A septic tank is made out of concrete, and the waste goes into there. Periodically, it has to be emptied, and a service comes and pumps it out into a container, which they then take with them to wherever. I think this is a point of contention, when you hear about trucks emptying into streams and rivers illegally. Also, if it gets VERY full, and it rains a lot, it will overflow. there's a lot about this I do not know. It just seemed to me at the time, that it would make a good garden. This was before I knew about disease in human waste and other things going down the drain!
