The purpose of this presentation is to focus on the forgotten hero of public health John Leal, and how he and George Warren Fuller together paved the way to fight water born diseases. Through their efforts of using chlorine as a disinfectant, it was possible to control water borne diseases, which killed many people at the beginning of the 20th century. Dr. McGuire's career has included years of service at both drinking water utilities and consulting frims. He is also the Editor-in-Chief of Journal AWWA.