Hi, I’m confused about the best way to vent a simple humanure-style compost toilet located in a bathroom.  Is it better to place the fan as close to exit of vent pipe, so that it sucks rather than pushes the air?  It might be quieter, too, if it’s not in the toilet box.  Maybe the fan could be located outside, even?

Also, if there is a competing shower fan in the room, then how to prevent it from drawing air out from the toilet box (and stinking up the bathroom)?  I have read that the shower fan intake could, instead of being above the shower, just be the same vent pipe as the toilet box, drawing air through the toilet box.  In other words, the toilet box fan creates a relatively weak continual air flow, but when the shower fan is turned on then it just adds more power and so more air goes through the same pipe.  The advantage, apparently, is that there is no competition between fans, and humid air is drawn in at a low point, thereby keeping heat in the bathroom.

But, maybe this is just overkill?  Because, if the shower fan inlet is above the shower (as usual), then wouldn’t simply opening the window provide a source of incoming air, be enough to prevent sucking air from toilet box?

In Laura’s video about compost toilets, she for some reason seals with foam the top of the toilet.  Doesn’t that prevent air from coming in to the toilet box, to be vented?  Won’t it also cause condensation on the toilet seat (because of lack of air flow around the seat)?

Thank you for the help!

  • You must to post comments
Best Answer

Hi Eric,

For a true humanure style toilet you don’t need any ventilation. The sawdust or woodchip cover you add to the bucket seals off most odors, and since the bucket is filled rather quickly, there isn’t time for odors from decomposition to develop. Other styles of composting toilets that keep the material around for longer, or may have urine storage that has urine odor, will need a fan or vent.

I currently have a simple humanure sawdust bucket toilet, and we use woodchips to cover, no vent, no fans. No odor issues. The  standar bathroom fan doesn’t draw up odors. The issue with the bathroom fan you bring up is when there is a larger composting chamber below the toilet, that would be a source of more odors, which doesn’t happen with a 5 gallon bucket sawdust toilet.

A previous toilet I had, with urine diversion, had more odor from the urine tank so the seal on the toilet lid helped with that. I don’t find it necessary for a sawdust bucket toilet with no urine diversion.

If I were you, I’d set up your sawdust bucket toilet, experiment with cover materials, and see how it works without a fan. You could always add one in later on. (I would except you not to need any fan or vent.)

Hope this helps!



  • You must to post comments
Showing 1 result
Your Answer

Please first to submit.