 to 720,000 liters.
4. At LBNL's 2023 average PUE of 1.4, the facility draws 3.36 million kWh. At 4.52 L/kWh, the power plants consume about 15.2 million liters (roughly 4 million gallons).

Three things move the real number. Peaks: adiabatic systems use most of their water in hot, dry weather, so a summer day can be far above the yearly average, and the peak is what the local utility must supply. Utilization: few sites run at full load around the clock. Design: dry coolers without adiabatic assist use close to no water for cooling.

People also ask how data centers compare with golf courses, farms or almond orchards. We found no like-for-like public figures to compare fairly. Locally, the better question is whether the water source can carry the extra demand in a drought year.

Why do cooling designs use such different amounts of water?

Every data center has to move its heat outdoors, and site water use comes down to whether evaporation does that job. Data center cooling systems capture heat in the hall and reject it outside; water is decided mostly on the rejection side. The common designs, as LBNL describes them:

LBNL is explicit that a low site WUE is not automatically better. Evaporative systems are generally more energy efficient. Air-cooled chillers use no water but more electricity, and more electricity means more water at the power plant. Climate sets the size of the trade-off: cool or dry places get more hours of free cooling with little water.

Where towers are used, operation matters. The Department of Energy (DOE) breaks a tower's make-up water into evaporation, blowdown and drift, and says going from three to six cycles of concentration cuts make-up water by 20% and blowdown by 50%.

Does a closed-loop or liquid-cooled data center still use water?

It can. "Closed loop" usually describes the sealed coolant loop that carries heat from the chips or the hall, and it does not consume water in normal operation. But that heat still has to leave the building. If it goes to a cooling tower, water evaporates there. If it goes to dry coolers, very little does.

Liquid cooling can help. Liquid-cooled equipment runs at warmer coolant temperatures, which LBNL says allows more free cooling and less adiabatic assist. But LBNL's base case for liquid cooling uses a waterside economizer with a water-cooled chiller, which consumes substantial water. That is part of why it projects average WUE rising as liquid cooling for AI data centers spreads.

So AI data center water usage depends less on the word "liquid" than on the heat rejection behind it. Dense AI racks draw more electricity, and every kilowatt-hour adds heat to reject and indirect water at the power plant. When a developer says "closed loop", ask what the loop rejects its heat to, and for how many hours a year that uses water.

What about the water used to make the electricity?

Indirect water depends on how the electricity is made, and a National Renewable Energy Laboratory (NREL) review found the plant's cooling system often matters more than its fuel. Once-through cooling withdraws 10 to 100 times more water than cooling towers, while towers consume at least twice as much. Its median figures are in the table below.

With on-site, behind-the-meter generation, the power plant's water moves onto the site. How much depends on the generator and how it is cooled:

• Reciprocating engines. The EPA describes engines cooled by a closed coolant loop that sends excess heat to a cooling tower or a radiator. A radiator rejects heat to air and consumes little water; a tower evaporates it.
• Steam cycles. Gas plants with a steam turbine need condenser cooling. NREL's median is 198 gallons per MWh for a combined-cycle plant with a cooling tower, and 826 for a gas steam plant.
• Dry cooling. A dry-cooled combined-cycle plant consumes a median of 2 gallons per MWh, but NREL puts the national-average output penalty of switching from wet to dry at about 1.7%.

So a gas-powered data center is not automatically low-water or high-water: ask which generators it uses and what cools them. Air permits and emissions are covered in our guide to AI data center environmental impact.

What should a community or landowner ask about water?

A developer should be able to answer these in writing before any approval:

1. How much, and when? Withdrawal and consumption, yearly and on the hottest day, at full build.
2. Which cooling design? What rejects the heat, and how many hours a year it uses water.
3. From where? Municipal supply, wells or reclaimed water; whether the source has run short in past droughts; which permits cover it.
4. What goes back? How much leaves as blowdown or wastewater, what it contains and where it goes.
5. What powers the site? Grid or on-site generation, and how that plant is cooled.
6. What happens in a drought? Whether the site can run without water for a period, and at what electricity cost.
7. Will it be reported? Whether actual water use will be metered and shared.

For landowners, water is one line in a wider site review alongside power, permits and hazards.