Building a Vermiculture Compost Toilet

Reader Contribution by Kiko Denzer
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Adobe Stock/Kaleb

Learn how to build this simple, low maintenance compost toilet for composting human waste that makes instant fertilizer by separating solids (worm food) from liquids (fertilizer, ready-to-use).

A compost toilet can be as easy as pooping in a bucket, but a bucket system means another weekly chore emptying and managing smelly buckets. When I moved into my cabin in the woods 20 years ago, I started out with a bucket that I just emptied direct into a hole-in-the-ground, but after I got comfortably moved in, I started thinking about a pooper even mom would be happy using.

Friends of ours (also permaculture teachers: see Proyecto San Isidro) recommended building my toilet over a divided concrete vault, and separating liquids from solids. The separator was just a funnel placed low at the front of the seat, where it would catch and divert urine from any (seated) male or female.

We pee more than we poop. In a compost pile, every unit of high-nitrogen pee needs 40 times as much high-carbon (woody/fibrous) material to keep the little compost bugs happy and making sweet-smelling compost. So keeping pee out of a system reduces stink and volume.

I was mulling things over when another permaculture acquaintance, a brilliant guy named Tom Watson (developer of the low-water Watson Wick septic system), affirmed that compost worms would be just as happy eating my poop as my kitchen scraps.

Letting the worms deal with my waste sounded good. The Mexican design specified an above-ground concrete vault with steps up to the seat, but I was building in an existing building, so I had to keep it low. I dug down, pouring a 2-chamber concrete box, topped with cedar 2-by-6s. I hinged one board to make a seat (for comfort’s sake, it needed to be 7-1/2 inches wide). I covered the bottom of the working chamber with a drainage layer of coarse woody stuff (sticks, big wood chips, etc.). Then I added a funnel below the front of the seat, a pipe to a 5-gallon bucket outside, and some worms. Done! (here are some pictures of a vermicomposting toilet)

The urine does require emptying, depending on the size of your storage vessel. We use the homesteader’s handy 5-gallon bucket. The pee makes a terrific, high-nitrogen garden amendment, which we empty as needed. In spring, my wife takes it for greens and the compost pile; I have to compete to feed my garlic! It’s also great for “activating” your . We find that it’s not necessary to dilute it, though that does make it go further.

It took me more than a year to fill up the first chamber. About the time I switched to the 2d chamber, I had married a lovely lass who celebrated with me when I opened the chamber to investigate what the worms had done. It was ALL perfect: sweet, black, rich, light compost.

My farmer wife, being a bit more cautious, typically runs it through a regular compost pile before putting it on the garden, but those are decisions every person gets to make for themself. (Some research suggests that human pathogens won’t survive passing through a worm’s guts, but I can’t confirm or deny it. If you know more, please comment, and provide a citation!)

Now there are four of us, it only takes about 9 months to fill a chamber, but that’s still plenty of time for the worms to convert all that poop into beautiful compost.

The final, but perhaps most important touch has been to make the pooper into an altar to what is a daily miracle of fertility. Our (framed) instructions feature this, from the Upanishads (it has also become a grace we often use at table):

O wonderful! O wonderful! O wonderful!
I am food! I am food! I am food!
I eat food! I eat food! I eat food!
My name never dies, never dies, never dies!
I was born first in the first of the worlds, earlier than the gods, in the belly of what has no death!
Whoever gives me away has helped me the most!
I, who am food, eat the eater of food!
I have overcome this world!
He who knows this shines like the sun.
Such are the laws of the mystery!

Mom never did give up her attachment to pooping in a porcelain bowl of drinking water, but she did visit us happily and often! And when we used her gift to buy our own acre, the first thing we did was to install a new pooper!


Worms: not just any worms will do.You want compost worms, variously called “red wrigglers,” “redworms,” or Eisenia fetida. They are a bit like sourdough starter: anyone with a vermiculture system can easily get you started. Or you can buy ’em. The queen of vermicomposting (and author of Worms Eat My Garbage) is Mary Appelhof.

Temperature: According to a quick web search worms like warmth, about 40-75 degrees F. Our pooper sits inside one of our (cob) outbuildings, and descends about 16″ or so inches below grade, which helps stabilize temps, winter and summer. Adapt your own design accordingly to keep your worms happy.

• Pee as fertilizer: Steven Edholm, Liguid Gold, by Carol Steinfeld. Scientific American
Watson Wick low-flow septic system
• “Poop In a Bucket,” the best poop song ever, by our Texas friend Frank Meyer. Find it on YouTube!
A Work of Art: stories (mine!), all about restoring art to it’s rightful place as the verb responsible for ALL labor.
• Joe Jenkin’s Humanure Handbook: a sh–y bible (remember, “bible” is just Latin for “book”)
• And if you’re tired of thinking of yourself as just a consumer, and the earth just as resources (convertible only to cash and trash), here’s a book to help you rethink economics (and everything else): The Gift, by Lewis Hyde (I love his original subtitle: “Imagination and the Erotic Life of Property” – but don’t worry! It’s just referring to a fundamental understanding that all property is really just – wait – yes…compost!)

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