the chapter starts by identifying what we currently know about the overall benefits of investing in wss section second we examine how such information can be used to support policymaking for identifying priority investments in wss so as to allocate scarce financial resources to the areas that generate most benefits section finally the chapter explores needs for additional research at both the local and global levels in order to gather additional evidence for sound policymaking and investment in wss section the review found that benefits have been measured at various scales with no attempt at evaluating overall benefits except in the case of meeting the mdgs