Developers are eyeing several Oklahoma communities as sites for huge, hyperscale data centers. These massive facilities can bring an influx of cash to local schools and governments, but they also demand lots of resources.

One of those is water. A data center is a huge building (or sometimes a campus of huge buildings) designed to hold computer servers. Like an everyday laptop or desktop computer, they get hot as they work. But unlike computers at home, a simple fan won’t be enough to cool them off.

Instead, they employ large-scale cooling systems to keep the electronics in working order. And some of those systems require the same amount of water as around 60,000 people — that’s about the population of Enid or Moore.

That could be a big deal for a community like Coweta, which is home to 11,000 residents. Community member Patrick Sampson attended an open house in late October to learn about a proposed data center near his home. He was particularly concerned about how much water the proposed data center would use, and where its wastewater would go. And he said he wasn’t finding solid answers at the meeting.

“If they’re going to be self-sustaining, and they’re going to build their own water treatment facility — great,” he said. “Because then they’re not taking water from the city. They’re not taking water from the water district.”

But the raw water would have to come from somewhere.

A spectrum of water use

Oklahoma City Assistant Utilities Director Josh Morgan said there are options to keep data centers from competing with residents for water. One is to use a cooling system that requires less water.

The thirstiest systems use evaporative cooling. The general idea is that a bucket of water can hold about four times as much heat energy as a same-sized bucket of air at the same temperature. So when cool water comes into contact with hot air, it’s very efficient at removing heat and cooling the air, and it can remove additional heat by turning into steam.

“It’s where they just blow water across some coils, and it evaporates some of the water, but it cools the air and that goes in and cools the stuff up,” Morgan explained. “Evaporative cooling uses a ton of water.”

Some data centers use other fluids to cool their electronics, similar to how HVAC systems work. They don’t require much water, but there’s a trade-off.

“The closed loop systems use a whole lot more electricity,” Morgan said. “Studies that I’ve read have shown that they use anywhere from like 30 to 60% more electricity. So that’s a ton more. It’s really a delicate balance between water and electricity.”

But ultimately, Morgan thinks that a balance can be struck for most places.

“Everybody comes in worried, and for valid reasons,” he said. “They worry about the supply of water and the sustainability of our water supply. But and you know, I talked about evaporative cooling and then, you know, closed loop systems. There’s a lot of options in the middle there.”

Where does the water come from?

Another option is not to pull from the same pool of water that residential customers use.

The water that goes into a data center cooling system doesn’t need to be as clean and refreshing as the water that comes out of your tap. Morgan said data centers can use treated wastewater from city utilities.

“We sell reuse water to two large power plants here in Oklahoma City,” Morgan said. “They already use our treated wastewater for their cooling systems — like, that’s an established practice, industry standard practice for several reasons.”

Oklahoma City generates about 60 million gallons of treated wastewater daily. It’s still a finite resource, but much less valuable than treated drinking water.

“Regardless of the size of your community, if you’re on groundwater or surface water, your supply of raw water to treat and make drinkable is a limited supply,” Morgan said. “Whereas if you’re going to turn around and use ‘reuse water,’ there’s an abundance of that. The vast majority of wastewater that we treat just goes to the creek.”

Another reason a data center might use treated wastewater is that it’s cheap, after accounting for startup costs. The power plants that already use treated OKC wastewater had to pay to install pipelines.

“They have a pipeline from our wastewater plant to their power plant, and then they have another pipeline to return the water back because it’s the same scenario for them,” Morgan said. “That’s really all it takes.”

Oklahoma City Planning Commission is scheduled to consider a zoning application from a data center developer in January. The site for that facility straddles city limits and is mostly located in Yukon, where Mayor Brian Pillmore addressed water concerns in August.

“Water is on my list of priorities as number one,” he told community members at a meeting to discuss a data center ordinance. “The very first meeting that we had with [the developers], I said, ‘Guys, this might be a really short meeting because we don’t have any water to sell you.’ And they sat back in their chair and, and thought about it for a minute, and then we continued the discussion.”

Pillmore said talks could continue due to the possibility of using treated wastewater from Yukon, which generates 1 to 3 million gallons each day. Another possibility is drawing high-mineral water from the aquifer beneath the Canadian River.

“It’s a beginning of a process,” Pillmore said. “They need water. We need water. If that can’t be worked out, well, that’s the crossroads. If it can be worked out satisfactory to both groups, things could move forward at that point.”

Where does the water go?

In Coweta, Sampson is concerned about what happens to the water after the data center is done with it. Will used water be dumped into the Arkansas River upstream of agricultural land and sod farms?

“Unfortunately, it’s going to go downstream,” he said. “They’re going to suck that water up in their agricultural food plots as well as their sod.”

Sampson said he’s worried about contaminants in that water, even though the Environmental Protection Agency regulates any treated wastewater released into waterways. They still allow some contaminants as long as they are below permitted levels.

But according to Morgan, water left over after the cooling process shouldn’t contain new contaminants. Just whatever was in the water at the start of the cooling process, and maybe some algicides the data center might add to keep their equipment clean.

But evaporation means anything present in the water beforehand ends up more concentrated by the end of the process. Mostly, Morgan said, that’s minerals.

“It’s going to be real hard water,” Morgan said. “There’s going to be a lot of those naturally occurring minerals which can then scale up and hurt the AC system.”

Because of that, Morgan said, a data center generally recycles about two-thirds of the water that’s left over after a cooling cycle and supplements it with new water to dilute the minerals. The remaining third is returned to the water treatment plant, or the data center can get an EPA permit to release it back into the environment.

Morgan said utilities departments aren’t generally out to attract large customers. But data center developers are approaching communities across the state anyway.

“We can work with them to figure out what’s the most feasible option where everybody wins,” Morgan said. “That’s what we’re in the business of doing. We’re not in the business of telling anybody no. It’s ‘How can we make this work for everybody?’”

This article was originally published by KOSU. You can see the original story here.