Abstract Peracids have gained interest in the water treatment over the last few decades. Peracetic acid (CH₃CO₃H) has already become an accepted alternative disinfectant in wastewater disinfection whereas performic acid (CHO₃H) has been studied much less, although it is also already commercially available. Additionally, peracids have been studied for drinking water disinfection, oxidation of aqueous (micro)pollutants, sludge treatment, and ballast water treatment, to name just a few examples. The purpose of this review paper is to represent comprehensive up-to-date information about the water treatment applications, aqueous reaction mechanisms, and disinfection by-product formation of peracids, namely performic, peracetic, and perpropionic acids.