In this chapter, a unit on water quality ends with a water filtration engineering design activity and was a win-win situation. Students were already very curious to learn about water filtration after their study of water properties and water quality problems and issues. Getting them actively involved in design and construction of a model that actually did change the polluted water helped them understand more about not only filtration but also engineering design. A materials list, teacher background information, and outcomes are provided. This book selection includes the Table of Contents, Introduction, References, Internet Resources, and Index.