Originally Posted by cboss
Not sure, but it sounds like a vent problem. All sinks and showers need to have a clear vent to the roof or the side of the camper. Follow the vent lines and make sure they are clear.
Thanks, I’ll have to look at that when I get home, I haven’t been on the roof yet ( no ladder ).
I did notice that there is a vent near the P-trap under the sink when I was looking for the winterizing hose.
Just odd to me that it fills up and the shower being a lower drain doesn’t .