UV light breaks down PFAS: California engineers map the chemistry that turns forever chemicals into fluoride

Researchers at UC Riverside have mapped the chemical reactions behind UV light treatment of PFAS, the persistent compounds known as forever chemicals. The study, published in Nature Water, identifies the reaction pathways and byproducts formed when UV light breaks the strong carbon-fluorine bonds. It also shows the process can convert PFAS into fluoride, giving water utilities a measurable way to confirm the contaminants are actually destroyed, not just transformed. The work matters because PFAS contamination is widespread and hard to treat. Many existing methods only partially break down the chemicals, leaving unknown byproducts behind. With clearer reaction pathways, engineers can tune UV treatment conditions and compare it against other cleanup technologies for real-world water systems. For communities dealing with contaminated drinking water, the research is a step toward treatment methods that are safer, more efficient, and easier to verify.