Do Data Centers Use a Lot of Water?

Servers turn nearly all their electricity into heat, and something has to carry that heat away. The cheapest way at scale is evaporative cooling: air passes over wet cooling towers, water evaporates, and the phase change hauls the heat off. It works beautifully — and it consumes fresh water continuously, because evaporated water doesn't come back. That's the key distinction: this water is consumed, not borrowed.

The numbers vary enormously by cooling design, which is why any honest answer starts with "which kind?"

For scale: one of Google's biggest U.S. sites, in Council Bluffs, Iowa, withdrew about 3.9 million gallons a day and consumed roughly 2.8 million of it, per Google's own environmental report. A peer-reviewed analysis found a single megawatt of evaporatively-cooled capacity drinks about 18,000 gallons a day — so a 100-megawatt facility, a common size for new builds, lands around 1.8 million gallons daily.

The counterweight: a facility on air cooling or a closed loop uses almost no water on site — it just pays more for electricity instead. And the newest AI hardware runs so hot it needs liquid cooling, which circulates coolant in sealed loops with near-zero fresh water. The industry's water trajectory is genuinely better than its electricity trajectory. When a developer says "closed-loop cooling," that's a meaningful claim — but it's worth asking them to put the actual gallons-per-day number in writing, because "closed loop" still needs an initial fill and makeup water.

To judge whether a data center could strain your water supply, you have to know what your supply is. Here's the verified picture for our area:

Bartlett: Lake Michigan. The village's own documents state plainly that "Bartlett's source water, Lake Michigan" — purchased through the DuPage Water Commission, which receives treated lake water from the City of Chicago's Jardine purification plant. Fun history: as recently as 2017, Bartlett bought about 60% of its drinking water from the city of Elgin before completing its switch to the DuPage Water Commission.

Elgin: the Fox River. About 75% of Elgin's raw water comes from the Fox River, with the remaining 25% from deep wells, per the city's own history page. Its Riverside treatment plant can process up to 32 million gallons a day. Notably, Elgin's official history says the decision to return to the Fox River "has continued to help Elgin attract large corporations and developments, many of which would not locate here without an ample water supply." In other words, Elgin has been marketing its water abundance to industry for decades.

One more piece of context: Illinois' Lake Michigan supply is not infinite. A 1967 U.S. Supreme Court decree caps the state's total diversion at about 2.1 billion gallons per day — shared across Chicago and more than 200 suburbs. Every new large user in the region draws from the same court-ordered pie.

This is the question that actually reaches your bill. When a giant new water user shows up, somebody has to pay for bigger mains, upgraded pumps, and expanded treatment capacity. The standard answer from utilities is "growth pays for growth":

• Connection and capacity fees. New large users pay one-time charges scaled to the capacity they need — often calculated per "equivalent dwelling unit." The whole point is that existing customers don't absorb expansion costs.
• Developer-funded upgrades. Charlotte, North Carolina's water utility — dealing with the same data-center wave — requires each proposed facility to undergo capacity review and hydraulic modeling, and says the developer pays for main extensions, line upgrades, and capacity improvements. Charlotte Water told local media that data centers operating there "have not caused residential water or sewer rates to increase."
• The peak-demand problem. Here's where it gets honest: a data center's water use swings with the weather — far more on hot days. Columbus, Ohio is currently pushing to bill data centers for peak water use, because its utility has to build infrastructure sized for the worst days while the current fee structure only really captures average consumption. As one city official put it, the question is whether high-volume users "pay their fair share for the amount of investment that is needed to deliver peak water capacity."

The bottom line: the system is designed so you don't pay for a data center's water. Whether the fees fully capture the true cost — especially peak capacity — is the legitimate open question, and it's being litigated in rate cases, not settled.

You don't have to look far to see this play out. In 2026 alone:

• Morris — an alderman voted against the Tract 1-gigawatt data center campus citing water usage and the possible need for a new water facility the city might have to help fund.
• Joliet — residents sued to stop a proposed $20 billion campus, arguing it could draw 100,000–150,000 gallons a day from an aquifer already projected to fall short of peak demand by 2030.
• Mahomet — after secret talks leaked, the developer's draft capped potable-water fill for its closed-loop cooling at 750,000 gallons per phase, with the rest from reclaimed wastewater — a sign of how seriously the Mahomet aquifer (drinking water for nearly a million people) is being guarded.
• Barrington Hills, Naperville, Lisle, Belvidere — a $2 billion campus withdrawn, a 145,000-square-foot proposal killed, another paused, and "Project Hawkeye" opposed at a packed council meeting — all with water among the cited concerns.

The pattern: communities aren't debating whether data centers use water. They're debating whose water, how much, and who pays for the infrastructure. Those are exactly the right questions — and they're the ones to ask if a proposal ever lands near Bartlett or Elgin.

For the full picture on data centers and your other utility bill, see our companion piece on whether data centers raise electricity bills, and our guide to data centers near Bartlett for the verified nearby facilities.

• Read your village's water quality report. Bartlett publishes an annual Consumer Confidence Report — it lists your water source, what's in it, and how it's treated. It's the most boring useful document your village produces.
• Watch for the capacity question. If a large development is ever proposed near you, the question to ask at the village board meeting isn't "will it use water?" — it's "what's the peak-day demand, and what capacity fees is the developer paying?"
• Know your own usage. The average American household uses about 300 gallons a day. A single medium data center matches a thousand of you. That ratio is the context for every local debate.
• Fix your own leaks first. A running toilet can waste 200+ gallons a day — the unglamorous truth is that household waste is the part of the water bill you fully control.