So many drain lines....

I have a 3500rl Bighorn. There are three drain lines in the back of the trailer(I think at least one is fresh water overflow). There is one near the docking station which drains the fresh water w/pump on and valves in docking station turned to drain. Another near that one w/valve on end of hose. What do all these hoses do? Any help will be appreciated...

Pigcooker. Heartland has changed the drain and or vent hoses a couple of times since day one. A lot depends on what year your trailer is. The ones in the rear of the trailer are more than likely to be fresh water tank vent lines. The one by the docking station with the valve should be the manual fresh water tank drain and the one without the valve can be used to drain the fresh water tank with the 12v water pump. On that line I put a 1/2" barbed male hose connector and sometimes use it for a garden hose or dog wash hose. I gave up on trying to use the factory hose plug ins on either side of the rig.

Two of them should be low point drains, 1 for Hot and 1 for Cold. Part of preparing for long term storage and or winterizing. One to drain the fresh water tank.