Abstract: While consumers are concerned about pharmaceuticals and per- and polyfluorinated alkyl substances (PFASs) in their drinking water, the largest threat is from disinfection by-products (DBPs), which are an unintended consequence of using chemical disinfectants to make water microbially safe to drink.  DBPs are formed by the reaction of disinfectants with naturally occurring organic matter, bromide, and iodide, as well as from anthropogenic pollutants, such as pharmaceuticals.  DBPs are present at levels that are orders of magnitude higher than other emerging contaminants, and many have been found to be carcinogenic, genotoxic, mutagenic, cytotoxic, or developmentally toxic.  DBPs have also been associated with cancer, miscarriage, and birth defects in human epidemiologic studies.  However, until recently, most research focused only on the 11 DBPs regulated by the U.S. EPA, and the complex chemical mixture of DBPs in drinking water was largely unknown.  This presentation will cover the state-of-the-science overview of emerging DBPs, including a recent study to identify DBP toxicity drivers in drinking water, a study to assess the impacts of algae on DBP formation, and water reuse.  The ultimate goal is to uncover these risks so that new strategies can be applied to improve the safety of drinking water.