Explainer

Water

Cooling with water saves electricity. Cooling without water uses more of it. So the water answer and the power answer move together.

What it is, in plain words

Heat has to go somewhere. Broadly there are two ways to move it out of the building. Evaporative cooling uses water, and evaporating water is very efficient, so it uses less electricity. Closed-loop and air-cooled systems recirculate a coolant instead, so they use much less water and more electricity.

That’s the trade-off, and it’s why “we use almost no water” and “we’re a large electrical load” tend to show up in the same project. Neither claim is a lie. They’re two ends of the same design decision.

What the evidence actually shows

• Reported, not verified. US data centers together were estimated to use about 449 million gallons a day, roughly 163.7 billion gallons a year, in a 2021 estimate.^[1]
• Reported, not verified. A single large hyperscale facility can use up to about 5 million gallons a day, comparable to a town of 10,000 to 50,000 people.^[1]
• Reported, not verified. An International Energy Agency estimate cited in the same synthesis puts a 100 megawatt facility at roughly 530,000 gallons a day, varying by cooling method.^[1]
• Reported, not verified. US data center onsite water use is projected to grow two to four times between 2023 and 2028.^[1]

For Carroll County specifically, there is no published gallons-per-day figure. What exists is the developer’s own commitment. In the agreement announced with the City of Carrollton in late July 2026, the developer pledged a closed-loop coolant system. The reporting describes it as requiring minimal water.^[2] That number is not quantified in the source, and it comes from the developer, not from a regulator or an independent study.

There is a state-level hook worth knowing about. The executive order signed August 6, 2026 directs the Energy and Environment Cabinet to deny certain permits. The list covers projects that would negatively affect water use, water quality, water supply, federal jurisdictional wetlands, or natural resources.^[3] That puts water in front of a state agency with a permit decision, which is a place where evidence can be filed.

What’s contested or unknown

“Closed loop” isn’t a single defined thing with one water number attached to it. Ask what it means in this specific design, because that’s where the answer lives, not in the phrase.

Also unknown for Carroll County: where the water would come from, and where the discharge would go. The reporting places the Carrollton site next to Carrollton Utilities’ regional wastewater treatment plant, with the Kentucky River on the north edge of the property.^[2] That makes both questions concrete and answerable. They just haven’t been answered publicly yet.

Questions worth asking at a hearing

• Where does the water come from? Municipal supply, a river withdrawal, or wells?
• How many gallons a day at full build-out, and how many on the hottest week of the summer? Those are different numbers.
• If the design is closed loop, how much makeup water does it still need, how often, and from where?
• Who holds the withdrawal permit, and what happens to the facility’s draw during a drought or a low-flow period?
• Where does the discharge go, at what volume and temperature, and what treatment does it get first?
• Is there a written cap on water use in the agreement, or only a description of the intended system?
• If the cooling design changes after approval, does the project have to come back for a new review?
• Who monitors the actual usage once it opens, and is that data public?