Bought a mid 90s camper and not sure about the water hook ups. There are two spots on the back for hose attachments. The second one appears that it is running water into the toilet holding tank because when we had it on and the valve shut we ended up with an overflow. This is in a permanent campground spot and we dump the holding tanks every few days into the sewer just by releasing the valves. There is no freshwater tank system in it any longer as it was removed. Is this normal? Are we supposed to just turn that hose on when flushing out the toilet tank? New to camper ownership and clueless.
It sounds as though it is a flush valve. If the undercarriage is not covered, you should be able to trace the hose to see where it goes. It could also be that they re-routed the fresh water line to become the flush line.
It is normal nowadays to have a flush line installed on your black tank. We normally flush the tank using our flush line about once a week.