A concerning revelation has emerged about the water that flows from American taps: approximately 90 percent of public drinking water systems contain disinfection byproducts, many of which remain unstudied and unregulated. These chemical compounds form when water treatment facilities add disinfectants to eliminate dangerous pathogens, but the resulting byproducts may pose their own health risks, including increased cancer risk.
While the Environmental Protection Agency (EPA) currently monitors four categories of these byproducts, scientists believe hundreds or potentially thousands more exist without regulation or thorough understanding of their health impacts. Research indicates that some of these compounds could be present at concentrations 100 to 1000 times higher than other water contaminants.
Water treatment facilities face a delicate balancing act. They must source water from surface bodies, groundwater, or recycled sources, then treat it through multiple steps including coagulation,
flocculation, sedimentation, filtration, and disinfection. While UV light and ozone treatments are sometimes employed, chemical
disinfectants remain necessary to ensure continued pathogen protection as water travels through distribution systems.
Recent studies have highlighted significant health concerns. Research published in Environmental Health Perspectives demonstrated that trihalomethane exposure increases bladder cancer risk by 33 percent and colorectal cancer risk by 15 percent, even at levels below current regulatory limits. Additional research has linked these compounds to miscarriage and birth defects.
Professor Susan D. Richardson from the University of South Carolina, a leading researcher in this field, notes that water distribution pipes essentially function as reactors where these byproducts can form, degrade, or transform into other compounds during transit. Her forthcoming research examines the behavior of 66 different
disinfection byproducts as water moves from treatment plants to households.
Fortunately, consumers have options to reduce their exposure. Home filtration systems utilizing activated carbon or reverse osmosis technology can effectively remove many of these compounds. A 2017 study confirmed that reverse osmosis systems can simultaneously eliminate both organic and inorganic byproducts. Water pitcher filters also offer some protection, though consumers should verify NSF certification for specific contaminants.
For those seeking cost-effective solutions, simple methods can help. Storing water in the refrigerator allows byproducts to dissipate naturally. Research has shown that storing water with or without a lid can reduce trihalomethanes by up to 47 percent, while boiling water for one minute before storage can decrease levels by up to 92 percent.
At the treatment facility level, advanced technologies show promise. The Environmental Working Group reports that modern PFAS treatment systems can reduce trihalomethane levels by 42 percent and haloacetic acids by 50 percent. However, only 8 percent of U.S. water treatment plants currently employ these advanced systems.
The American Water Works Association emphasizes that while various technologies can help minimize byproduct formation, chlorine or chloramine disinfection remains essential for maintaining water safety during distribution, as mandated by EPA regulations.
Concerned citizens can access water quality reports through their local utility companies, utility websites, or the EPA’s Consumer Confidence Reports webpage. These reports typically detail levels of regulated byproducts, inorganic contaminants, and other potential concerns, while also indicating whether the water originates from surface, ground, or recycled sources.