[ontheroad10]

I wonder if anybody has had this experience. I recently had my toilet replaced and some vents also repaired. No problem when I take the rig out for a couple of weeks.

Problem is at least 3 times, after storing the rig, I come to find the toilet is full of sewage that I can't explain. I finally called the shop and asked if they could explain it. They say they have never heard of anything like this. I plan on taking it out this week, but the problem doesn't occur until I store it.

Can't understand how pressure can build up for an upward flow from the black water tank, but there is evidence on the toilet lid that something shot upward.

Any ideas?