Toilet backfilling

[lord1234]

So the toilet on my boat is backfilling. I am unsure if its just not properly getting to the waste holding tank or the tank is full. However, its "in the bowl" right now, and the boat is on a trailer, so getting it to a cleanout risks spilling some. What should I do to trouble shoot this issue/what could be causing it?

 

[alldodge]

What kind of toilet, there are different types

 

[Tassie 1]

New problem or " new boat "?

 

[FunInDuhSun]

First step, get the bowl empty. A few years ago I did this using a small shop vac. It was VERY nasty but did the job.
Only then you can start to diagnose the problem. I had a partially collapsed waste line.