To figure out your RV’s holding tanks, you need to do a short experiment. You need to test out which handles go with which RV wastewater tanks.
One of the first thing I do with a new RV is to make sure all of the tanks are empty. Pull each handle that you see and empty the tanks into the campsite sewer.
Then, one by one:
- go to a sink/shower/toilet/washer drain and run water for a minute
- go outside and pull each handle until you find which one is tied to that fixture; write it down on a note and close handle when the water is done emptying
- repeat until you’ve hit every water fixture
It helps to have a clear piece on your sewer outlet so you can really see what’s going on.