Researchers have identified a chemical in certain tap water across the United States as chloronitramide anion. Here's what to know.

A newly identified compound in tap water that had eluded scientists for decades prompts safety concerns for a third of Americans.

Some water systems decided to use chloramine -- a chemical compound formed by mixing chlorine and ammonia -- as a disinfectant instead. Chloramine forms fewer byproducts than chlorine and is believed to be more stable, making it useful for water systems that deliver water over large distances.