Yes. I am an Industrial Engineer with a Masters in Systems Engineering. The Systems Engineering really focuses on large complex systems such as water treatment plants. My Masters research project was to design a water treatment system in Antarctica to support 5 scientists over 4 months, using as little energy as possible. It was a fun project. I had another product design project in an elective class where I had to redesign a Brita water filter.
I know people working for a water treatment plant. They mostly hire chemical, biological, and environmental engineers, but they also hire civil, mechanical, industrial, and systems engineers. These engineers all understand the basics of fluid mechanics and fluid dynamics so they often work on the technical side of water treatment plants focusing on maintenance and performance of pipes and water filtration/treatment equipment and machinery. The chemical and environmental and biological engineers work on the water quality side, focusing on the cleanliness and safety of the water, as well as the performance of the water treatment system.