Peracetic acid (PAA) is the active component of a series of disinfectant products developed for the treatment of wastewater. These products have only recently been introduced onto the market so little published information exists about their efficiency. In this work the disinfection efficiency of PAA has been experimentally studied on raw wastewater, along with eventual regrowth after the ocean discharge of the treated water. Great variability has been observed in the inactivation of total coliforms by PAA, the influence of the pH of the wastewater was noteworthy. The disinfection action takes place in short times (around 5 to 10 minutes). After disinfection and mixing with real sea water the total coliforms present greater T90 values and disappearance times, having increased their concentration under laboratory conditions and in darkness.