How to Build a Solar Composting Toilet
If you've been thinking about buying or renting a portable toilet for use in the field, consider building a solar composting toilet instead. Solar composting toilets work by converting human waste into nutrient-rich compost that is suitable for most gardens and small farms. You may want to avoid using human waste compost on root vegetables where the actual food comes in contact with the compost, but it is a great fertilizer for trees, bushes and flowers. Solar composting toilets are cleaner than a conventional portable toilet, and the compost has no feces smell at all. Does this Spark an idea?
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Things You'll Need
- 2 foot by 4 foot by 1 inch laminate board
- Toilet seat
- Pencil, pen or permanent marker
- 4 4 inch by 4 inch pressure treated posts cut to 4 foot lengths
- 2 1 inch by 1 inch by 22-inch boards
- 2 1 inch by 1 inch by 40-inch boards
- Wood glue
- Jigsaw
- Power screwdriver
- 8 inch wood screws
- 1 1/2 wood nails
- 2 to 4 50 gallon plastic storage bins with lids
- 5 gallon bucket
- Sawdust
- Pitchfork or shovel
Instructions
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Build the Toilet Structure
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1
Lay the laminate board on a solid, level surface. Set the toilet seat on the board where you will eventually secure it. Use a pencil, pen or permanent marker to trace the inside of the toilet seat.
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2
Position the four posts at the corners. Use wood glue to secure the posts to the laminate board. Position the 40-inch boards along the long edges of the laminate board, between two of the 4-inch posts. Use wood glue to secure them to the laminate. Allow the wood glue to cure according to manufacturer's instructions.
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3
Position the 2 22-inch boards 3 inches on either side of the cut line. Brace them between the 40-inch boards and glue into place. Allow the wood glue to cure according to manufacturer's instructions.
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4
Use the jigsaw to cut a hole in the laminate along the cut line.
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5
Turn the structure right side up. Use the power screwdriver to drive an 8-inch screw through the laminate and into each corner post. Use 1 1/2-inch screws to secure both 40-inch bracing boards and both 22-inch bracing boards to the laminate. Following manufacturer's instructions, screw the toilet seat to the laminate.
Using the Composting Toilet
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6
Slide one covered plastic storage bin under the structure you built. Store the other in an out of the way place. Fill the 5 gallon bucket with sawdust and place it near the toilet.
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7
Before using the toilet, uncover the plastic storage bin and make sure it is positioned under the toilet seat hole. After using the toilet, cover the waste with sawdust to soak up any liquid and to eliminate odors. Cover the plastic storage bin.
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8
Every few days, use the pitchfork or shovel to turn and mix the waste in the storage bin.
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9
When the bin is full, replace it with an empty bin. How often you have to rotate bins depends upon your level of use. Place the full bin uncovered in a sunny location to finish composting. You can also dump the partially composted waste into a dedicated compost pile. The sun will heat the compost and speed the decomposition process. Use the pitchfork or shovel to aerate and turn the compost every two weeks. This will also speed the decomposition process and eliminate odors.
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Within six to 12 months (depending on how much solar heat and aeration the compost receives) you will have fully decomposed compost.
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Tips & Warnings
You can also build an outhouse style building to house the solar composting toilet. If you choose to do this, use cedar paneling on the interior. The cedar will prevent odors and discourage insects.
Be sure to use plenty of sawdust when you use the toilet. It should soak up any liquid and fully cover the waste. This will prevent odors and add valuable carbon to the finished compost.
