Data Centers, Microbes, and the Future of Water Reuse
Through a Sustainability Next Seed Grant project administered by the BBISS, Graham's lab focuses on water reuse safety, particularly in Georgia communities facing water stress.
As metro Atlanta becomes a magnet for hyperscale data centers, the region faces a twin challenge: securing enough water to cool these facilities while ensuring that wastewater reuse doesn't introduce new public health risks. At Georgia Tech, Katherine Graham, assistant professor of environmental engineering and Brook Byers Institute for Sustainable Systems (BBISS) Faculty Fellow, is working at exactly that nexus, using viruses, bacteria, and advanced analytics to understand how water reuse and cooling systems can support data center growth without compromising community health.
"Data centers are important, and so are their cooling needs. I don't think they're going away," she said. "But there needs to be a lot of investigation to develop guidelines for operating these facilities based on how microbes behave so that we can get the economic benefit and protect the communities where they operate."
Tracing Viruses Across Georgia's Water Systems
Through a Sustainability Next Seed Grant project administered by the BBISS, Graham's lab focuses on water reuse safety, particularly in Georgia communities facing water stress. Her team works with municipal reuse facilities, where, she said, “We look at what comes out of wastewater treatment plants, what exists in the natural waters they discharge treated water into, and what comes into downstream drinking water plants at their intake." Her team is especially interested in pathogens such as viruses and phages.
Phages — viruses that infect bacteria rather than humans — pose no direct human hazard. Still, because they travel through water systems similarly to viruses that can harm people, they serve as powerful ecological markers. "They can be good surrogates for human viruses," she said.
This work builds on Graham's wastewater surveillance experience dating to 2018, which became central during the Covid-19 pandemic. Her lab helped develop actionable public health guidelines to show how wastewater can be used to monitor for mpox outbreaks.
From Cooling Towers to Data Centers: A Proactive Public Health Lens
While Graham's Sustainability Next Seed Grant project isn't exclusively about data centers, the connection to their cooling systems is direct. Data centers need to dissipate massive quantities of heat — typically with water-hungry cooling towers — and are increasingly turning to treated wastewater as a supply.
"Reuse can supply more water of sufficient quality for these cooling systems," Graham said. But beyond the quantity issue lies an underexplored dimension: microbial risk.
Cooling towers have long been linked to Legionnaires' disease, with documented outbreaks occurring miles downwind of a source. "For most healthy people, it may not be a problem," Graham noted, "but for the immunocompromised and elderly, it can be a really big problem." What makes this especially concerning is how little is known. "It's not well quantified. It's not well characterized," she said. "There's been no national study collecting cooling-tower waters and looking at the prevalence of these bacteria."
There is currently no systematic, national effort to characterize the prevalence of Legionella and other opportunistic pathogens in any cooling towers — let alone the potential additional risk of building more cooling systems to accommodate the needs of hyperscale data centers.
BBISS has been central to sharpening her focus here. Exposing Graham to colleagues working on energy and water quantity challenges helped her connect the microbiology dots. "A lot of the data center ideas I've started to think about have been generated by BBISS faculty presenting their own work," she said. "Given that cooling towers are already a problem in pre-AI settings, it seems like a good proactive idea to be aware of the problem going into the age of AI."
Graham is now writing proposals to study microbial communities in cooling towers, analyzing water, air, and biofilms under different operating conditions. Her call to industry is direct: Partner early. "I would be extremely happy to collaborate with anyone interested in this problem. Industry buy-in would be critical — and so helpful — to get it done."
Heat Waves, Infrastructure, and Legionella
Graham's lab also examines how climate-driven extreme heat affects drinking water systems. Working with utilities in the Southwest, her team studies how prolonged heat waves warm distribution-system water, accelerate disinfectant loss, and shape the persistence of microorganisms in drinking water distribution systems.
"We were able to see temperatures above 40 degrees Celsius (105 degrees Fahrenheit) — with a maximum of 52 (126 degrees Fahrenheit) — which is very warm," she said. "Most of the literature refers to testing conducted at much lower temperatures, like room temperature." Such elevated temperatures, combined with nutrients and stagnation, can allow opportunistic pathogens to thrive.
Teaching and Outreach
Graham teaches undergraduate environmental engineering and graduate courses in quantitative microbial risk assessment and public health microbiology. She serves as associate editor for Water Research and has hosted a microbiology outreach workshop for K-12 students through Georgia Tech’s Center for Education Integrating Science, Mathematics, and Computing (CEISMC).
The through line across her work is consistent: science that anticipates risk and informs action. "As we expand this data center infrastructure, a proactive approach should be taken to understanding concerns that, maybe, haven't been fully addressed yet."
In a region and a world betting big on AI, her research offers a timely reminder: Progress depends not just on computing power, but on ensuring that the water that keeps these systems from melting down remains safe for the communities living alongside them.