Groundwater contamination is a serious environmental problem, given that all living things depend on this essential resource. Groundwater represents less than 1% of all water found on Earth, but nearly 90% of the freshwater used comes from groundwater (USGS 2016). The problem-based activity described in this article actively engages students in real-world issues related to water. Considering water's unique combination of physical and chemical properties, ability to exist in multiple phases, and daily use in agriculture and industry, it is evident that concepts related to water are vital to many scientific domains, including Earth, physical, and life sciences. These activities also can be incorporated into an interdisciplinary unit (e.g., civics class). This lesson lasts approximately one week, including one day for each of the three sections of the lesson, class and independent time for designing students' solutions to a given problem, and at least one class period for presenting and defending the designs.