What is really in your drinking water? Researchers uncover the hidden chemistry behind disinfection
About 98 percent of water utilities in the United States disinfect drinking water with chlorine and its compounds to protect communities from bacteria and other microbes that can cause serious illness. Yet the same chemicals that kill harmful organisms can create dangerous compounds known as disinfection byproducts, which have been linked to health concerns such as bladder cancer and reproductive damage.
"Improving drinking water treatment remains one of the most important scientific challenges of our time," said civil and environmental engineering doctoral student Kadmiel Adusei. "Every advance has the potential to protect millions of people from sickness and death by delivering water that is both microbiologically safe and chemically cleaner."
In a study published in Environmental Science and Technology, Virginia Tech researchers evaluated whether an alternative chlorine-based disinfectant could help achieve both goals.
The research was led by Adusei, whose work earned national recognition by placing second in the 2026 American Water Works Association ACE Fresh Ideas Poster Competition. He was chosen to represent Virginia after earning first place in the fall 2025 WaterJAM drinking water competition.
Working alongside his advisor, Kirin Furst, associate professor in civil and environmental engineering and co-director of the Occoquan Watershed Monitoring Laboratory, Adusei gained hands-on experience investigating complex water treatment challenges.
"Working with Dr. Furst has fundamentally changed how I approach research," Adusei said. "Her mentorship has shown me that impactful science is not only about making discoveries, but also about asking the right questions and ensuring those discoveries are understood and applied effectively."
Alternatives to traditional chlorine
The chlorocyanurate disinfectants that Adusei tested offer several advantages over traditional chlorine. They are more shelf-stable and easier to store and transport, making them especially useful for small water systems, emergency response, and communities where maintaining a reliable chlorine supply can be difficult.
But an important question remained: Are these alternative disinfectants actually healthier?
"Chlorocyanurates show real promise as an alternative to conventional chlorine, but we need to understand whether they truly reduce health risks or simply create a different set of byproducts," said Adusei. "Answering that question is key to developing safer drinking water treatment."
Advancing the measurements
Adusei and Furst compared water treated with chlorocyanurates to water disinfected with traditional chlorine. Rather than focusing only on the most commonly regulated byproducts, they measured a much broader range of compounds that can form during treatment.
"The most impactful advances are those that address both microbial risks and chemical contaminants simultaneously," said Adusei. "Partial safety is ultimately insufficient for the millions who depend on every drop."
The researchers found that chlorocyanurates reduced several well-known disinfection byproducts while increasing the formation of other, less-studied compounds that may also present health concerns, according to the study.
Rather than identifying a single "best" disinfectant, the findings show that the safest choice depends on the chemistry of the water being treated. Factors such as water quality and composition influence which byproducts form, meaning an approach that works well in one community may not in another.
"Researchers have long assumed chlorocyanurates were more stable than conventional chlorine," said Furst. "This work challenges that assumption by showing they can form potentially harmful byproducts that we've largely overlooked, particularly in communities where poor sanitation may already increase exposure to these unregulated compounds."
A tool for the future
The findings do not suggest chlorocyanurates should be eliminated as a drinking water treatment option. In many situations, particularly where reliable access to traditional disinfectants is limited, their stability and ease of transport remain important advantages.
But Adusei's work highlights the importance of understanding the full chemical picture when evaluating new approaches to water treatment.
"The goal isn't just to kill harmful germs. It's to make sure the treatment process doesn't create new risks," said Adusei. "That's how we'll continue improving the safety of drinking water."
Original study: DOI 10.1021/acs.est.5c07394
