Toilet exhaust opinions

Ok guys, settle an argument for us. My husband says we must exhaust our composting toilet through the ceiling of the van, I say the side. Who has any opinions/experience with this? Thanks!

I’m not an expert on the subject of composting toilet ventilation systems; however, I do know that any cut you make on the top of your van has a greater opportunity to leak vs a cut you make on the side of your van. That observation is from being in the automobile business and noticing that aftermarket sunroof kits will occasionally leak. A rear sliding window in a pickup can also leak; but, the roof top cut, in my experience, is more likely to cause problems.

I’ve also noticed that many older motor homes tend to leak from somewhere on the roof and I can’t recall seeing one that leaks from a window. I’m sure they do. Just don’t recall seeing it.

I am quite sure that there are many people of experience who can weigh in on the issue with greater knowledge than I. Good luck. (And put it on the side!)

How about exhaust thru the floor? Would be a short way too.

Choose a spot that is as far away from the doors you would normally use. I mean, if you set up camping chairs and table next to the van you probably do not want toilet smells being blown at your spot.

You will want an active fan there blowing air out with a tight lid, otherwise might happen that the airflow is reversed and… yeah.


I’m no expert, but I thinking that if the vent is higher than the toilet, you might not need a fan. You could still go through a wall instead of the roof. I don’t like holes in my roof either.

If you could eliminate the fan, that would be a huge plus for the electrical system.


"Hope for the best, but prepare for the worst." ~ Murphy

Under suitable conditions, especially if there is an exhausting roof fan, it is possible that part of the replacement air comes thru the toilet vent pulling all the smells into the van. That’s why I suggested forced air output and airtight lid :smiley:

We put ours through the floor. And haven’t had any issues so far. It’s only been about three weeks though. This was the easiest option for us as we already had everything else built out.

In any case, somewhere you can replace the hose if need be.