This testimony describes what happens to the water that flows through a so-called ‘closed loop system’ used to cool AI data centers.
Editor’s Note: When data centers are proposed, people often are told by industry representatives that the water used to cool the computers is in a ‘closed loop’ system. This implies the water continues to circulate and doesn’t need to be refreshed. Here’s information from Oracle: “In a closed-loop system, like your home air conditioner, the cooling fluid stays within sealed pipes and is repeatedly reused, rather than consumed.” However, according to a study from the University of Michigan, “some individual data centers use hundreds of millions of gallons annually, dwarfing the usage of entire communities the data centers are within. Most facilities use over 10 million gallons (38 million liters) of water per year.”
Below is a transcript from a video recording of testimony by Tammy Clark, Industrial hygienist, Environmental Health Specialist, to the Michigan House of Representatives, “Subcommittee on Corporate Subsidies and State Investments,” February 4, 2026. The video is from a Paul Rivera Facebook post.
“There’s really no such thing as a closed loop system. It’s still picking up water. That water in a closed loop system is being contaminated. It’s picking up anti-corrosives, anti-scaling agents, biocides, and then what is happening is — that water gets what’s called blow down. It gets blown back down into the aquifers or the rivers, or like what Ohio EPA is just right now allowing. They just dump it right back into the river. The water treatment facilities are not capable; they do not have the filtering media and they’re not capable of filtering those particular types of corrosives. And so that just makes its way down into our aquifers, and most of these communities are small towns and farming communities that have wells set on aquifers. So this water, this grey sludge basically, is not being cleaned, it’s not being filtered and it’s being dumped right into our drinking water, or it’s being dumped into a water treatment facility center that cannot handle that kind of load.”
