Mystery chemical in drinking water identified

For decades, scientists have known that a mysterious chemical forms when inorganic chloramines are used to disinfect water. But they didn’t know this chemical’s molecular formula or structure. Now the mystery molecule has been identified as the chloronitramide anion. Little is known about this anion or its toxicity. Approximately 113 million people in the US consume drinking water disinfected with the inorganic chloramines NH 2 Cl and NHCl 2 , according to the US Environmental Protection Agency (EPA) . This type of water treatment has grown in popularity as people seek to avoid dangerous disinfection by-products that form with chlorine treatment, which is more common . But chloramine treatment also creates disinfection by-products, and the identity of one of these had long eluded researchers. “Despite being able to reproducibly form the unidentified product for over 30 years now, prior characterization efforts have been stymied by analytical limitations and an incomplete