The aim of this study was to propose a risk assessment method for infectious diseases, using reclaimed water as a case study. To evaluate the infectious risk of norovirus (NoV) in various applications of the reclaimed water, five types of ultrafiltration (UF) membrane treatments were considered: (1) coagulation with low pH + UF membrane process, (2) UF membrane process alone, (3) UF + ultraviolet (UV) irradiation process, (4) UF + nanofiltration (NF) membrane process, and (5) UF + reverse osmosis (RO) membrane process. These treatments were used in a pilot plant and the NoV concentration after each treatment process was studied over the long term (2010–2014). Infectious risk was described using disability-adjusted life-year (DALY) when the reclaimed water was applied for agricultural irrigation, landscape irrigation, recreational enhancement, and toilet and urinal flushing. The results show that reclaimed water could be considered acceptable for recreational enhancement by adding a UV, an NF membrane, or an RO membrane treatment to the UF membrane treatment process.