The Nonguén estuary in Concepción, Chile, is heavily urbanized. It is subject to considerable levels of pollution, caused by waste and untreated greywater. In contrast, water is a scarce resource in the area, as droughts have become more frequent due to climate change. In an effort to raise environmental awareness, reduce pollution, and improve locals’ living conditions, a group of women involved in garden activities at the local elementary school built a “worm filter,” that is, a biological system capable of treating greywater with living worms and wetland plants.