USA FACTS Data centers and water: Answering your questions

Friday, October 23, 2026

USA FACTS Data centers and water: Answering your questions

Welcome back to Spotlight, the once-a-month email where we focus on one thing we just had to show you.

This time we’re doing something new: answering your questions about this article on AI data centers and electricity bills.

You overwhelmingly wanted to know about data centers and water.

Particularly: with water-demanding data centers popping up nationwide, does that leave enough available for everyone else?

Trygve, one of the co-authors of the original article, has the answers.

Or, as many answers as he could get, which was tricky.
Here’s what he had to say.
He even threw in key questions to keep in mind at the bottom.

(See his full responses in the article.)

How much federal data is there about data centers and water?

Not much. Why? I’m unsure, but I speculate that it partly has to do with the necessary data being proprietary and/or paywalled for competitive reasons.

It could also be that the AI industry is developing faster than any government system designed to track its requirements and effects.

How much water do data centers use?

Each data center is different. That said, a 2024 study with the most recent government estimates on data center water usage showed that they directly used 5.6 billion gallons of water in 2013 and about 17 billion gallons in 2023. That’s nearly tripled in 10 years,

Some back-of-the-envelope math shows that 17 billion gallons was equivalent to the annual water use of about 389,700 people in 2023. That’s a bit less than the population of Wichita, Kansas, which was the 52nd largest city in the nation that year. (See how we got there with the full equation in the article.)

But that’s 2023 usage. This study doesn’t capture recent AI data center construction.

How much water do large data centers use?

I don’t really know. I often see claims like:

“… a large data center will use up to 5 million gallons of water every day …”

I tried tracing that 5 million figure to the source but ran into a dead end at "researchers say," without finding any additional citations or evidence. It's a number that's often referenced, but never sourced.

So, I dug further and found designations for reserved water and used water. Does that have anything to do with this large number? Maybe! I go into more detail in the piece!

How does a data center use water?

Data center servers, computers, and other equipment generate a lot of heat. They use water to cool everything down. Let’s focus on the two types of liquid-cooled systems: closed- and open-loop.

A closed-loop system fills with water, absorbs the heat, then passes the water through chillers to cool it down so it can be used again. A true closed-loop system requires little additional water once it’s operational because it’s not exposed to the air. They tend to be more water-efficient and more energy-intensive.
An open-loop system also absorbs heat, but it cools the water by exposing it to the air. It requires a continuous water supply to replace what’s lost to evaporation. These tend to be more energy-efficient and more water-intensive.

Here’s a simplified schematic of an open-loop cooling setup.

What’s up with data center wastewater?

Most, but not all, wastewater is generated during data center construction and as it starts to come online. Preparing the cooling equipment for water circulation involves processes that can result in “… short-term, high-volume discharges with higher pollutant concentrations than those generated during operational phase.”

Most often, wastewater is discharged to a collection and treatment system. This requires a permit from the system operator. Another way is to get an EPA permit to discharge wastewater directly into a water body.

Again, there's not a lot of data on this, but the article runs through some of the things to keep in mind about wastewater and where that water comes from to begin with.

Is AI really a big part of the economy?

On August 28, the Congressional Research Service noted that:

“… several large technology companies with significant AI-related activities … account for more than 40% of the S&P 500’s total market capitalization.”

I’m not a finance guy, but here’s what that’s saying: the money invested in AI is a big chunk of the value of the stock market right now.

You might (correctly) argue that “the stock market” is not the same as “the economy,” so here’s another data point: The St. Louis Fed estimates that AI spending — which includes data center construction — accounted for 30% and 11% of GDP growth in the second and third quarters of 2025, respectively.

A final point: the Census Bureau estimates that the private sector invested more than $7.5 billion in data center construction in August 2026.

Key questions to ask:

As you develop an understanding of how data center water use could matter for your community, keep these points in mind:

Data center size. The bigger it is, the more cooling needs it will have.
Data center cooling tech. How is the data center planning to cool its equipment?
Actual use vs. guaranteed access. Is water use data actually describing water use, or describing maximum water use? If the latter, how often will the data center use that maximum?
Reuse potential. Is any of the water that’s withdrawn available for reuse, or is it all used consumptively?
Water source. Where does the water for the data center come from, and will it self-supply or get its water through the local water utility?
Wastewater. How is the data center planning to dispose of wastewater it generates?