How to Empty a Composting Toilet: TMI Alert

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We built the most awesome composting toilet, based on the Humanure Handbook, with some of our own mods. At first, we were skeptical that it would a) not reek, and b) not be disgusting to manage. But because we’re working on the permaculture principle of starting with simple, slow, cheap solutions, it was a good place to start. To my pleasant surprise, it has turned out to be better than we could have hoped. Here’s the update on the composting toilet emptying process. It’s not as bad as you think. And infinitely better than emptying the RV toilet tank. Pee-yew!

First, after getting a small bucket of sawdust from the lumber yard weekly, we upped our request to a giant binful, so we wouldn’t have to go there as often. Mauricio salvaged this nice bin from the construction site where we works. It sits right next to the Shouthouse, and doesn’t look too shabby.

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After about a month of using the composting toilet full-time, our family of five managed to fill five buckets, all of which we acquired from our garbage pile. We did buy lids for them. Here’s what the toilet looks like mid-week. You know, in case you were wondering. As you can see, if you train your kids correctly, it’s no grosser than looking at toilet water. It’s just some sawdust, maybe with a little t.p. peeking out.

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In about a week, one bucket gets filled, thanks to liberal use of sawdust covering (the key to being stinkless). We put a lid on it, and then stick behind the Shouthouse.

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Once we got the critical mass of buckets, or rather, ran out of lids, it was time to build the compost bin. It’s basically a square box filled with covering material, where the contents of the buckets can be dumped safely.

First, we had to find the best location for it. Seriously, this took as much time as it took to build the thing. Mauricio was not convinced that it wouldn’t stink and wouldn’t attract flies, so he wanted it as far away as possible. I, on the other hand, wanted it close to the Shouthouse and not uphill, for easy bucket transport and emptying. I also needed it to be near a water source for rinsing out the dumped buckets.

We finally agreed on a site that would meet both our criteria, and I got to work leveling it (easier said than done when you’re pick-axing your way through serpentine rock), while Mauricio got to work pulling nails out of our salvaged wood that I had garbage-picked earlier. Our good friend, leverage, was put into play again as the kids helped pull apart some nailed boards.

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I also want to add a tip here about one of our most-used tools. It’s a hammer/nail puller/multi-purpose leverage device on steroids. We call it the Vampire Slayer, and we find a use for it on every project.

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Building the compost bin was easy enough. We just cut some plywood to a 4’x4′ size and deck-screwed it into some 2×4 post corners the same height. It has no bottom, and sits directly on the leveled ground. The front, though, has a clever little feature that allows you to slide up half the plywood in order to have easy access when doing the dirty work. It’s basically a 2×4 sandwich, attached to the lower, permanently attached half of the plywood square side. We put the rocks that were dug up while leveling all around the base of the bin to discourage critters from digging under.

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Then we went to our local feed supply and got four bales of straw for our cover material. We used a whole bale to make sure we could get stuff good and covered. Giovanni was all over the process of filling up the bin. I made him promise he wouldn’t try to play in there after we emptied the bins. That kid.

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Then it was simply a matter of making a hole in the center of the straw, dumping the buckets in, and rinsing them out with a dedicated garden hose right over the pile. I used a dedicated toilet brush to swirl around and dump the water in the compost bin. I put the rinsed buckets out in the sun, which is really good at disinfecting, and then added a scoop of sawdust before stacking them up for the next round of usage. Lastly, I just covered straw over the dumped bucket contents with a dedicated rake that really only touches the straw.

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You’re probably wondering, so I’ll tell you. Yes, I could see poo when the buckets were dumped. But it’s kind of all covered with sawdust, so it’s not that big a deal, and again, not nearly as stinky as the RV toilet. It’s mostly dry, like changing cat litter, with some wet sawdust at the bottom that necessitated the rinsing.

You’re also probably wondering what happens to the compost. Supposedly, you use the bin for a year, then let it do its composting thing for a year, while you start a second bin. After that, you have compost you can disperse at the base of trees. We’ve got a few years before we have to deal with it. Right now, I’m just happy to have a closed system for our waste, which doesn’t involve flushing drinking water or digging an expensive, disruptive septic system.

Next dump (ha, so to speak), I’ll add in some weeds, since the compost pile needs both carbon (straw and sawdust) and nitrogen (green plants or other food scraps) in order to reach temperatures high enough to kill pathogens and decompose safely.

For now, I’m happy to report no flies, smell or foraging critters. Pretty low maintenance. About $75 to make the composting toilet, free sawdust from the lumber yard, free salvaged material for the bin, and $34 for the hay.

The smell of sweet success: Welcome to Poo Corner.