Well AnEv942 the small door on the left of the main door is the sewer dump. I appoligize I didn't get pictures today and I work the rest of the week early to late so it will have to be this weekend before I get over there. Anyway there is a tank a long one probably 2-3 feet long on the left side of the camper on the outside. when we back the truck under the camper to load it you have to be careful backing up with the bed liner it scrapes along it at your backing in, we are planning on taking the bed liner out for ease of loading. its either a black tank or the grey tank, I don't know which need to ask DH. We don't know where all the pipes are from and where they go to, we haven't dug into that mess yet.