This paper focuses on how early Korean sanitary engineers used new sewage treatment plants as an opportunity to redefine sanitation as an engineering practice and to refashion themselves as prestigious engineers. Through academic programs, professional societies, and public service, academics and government officials established new identities of an independent profession as a service to the community. I first track down how sanitation and public health have evolved in 1960s urban Seoul. I argue that early sanitary engineers of Seoul City University differentiated themselves both from civil engineering profession and from municipal public works with new curriculum. I look at the professionalization of sanitary engineers and their branding as environmental engineers with their Korean Society for Environmental Engineers and Korean Environmental Engineering Federation. I conclude with ideas to understand the strategies employed by early sanitary engineers in Seoul such as appropriating knowledge and infrastructure and co-producing profession and identity.