On a small strip of land between the Emscher River and the Rhine Herne Canal in Germany sits a rest stop whose colorful appearance belies its radical purpose. The structure’s artful design consists of pipes leading from two toilets and the Emscher (the most polluted river in Germany) that converge at a small community garden and drinking fountain. The garden is, in fact, a manmade wetland that collects, treats, and cleans the effluence from the toilets and river—making it drinkable.