Latest twist in Minnesota data center debate: How much water they will consume

Questions about the quantities of water needed to keep data centers cool has become another point of contention in the debate over the industry's explosive growth in Minnesota.

That water use isn't nearly as dramatic as the electricity needed for the data centers planned in Minnesota, which could surpass the usage of every home in the state.

But planning commissioners in one Twin Cities community have cited demands on water infrastructure as a reason to block a project. At the Capitol, DFL lawmakers want data centers to publicly disclose how much water and energy they use. In other communities, residents and environmental groups worry about the local effect on their groundwater.

Jeff Camden was one of dozens of local residents at an open house in the tiny south metro city of Hampton earlier this year for a data center under development by the Minnesota firm Oppidan. Many worried about water.

"What's that going to do to the people that have wells?" Camden said.

Data center companies and city officials have made at least an initial water estimate for five of the 11 proposed data centers. So far, none in Minnesota would come close to the volume consumed by the state's biggest users, such as power plants or industrial farms.

"We actually have significantly more issues with trying to keep up with irrigation on people's lawns," said Matt Podhradsky, city administrator in Chaska, where New York-based developer CloudHQ hopes to build a data center.

Still, in the early stages of these projects, some companies building data centers don't yet know how much water they will use because they haven't settled on a cooling technology. Others are protective about the details of their operations and divulge little to nothing about their water plans.

A national trade organization for the data center industry is fighting at the Legislature against the disclosure bill, saying it would expose their trade secrets and make their data centers a potential target for terrorists.

How and why data centers cool

Data centers are warehouse-like facilities filled with rows of servers. Those computers generate enough heat that they need a reliable cooling system.

Microsoft estimates that a data center that uses 40 megawatts of electricity — which is smaller than projects now under development in Minnesota — produces enough heat to supply 46,000 households in the winter.

Minnesota's cold winters mean data center companies don't have to use much water for most of the year, said Thom Jackson, a mechanical engineer for Dunham Associates who designs cooling systems for data centers.

On warmer days, the cooling options for data centers come with tradeoffs.

One is a refrigerant-based technology that is similar to a home air conditioner. These systems use no water, but they need a lot of electricity, said Jackson, who is president of the Minnesota chapter of a national organization for professionals in the data center industry.

Other common systems need a steady supply of water, but far less power. They are generally cheaper because of smaller electricity costs, but can lose some of that water through evaporation.

Somewhere in between is what Jackson described as an "air-cooled chiller," which uses refrigerant and water to cool, but without evaporation. It's a closed system that doesn't need to be replenished once it's filled, Jackson said.

Water projections vary widely

There is a wide range of potential water use estimated by data centers in Minnesota.

Facebook's parent company, Meta Platforms, plans to use a closed-loop cooling system at its $800 million project in Rosemount, said spokeswoman Stacey Yip.

Rosemount estimated Meta would draw 100,000 gallons of water each day from the city's groundwater system at peak use. Yip declined to confirm the figure or offer an estimate.

That's about one-sixth of an Olympic-sized swimming pool.

Farmington has estimated the Colorado-based developer Tract could use nearly 24 times that much every day, at least at its peak, roughly the water use of 11,600 homes.

In a December interview, Graham Williams, then chief investment officer for Tract, said the industry is moving away from the most water-intensive cooling technologies and that times of peak demand are short, so the company would not use that maximum amount every day.

Chaska expects CloudHQ to draw about 1.5 million gallons per day at its peak from the city's groundwater but less at other times, said Podhradsky, who noted the city has plenty of capacity.

Oppidan says its planned Apple Valley campus would use about 8 million gallons of water per year. The Minnesota Zoo uses eight times more water each year, according to Apple Valley.

Amazon and Microsoft declined to estimate their potential water use but each said their operations will replenish, rather than deplete, supplies. Amazon spokesman Duncan Neasham said the company uses no water to cool data centers in Ireland and Sweden for "95% of the year."

Faribault officials said that they expect developer Archer Datacenters to build a closed-loop project that wouldn't be water-intensive, but that it's too soon to estimate water use.

Localized groundwater risks

Most companies and cities that responded to the Minnesota Star Tribune said the data centers are expected to draw from groundwater, not lakes or rivers.

Heavy groundwater use has risks, said Carrie Jennings, research and policy director for the nonprofit Freshwater. Many of the potential projects — in Farmington, Hampton and Rosemount — are in Dakota County, which Jennings called "one of the most irrigated counties in the state."

When groundwater is sucked up more quickly than rain and snow can filter back down to replenish it, that creates a "cone of depression" — a zone where the water table is lower. This can dry out shallower household wells on the fringes of small towns, Jennings said.

Jennings said that for communities that rely solely on groundwater, eventually "it either limits growth, or you have depleted groundwater."

The Minnesota Department of Natural Resources issues permits for high-capacity water users. An agency spokeswoman wrote in an email that the "DNR cannot issue a water appropriation permit if it will cause higher-priority water users (like domestic wells) to run out of water."

Still, Jennings predicted, "You're going to see more conflict with private well owners."

There's also the risk of depleting surface water by pumping too much from the ground. In a letter to the Legislature, Minnesota Trout Unlimited said groundwater springs are the "lifeblood of trout streams," and the Tract data center in Farmington would draw on shallow aquifers that support the Vermillion River trout fishery.

High-volume groundwater water usage in other industries has also raised water quality issues. When Elko New Market tested a higher pumping rate in advance of a new water bottling plant, residents found dark and murky water running through their pipes. The substance that had been released was manganese, which discolored fixtures and clothes, and is harmful to ingest in large amounts.

Building infrastructure

Some cities also might not have the water infrastructure to support a data center, or fear a data center would take water that could be used for other expected growth.

Apple Valley's planning commission worried that the city lacked the water treatment capacity to sustain future development, including a data center.

"If our infrastructure is not there, it's not there," planning Commissioner Becky Sandahl said during an April 2 meeting. "I don't see how we could move forward."

The Apple Valley City Council has yet to weigh in on the land use change that would make way for a data center. Public works director Matt Saam said city officials worked for months with Oppidan to reduce its initial water request but are seeking an even lower number.

Hampton, home to some 700 people, hasn't approved a project yet. An environmental review adopted by the City Council Tuesday shows one scenario in which the data center would use up to 12.5 million gallons of water per year. That could require Hampton to construct more wells and capture rainwater, the document states.

But officials won't know how much water a data center could consume — and any infrastructure changes required — until a concrete proposal is on the table, Hampton City Engineer Cory Bienfang said.

"This project is still arguably unknown," he said. As for what that means for the city? "We haven't studied that yet, because we don't know what is being built."