A minimalist composting toilet

If you've read The Humanure Handbook, you know the idea: instead of flushing waste "away," you mix it with sawdust or similar material, then compost it in a hot pile.

If you're not comfortable with the idea of composting feces, you might use just your urine. It's far safer--in fact, many experts recommend peeing in your compost to give it a good shot of nitrogen. I set up the system used by humanure folks, only I limit it to urine. My main goal is to get good compost I can comfortably use on food crops.

Basically, you put some sawdust in a bucket. You pee in the bucket and toss in some more sawdust. When the bucket is full, you dump it in your compost.

Most people build nice enclosures that hide the bucket. Here's a more minimal and portable approach that works best for those who sit. My only cost was the $14.99 toilet seat.

You can get the same inspiring yellow stain if you use the bucket to mix iron sulfate.

The seat sits directly on the bucket. Plastic bumpers keep it from sliding. In front, a fat wire hooks the seat to the bucket to keep the seat from tipping back when you lift the lid.

Materials

• 5-gallon bucket with a handle (no lid necessary)
• standard toilet seat with 3 or more removable bumpers on the bottom. Get a seat with decent hinges so you can lift the lid without the seat trying to follow.
• about 6 inches of thick wire (I used aluminum ground wire)
• a screw eye the wire will fit through
• a wax pencil or other marker
• (probably) a drill and assorted bits

I bought a seat that had 5 plastic bumpers on the bottom. The bumpers had feet that fit snugly in holes. To move the bumpers, I popped them out of their factory holes, drilled new holes, and pushed the bumpers into the new holes.

Procedure

1. Remove the bumpers from the seat bottom.
2. Put the seat face down on the floor, put the bucket in place on the seat, and trace around the bucket. Remove the bucket.
3. Reinstall the bumpers along the circle you marked so they'll keep the seat from sliding on the bucket.
4. Put the bucket right way up on the floor and put the seat in place. Turn the bucket if necessary so one of the handle attachment points is toward the front. You'll attach a wire to the handle at that point and hook it through an eye in the bottom of the seat.
5. On the bottom of the seat, mark a good spot for the eye to go. Install the eye.
6. Loop the wire around the handle where it connects to the bucket and make a hook at the other end to go through the eye.
7. Set your new toilet near a wall, so when you raise the lid it has something to rest against.

Use

This procedure is for urine only. Urine is supposedly safe after 24 hours. If you want to compost your other fertilizer as well, you need a guaranteed hot compost pile and more time. See The Humanure Handbook for details.

1. Near the toilet, put a container of sawdust or other dry, brown organic matter. I use fine planer shavings from a sawmill.
2. Put some sawdust in the bottom of the toilet.
3. Pee in the toilet. Toss the paper in there, too.
4. Add a big handful of sawdust to the toilet.
5. Repeat steps 3 and 4 until the toilet has enough contents to justify a trip to the compost pile.
6. Dump the bucket in the compost. Bury or layer the contents--whatever technique you usually use.
7. Rinse the bucket. Dump the rinse water in the compost, too.
8. Optionally, let the bucket sit in the sun to sanitize it.
9. Put about an inch of fresh sawdust in the bucket and start again.

Other designs

A nice wooden box.

Another minimal approach that uses a flange cut from a second bucket.