My Sawdust Toilet Experiment

by Rhona Mahony. I’ve written here (“Water is Precious, Poop is Priceless”) about the advantages of dry toilets. They conserve potable water. They produce organic fertilizer. Those results are good, because many people in the world don’t have clean water to drink. Instead, they get sick. What’s more, many poor countries spend scarce foreign exchange to import synthentic fertilizer. Experiments with different kinds of dry toilets and collection systems can take place anywhere, at many scales. It is possible that advocates of dry toilets might not be merely loony, tree-kissing ascetics trying to take the fun out of our bathrooms. Finding a smart way to dispose of, and even make use of, human manure for the 21st Century could have big pay-offs.

I want to test how practical it really is to lug buckets of sawdust and human manure around the house. My test is easy in one way: I am the only person in my family of five using the dry toilet. That leaves me with one-fifth the lugging. It is harder in one way, though, from the experience of someone whose town is collecting the toilet contents. I am doing my own composting.

My System

The Compost Pile

Human manure has to be composted to be safe to apply to crops. The nitrogen that human urine contributes to the pile helps feed friendly, heat-producing bacteria. Their heat kills pathenogenic bacteria. The result, after about a year, is safe, rich fertilizer. That’s the theory.

I built my compost corral out of bamboo stakes, a small-mesh fencing material called bird wire, and plastic cable ties. My corral is roughly three feet tall (one meter), and three feet by three feet in surface area. If I need to expand it, I can reposition the bamboo stakes and lengthen the fence by tying on another strip of bird wire.

The Sawdust

The dry toilet needs several inches of dry, fine, and fluffy organic material at the bottom. After each use of the toilet, a couple of inches of this fluff must cover the urine or stool.
I shopped around for free sawdust from sawmills, lumber stores, and furniture makers, but couldn’t find any nearby. I am using wood shavings from a horse stable near me, Webb Ranch. Here is Summer Hensley, the stable co-owner, with my bag of compressed shavings. She charged me $7.50.

The Toilet

I’m using five-gallon (19-liter) plastic buckets. The toilet seat, with a hinged lid, snaps tightly on top of a standard five-gallon bucket. A Canadian company called Reliance makes the one that I bought: the “Luggable Loo.” I bought it from Cabela’s, an outfitter for hunters and fisherfolk. I do not feel a need to enclose the buckets in a rosewood cabinet. I settled for painting a flower on each one. Can you smell the rose?

Observations

The wood shavings are coarser than sawdust would be and, as a consequence, take up more space vertically in the bucket than I would like. My bucket fills up in only four days. I expected a week. That is annoying me. I have the telephone numbers of sawdust sellers in San Jose, California, which is 20 miles (12 k.) south of me. If I get annoyed enough, I’ll call them.

The dry toilet doesn’t smell any more than a conventional water toilet. I was afraid it would. That’s a big relief.

My compost pile also smells fine. It smells like straw. I had been putting about eight inches of cut grass on top of each five-gallon bucketful of food scraps. This layering is working well for the dry toilet’s contents, too. I have no verminous creatures rooting in the pile. No neighbors are complaining.

The lugging is a chore. Having an additional toilet receptacle to wash out is also a chore. Of course, if my whole family had switched to dry toilets, we’d have only buckets to wash.

I’ll post reports in the future about how this experiment is going. Are you doing similar experiments?

A relevant book: Joseph Jenkins, The Humanure Handbook: A Guide to Composting Human Manure, (Jenkins Publishing, 2005)