A simple reed system can clean washing machine and bath water enough to grow rice. What better place to do than the roof which in tropical India receives a lot of sunlight. Nutrition for the rice comes from a Ecosan unit on the roof again, which provides the urine for fertilizer. Finally a solar box cooker cooks the rice for consumption. Food and water Cycle complete on the roof. The water for the washing machine and bath comes from harvested rain falling on the roof but a slightly different part. Learn how to use grey water to grow rice paddy by watching this video tutorial.