Peracetic acid has quickly gained ground in watertreatment over the last decade. Specifically, its disinfection efficacytoward a wide spectrum of microorganisms in wastewater isaccompanied by the simplicity of its handling and use. Moreover,peracetic acid represents a promising option to achieve disinfectionwhile reducing the concentration of typical chlorination byproductsin thefinal effluent. However, its chemical behavior is still amplydebated. In this study, the reactivity of peracetic acid in thepresence of halides, namely, chloride and bromide, was investigatedin both synthetic waters and in a real contaminated water. Whileprevious studies focused on the ability of this disinfectant to formhalogenated byproducts in the presence of dissolved organic matterand halides, this work indicates that peracetic acid also contributesitself as a primary source in the formation of these potentiallycarcinogenic compounds. Specifically, this study suggests that 1.5 mM peracetic acid may form around 1-10 mu g/L of bromoformwhen bromide is present. Bromoform formation reaches a maximum at near neutral pH, which is highly relevant for wastewatermanagemen