If for any reason you have decided to use flush toilets at your project and are not connected to a mains sewage treatment system, then it is most likely that you will have an underground septic tank and soak-away system. These are sometimes leaky and contaminate groundwater or well water. This design is an improvement on the conventional septic tank and leach-field design which uses plants inside a sealed open-topped tank as a living filter to evaporate excess water into the air, and to consume and benefit from the nutrients in sewage. At the same time we gain a valuable yield of food and biomass. All food from fruiting plants are 100% safe from any contaminants that may be in the sewage.