Andrew Maynard is at it again, with Poop House, his answer to the Australian drought. Water is too valuable to be just something that is just used; he turns it into the main structural element of the building. Thinking that the greenest building is no building at all, the structure is nothing but an inner and outer layer of polyethylene forms. When you build your house you purchase enough water to fill the inner transparent form, which takes the shape of an arch.
As you use the water from the inner arch, it is then pumped into the outer arch; the weight of the outer black and grey water keeps the inner arch in place as the water is moved from one to another.
As the solids in the black water settle to the bottom, the liquids are removed, reprocessed and re-used so that it is a closed system. Eventually after about 20 years the outer arch is filled with dry solid waste, and the inner arch can be removed or refilled.