When it comes to composting toilets, we thought we had seen it all, but we missed the Bio-Lux. This Japanese unit uses sawdust as an "artificial soil matrix" to decompose human waste into odorless water and carbon dioxide through aerobic fermentation. You empty it twice a year and toss the compost in your flower garden. Most units are pretty industrial looking, but they are available in all their throne-like glory for residential use. These are big high capacity units: the smallest can be used 16-20 times per day, the biggest up to 200 times per day. But they are also not cheap, starting at about US$ 10,000.
There are good reasons for using composting toilets and for bringing them into the mainstream; all of the other water that we use in a home can be treated as grey water and re-used for irrigation, green roofs and other useful things. Connecting the toilet contaminates the whole thing, creates the need for expensive infrastructure and sewage treatment plants- Imagine if all that came out of your house was water for irrigation and compost for your garden- it really isn't waste at all. To paraphrase Alex Steffen, "Waste is just useful stuff in the wrong place at the wrong time"