Due to the LOW amount of flush water because it is a direct deposit device with the poop NOT traveling to a tank it is BIG at 9.5 gallons
We are pretty good about timing are deposits and while we did have it pumped twice in 2011 we cold have gotten by with once
Tommays, I don't understand what you are saying there. Where does the poop go if not into the tank?
The manual says it uses an average of one quart per flush. If you add in the urine and the solids. The way I figure it, you will probably get around thirty uses before having to pump out. Depending on how many people, especially females are using it, that's pretty good.
I would certainly choose a system that had it's own self contained tank before I ever went back to a traditional set up. If it smells anything like a port-a-potty though, I wouldn't want anything to do with it.