Sanitary and combined sewer overflows (SSOs and CSOs) as well as storm water discharges are considered wet weather flows (WWFs), all of which introduce pathogens to surface water bodies. As such, a disinfection technology that is cost competitive, environmentally friendly and has a minimal footprint is needed to address large volumes of WWFs as opposed to existing technologies which are many times cost prohibitive, yield toxic by-products and often require more space than is available in areas of older infrastructure where the WWFs are a problem. The use of peracetic acid (PAA) has been investigated as one such possibility for high-rate disinfection. The decomposition of peracetic acid results in only the non-toxic by-products of oxygen, methane, carbon dioxide and water, and the disinfection reaction occurs in a short contact time and with a high kill rate of pathogens. Thus, this technology can prove not only valuable where space is limited, but is also extremely environmentally sound. Further, the optimal combination of PAA and the contact time needed to reach water quality standards has been explored to determine the most cost competitive combination for cost comparison and the determination of cost competitiveness with other existing or currently used disinfection technologies.