How to Build a Homemade Composting Toilet

A composting toilet is ideal for a rural property but can also be fitted into the house.

A very simple composting toilet can be built inside your home or in an outdoor shed or shelter. If you locate the toilet outside, it's best placed on a slight slope, downwind of the house, although a well-maintained compost toilet does not develop odors. Be sure to avoid damp, moisture-collecting sites outside, and have separate toilet and bathtub or shower chambers inside if possible. The most basic designs require only a wooden box or platform with a plastic bucket plus a regular hinged toilet seat with a lid.

Difficulty:

Moderate

Instructions

Things You'll Need

• ¾-inch plywood board, 18 inches square
• ¾-inch plywood board, 3-by-18 inches
• Long hinge or 2 shorter hinges
• 2 boards, 1-by-10-by-20.5 inches
• 2 boards, 1-by-10-by-18 inches
• 4 boards, 3/4-by-3-by-12 inches
• Standard toilet seat and hardware
• 4 identical 5-gallon plastic buckets with lids
• Sawdust or other cover material
• Container and scoop for sawdust
• Screws
• Electric or manual screwdriver
• Nails and hammer (optional)
• Tape measure
• Pencil
• Saw
• Paint or clear lacquer (optional)
• Paintbrush (optional)

1. Build the box or platform for the seat. Screw together the 20.5-inch and 18-inch boards to make a rectangle. Cut a hole in the 18-inch square board just big enough so a plastic bucket rim can fit into it snugly. Trace around the rim with a pencil for your cutting guide. Set this hole about 1.5 inches in from the front of the square.

2. Hinge the back of the square to the 3-inch by 18-inch board to make the seat platform. Screw the 3-inch wide piece of lumber to the top-back of the rectangular base. The 3-inch piece of wood is now attached to the box and the hinged 18-inch square sits on the box and can be lifted.

3. Fit the plastic bucket into its hole. Measure how tall to make the legs so the bucket sits directly under the box, protruding ½ inch up through the plywood. Screw the four legs to the inside corners of the box, trimming them for height if necessary. Paint or seal the wood box now, if you plan to do so. Let it dry.

4. Loosen the rubber bumpers on the underside of a conventional toilet seat and slide them to the side so the seat will fit flat on the box, around the bucket rim. Mark the holes where the toilet seat screws will attach to the hinged 18-inch lumber square on top of the box. Attach the seat to the box. You should be able to lift the hinged platform, including the attached toilet seat, to remove the bucket beneath it when necessary.

5. Place the box over the plastic bucket on the floor or platform in the toilet room or outdoor shed. Fill the bottom of the bucket with 2 inches of sawdust or other dry cover material. Put the container of cover material and the scoop in the toilet area. Cover is layered over the bucket's contents each time the composting toilet is used. The extra buckets are used as the others are filled and lids placed on them while awaiting removal to the compost pile.

Tips & Warnings

• When purchasing supplies, be sure to get four identical plastic buckets to switch out in the composting toilet. The hole you cut in the plywood seat must fit the bucket's rim, so having the same buckets ensures that they will all fit the custom platform properly

• Select the clean cover material--sawdust, grass clippings, straw, peat moss, rice hulls or ash--based on cost and local availability.

References

• Greeniacs Guides: How to Build a Composting Toilet
• Web Life: The Sawdust Toilet