While the world struggles with limited water resources, interflow water is a hidden gem of a solution. Interflow is an important water source contributing to river flow. It is the movable water in the unsaturated zone, or vadose zone, which may return to the stream or go into the riverbed. The collection of interflow water was included in the design of the Erfeng Irrigation Canal System (EICS) during the Japanese period in Taiwan (1895–1945), and it is still used in the EICS in Pingtung in southern Taiwan. Today, urbanization and changes in land usage have reduced the EICS’s irrigation function. At the same time, intensive habitation has introduced pollution to the canal area. Furthermore, new extensions and rebuilt facilities of the irrigation infrastructure have minimized historic values. We are involved in working to maintain the canal in a way that safeguards cultural heritage values and to expand other functions of EICS, such as by installing micro-hydro facilities over the canal to preserve its importance to local communities.