Dirty water in toilet bowl after sitting

TheMohns wrote:
I parked my trailer in storage last week and just went to check on it today. The black tank was about 1/3 full when I parked it and I left the toilet bowl filled a few inches up with clean water. When I checked it today, the bowl was filled with dirty sewer water. How could it get from the black tank up into the bowl?

It can't,(shouldn't) unless;
1. Your flush seal is bad, in which case, it probably wouldn't have held water in the bowl in the first place.
AND
2. Your tank was much more full than 1/3, it would have to have been FULL (over full) in conjunction with a bad seal.

Do you have water hooked to the trailer? Or,water in the fresh water tank & the pump left on, is there a cap on the black tank vent pipe,
Are you sure it was sewer water?