This week has been spent designing the plumbing systems. This has been a little more intense then originally anticipated due to the slope requirements of the waste pipes. In a normal house this is not a major issue because the waste are below grade and can be sloped simply by digging a deeper trench as long as the depth works with the municipal sewer system or for the private septic system. In a house that is re-using grey water in the planter beds elevation is critical to assure that the proper slope is maintained and making sure that the piping is high enough for the water to be usable at the plants. If you review the drawings provided in the previous posts you will see the indoor planter beds. in order to maintain the proper slope I have done a layout that runs some of the waste in the walls and then drops to just below the slab so the the elevation of the piping at the flower beds is less than 4″ below the slab which should work fine. The greenhouse planter beds will be lower than indoor beds so drainage should not be a problem.

For those that are not familiar with the concept of re-using grey water I will try to explain it as best as I can. All grey water generated in the house is directed to planter beds that are constructed so that the grey water passes through them, hydrating the plants, providing nutrients and along the way is biologically cleaned by the plants. Any water that completes the passage through the beds can be re-used for use in the toilet or it can pass to the sewer system (septic in our situation). We will not be re-using the treated grey water to eliminate one complexity to the system and eliminate the slight odor produced by using the treated water in the toilet. More information on this concept can be found at

Since the basic concept of an Earthship is to use low voltage power for as much of the equipment as possible, all the lighting and pumping systems require DC pumps which lends itself to using RV type pumps effectively. However as you will see in my discussion of the electrical systems that has raised new issues.

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