Operation Water Biology (OWB) is a series of eight lesson plans designed for use with students in grades 9-12. OWB directly connects with science, chemistry and biology curricula and covers several different aspects of drinking water treatment. The major topics are chlorine, chloramine, ammonia and iron. For each of these there is a discussion explaining what it is and its importance to drinking water treatment. There are also lab activities for each which allow students to work with small amounts of these substances and see them in action. Students will demonstrate the idea of chlorine demand, create chloramine through a simple chemical reaction, test local samples of drinking water for chlorine and ammonia, and filter water samples with iron oxidized by different processes to determine if one is superior. Every lesson includes additional suggested activities and resources, along with references to other sources of information.