Dick_B wrote:
The aforementioned check valve is typically a cheap plastic thing that should be replaced with something better. To get to it I think the plate mounted on the outside of the camper wall needs to be loosened and pulled out to get at the check valve.
This is why we, on the Forum, suggest the first night should be spent in the driveway!
I fail to see how camping in the driveway would have caught this. Unless, I suppose you try to flush at home.
Glad to see your outing went well other than this issue.
Mike