It was an email from a colleague that tipped off environmental engineer Detlef Knappe of possible 1,4-dioxane contamination in the Cape Fear River Basin, North Carolina’s largest watershed and a source of drinking water for communities across the state. The Environmental Protection Agency has classified 1,4-dioxane as a probable human carcinogen. With support from a National Science Foundation grant, Knappe and his team at North Carolina State University have begun to identify 1,4-dioxane sources and how 1,4-dioxane impacts drinking water quality. Knappe is also working with managers at water treatment plants and state policymakers in North Carolina to improve testing and treatment standards for 1,4-dioxane. Part of the National Science Foundation Series “Science Nation.”