It’s been fascinating to watch data center liquid cooling technology — pretty much the definition of behind-the-scenes plumbing — become a high-profile part of the data center discussion. As just one example, Texas Gov. Abbott this month cited requirements for water-efficient, closed loop cooling among the six data center issues he pledged to hit next fall with lawmakers.

If it’s your job to actually choose, implement, and operate these liquid cooling environments, we had a recent webinar on trends, pitfalls, and benefits that you might want to catch on replay. Below are eight nuggets from that discussion. To start, here’s one inspirational gem from Raymond Parpart, University of Chicago’s director of data center strategy and operations, who runs about 80% of the data center environment on liquid cooling, and is working on a design to expand the data center with no additional mechanical cooling:

“If we're not trying to eliminate mechanical cooling at this point, I think we're falling short of where we could absolutely be from an efficiency perspective,” Parpart says.

Here are some quick-hit nuggets from the webinar, which featured Parpart, Apolo CEO Bill Kleyman, and Accelsius product marketing director Lucas Beran:

Air cooling’s not cutting it. Soaring rack density for AI workloads mean air cooling increasingly just can’t physically handle the heat. “AI density is forcing quite literally a reset in terms of how we dissipate heat from mechanical equipment,” Kleyman says. In the AFCOM State of the Data Center Report, 39% of operators say their current cooling doesn’t meet their needs, and 64% use liquid cooling or are planning to adopt it within 24 months.

Liquid can’t cool it all, yet. Parpart estimates the university’s environment is about 80% liquid cooling, focused on CPUs and GPUS, with systems such as memory and power supplies still using air cooling. But at those levels the university is leading edge. Industrywide, data centers will hit 50% of all cooling using liquid around 2030, Parpart estimates.

Where to run the water. One thing people underestimate when considering moving from 100% air to adding liquid cooling to a data center is physically where the water will run, Parpart says. Some start planning and realize their floor can’t handle the added load, for example, or that their ceilings are too low to run it overhead.

A warning sign you need liquid cooling. Beran offers the simple metric of tracking your current cooling system utilization. Is it regularly running at max, or quickly trending upward? Densities can quickly get ahead of cooling infrastructure.

Better cooling to avoid expansion. As power becomes a growing constraint for data centers, one way to expand compute capacity is lowering the amount of energy used for cooling by improving efficiency. Beran cites a company that moved to liquid cooling because it was spending 40% of its power for cooling: “They said, we want to deploy more IT in the space. How do we do that? Let's not spend 40% of our power envelope on cooling.”

Water means maintenance. PG-25 (25% propylene glycol, 75% water) is common in single-phase liquid cooling, but even that mix requires topping up, PH testing, and other maintenance steps to keep it from corroding the system, Beran notes. (Accelsius sells two-phase liquid cooling that mitigates much of the maintenance.)

Water will leak. It can be hard for veteran data center operators to get comfortable with the idea of water running through the operation. Parpart says leaks are inevitable, and it faced that problem with the first system it implemented. “Did we panic and freak out? Oh yeah, because I had water in the data center,” he says. “But what we did is we learned. We have mitigation protections — leak detection, fluid detection. You just have to know it's going to happen, and you have to be prepared to handle it.”

Parpart left the audience by focusing not on fear of what might go wrong, but with encouragement to embrace technology that will be necessary for many data centers to meet demands in the coming years.

“Don't be afraid. Try. Reach out to colleagues. Start small and grow from there,” he says. “And don't think just because you're in a little space it’s not for you, we're not all going to do 1 megawatt racks. Most of the people on this call are not hyperscalers. You're like me. Think big, start small.”