How to Build a "Tree Bog" Composting Toilet

tree bog composting toilet photo
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When I wrote about garden mulch as composting toilet, it drew complaints from one disgruntled reader and compost-toilet geek who noted that this was really a composting urinal, not toilet. He was, of course, right. For those interested in the real thing, Permaculture Magazine has featured some of the finest examples of plush and fragrant composting toilets that are designed to handle anything nature throws at them.

Now they have a great account of how to build your own "tree bog" composting toilet. The only trouble is, the author has sat on some of "the most beautiful toilets in the world." Nothing like setting yourself up with high expectations. But while the end design he comes up with may not be a thing of great beauty, it's about as simple and elegant a solution for human waste as I can think of. We've posted before about the adventures of former wildlife film makers Tim Green and Rebecca Hosking as they try to convert a family farm for the post-fossil fuel world. But this latest installment, describing how they built their very own Tree Bog composting toilet, is worth another visit. (Bog, incidentally, is a common British slang word for toilet.)

As Green notes, his former filmmaker like has taken him to some stunningly beautiful outhouses from South India to Nepal to Kenya. But struck by a sudden drying up of their on-farm Spring that supplies their household water, Green and Hosking were forced to think and act fast in creating an effective composting toilet system. Besides the ease of speedy construction, the pair were also looking for minimal maintenance—for fairly understandable reasons:

"So the design brief Mother Nature had set was to build a waterless closet that could be up and functioning within a couple of days. To that I added "and requires no maintenance". It's not that I'm overtly squeamish about poo (hard to be a livestock farmer if you are!) but given a choice of emptying toilets or not, I'd always choose the latter. To my mind the only answer was a treebog."

The Tree Bog, as Green explains, is a pretty simple idea. Essentially a platform is built to house the toilet itself, and around that platform you plant willows and other heavy-feeding tree species that can absorb the nutrients (note they are now nutrients, not pollutants!) from your toilet and turn them into valuable biomass. The only maintenance needed is occasional coppicing and "peak knocking". (Green declines to explain what that is, but he suggests we can probably figure it out.)

There is a little more work involved in keeping undesirable critters out of the deposits, and making the structure itself comfortable and habitable, but it's certainly not rocket science. Head on over to Permaculture Magazine for a full rundown of how to build a tree bog composting toilet, as well as some instructions on how to manage what you put in it.