That would be a typical septic system, you should (if you actually could) see the leach field here at work for the car wash. it covers the entire front of the entrance, then there's a septic system and before that there is a clarifier system for recycling and reusing the car wash water within the car wash itself. We's a green car wash. Of course it is only the car wash that recycles not the bathroom.
![Ack :ack:](https://board.marlincrawler.com/Smileys/marlin/ack.gif)