Greywater reed beds are simplistic systems for filtering used water into something clean enough to irrigate with. A horizontal delivery pipe drops the water through large boulders, and the water then soaks under a bed of gravel. The gravel is 65 centimeters deep and the water level sits at 60 centimeters, i.e. below the surface, where roots from reeds take minor toxins out of the water. When the water rises to the surface, it’s time to open the tap and drain the system down to the base level again. The water from the reed bed is perfect for irrigating trees. There are three of these reed bed systems on the Greening the Desert site, so there is no greywater that doesn’t go to irrigation. The kitchen has a reed bed with a grease trap between it and the garden. At the back of the organic café’ greywater from the sink goes through a similar system, only the reed beds are a series of bathtubs followed by a gravel-filled trench (also planted to reeds). Eventually, the cleaned greywater from the café feeds a banana circle. This is how every last drop of greywater goes to growing something at the Greening the Desert project.