Students act as engineers contracted by NASA to create water filtration devices that clean visible particulates from teacher-prepared "dirty water." They learn about the worldwide need for potable water and gain appreciation for why water quality is an important issue for people on Earth as well as on the International Space Station. Working in groups, students experience the entire engineering design process, including a read-aloud book about the water cycle; a visiting water engineer presentation; their own online research about filter methods and designs; group brainstorming of designs (using ordinary household materials); filter construction and testing; redesign and retesting; lab book documentation of their notes, research, plans and results; and a summary poster presentation at a mini-engineering fair. Two design planning worksheets, a poster layout suggestion sheet and a grading rubric are provided.

This activity focuses on getting students to think about bacteria, water quality and water treatment processes. Students develop and test their hypotheses about the "cleanliness" of three water samples prepared by the teacher. Then they grow bacteria in Petri dishes from the water samples. They learn how private septic systems and community sewage and wastewater treatment plants work, the consequences to the surrounding environment and wildlife from human wastewater, and what measurements of the released "clean" water are monitored to minimize harm to receiving rivers and lakes.