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Composting Toilet Plans
The following plans will help you build a composting toilet that is odorless, incredibly easy to use, fully-functional, and portable. That last point is probably one of the most common reasons why people build a composting toilet in the first place; they're looking for an inexpensive way to dispose of human excrement in a remote location (e.g. cottage or cabin).
Before You Begin Building...
First, in order to use this composting toilet properly, you're going to need an outdoor composting bin system. See bottom of post for more information
Second, these composting toilet plans call for the use of cover materials. Cover materials are just that, they are the materials you will use to cover your waste once you have used your toilet. A variety of materials can be used for cover, including sawdust, peat moss, cured compost, leaf mold, and/or rice husks.
An ideal cover material is highly biologically active (i.e. high in microbial activity). The more active this material, the better it will be at absorbing odors from your compost toilet. Please note that I do not recommend sawdust from woodworking shops, since this material is completely dry and devoid of biological activity. Instead, when I say sawdust, I am referring to the waste product from sawmills. This type of saw dust is still moist, rich in microbes, and partially decomposed; all of which make it a great cover material.
What You'll Need
To successfully use these composting toilet plans, you will need the following materials:
4 identical 5-gallon buckets
1 18"x18" piece of 3/4" AC fir plywood
1 18"x3" piece of 3/4" AC fir plywood
2 10"x18" pieces of 3/4" AC fir plywood
2 10"x19.5" pieces of 3/4" AC fir plywood
4 3"x12" piece of 3/4" AC fir plywood
2 metal hinges
1 standard toilet seat
Jigsaw
Drill
30+ 1-1/2 screws
Wood glue
What is AC fir plywood?
Softwood comes in a variety of grades (A through D). Each side of the wood is graded according to the number and severity of knots, splits, and other defects. Grade A is the best, whereas Grade D is the worst. So in this instance we are recommending one side of the plywood be Grade A (the fir side), and the other side be Grade C. This is one of the most common grades of fir plywood, so you shouldn't have a problem finding it.
Instructions
Step 1
Assemble the frame of your toilet. The finished frame will be 21" long, 18" wide, and 10" deep. Begin by attaching the two 10"x18" pieces of plywood to the two 10"x19.5" pieces of plywood, using screws and wood glue. Be sure the 10"x19.5" pieces fit inside the other two pieces for a total length of 21". Also, be sure the fir side of the plywood is facing out.
Step 2
With the frame in the upright position, place the 18"x3" piece of plywood on top, and line it up with one end of the frame. Again, be sure the fir side of the plywood is facing out. Now attach this 18"x3" piece of plywood using screws and wood glue.
Step 3
Place the 18"x18" piece of plywood on top of the frame in front of the 18"x3" piece you just secured. These pieces will eventually be attached together using the hinges, however, you must first cut out the hole for the bucket. Be sure the fir side of the plywood is facing out.
Position the bucket 1.5" from the front edge of the box, and center it from both sides. Draw a circle around the bucket's edge to indicate where you will be cutting it. Remove the bucket, and use the jigsaw to cut the hole for the top of the bucket.
Step 4
Now that the hole has been cut, reposition the 18"x18" piece of plywood on top of the frame. Using eight screws and the two hinges, connect the 18"x18" piece of plywood with the 18"x3" piece. Be sure to position these hinges close to the edges of the toilet, so that they don't interfere with the toilet seat.
Step 5
You will now attach the legs (four 3"x12" pieces of plywood) to each corner of the underside of the frame. It is very important to adjust the length of these legs, so that the top of the compost toilet is positioned 1/2" below the top of the bucket. The bucket should protrude through the top of the toilet by 1/2". This will ensure a tight-fit, and prevent any waste from missing the target. This is especially important if children will be using your compost toilet.
Step 6
The next step in these composting toilet plans is to attach the toilet seat. Before doing so, you will need to reposition the bumpers that are found on the underside of the seat. Typically, these bumpers point inwards, but this will interfere with the bucket, you so have to swivel them sideways (almost parallel to the toilet seat edge).
Position the toilet seat over the bucket, and mark where you will need to drill holes to attach it to the frame. Drill these holes, and attach the toilet seat.
Step 7
Your new compost toilet is now ready to use. Although, to make it's appearance a little less rustic, you may want to stain, varnish, or paint it.
The previous composting toilet plans were adopted from Joseph Jenkin's incredible book The Humanure Handbook. If you have any interest in learning more about this subject, I highly recommend reading his book (it's free online).
When composting human manure, you typically use a continuous method of composting. Continuous composting refers to continuous addition of small amounts of composting materials to your pile. Compare this to batch composting, in which all of the materials to build an entire compost pile are added at one time; when this occurs, compost is said to be made "one batch" at a time. Due to this continuous method of composting, I recommend you build a three-bin compost system.
Remember, you'll want to have this compost bin system in place prior to composting your human waste.
To begin the composting process, you'll want to add 16"-20" of coarse carbon material (e.g. straw, hay, leaves, sawdust, shredded newspaper, yard waste) to the bottom of the bin on the far left. This layer acts like a sponge, to help soak up any liquid that may try to seep from your pile. Next, you can add you first couple buckets of human excrement. Cover this waste with more coarse material.
Continue with this type of layering procedure until your first compost bin is full. Typically, this takes anywhere from 1-2 years, depending on how many people are using your portable composting toilet. Be sure to use all of the principles of good composting found here.
Once full, you're going to want to leave the contents of this bin to digest (undisturbed) for an entire year. Allowing this pile to sit, undisturbed,
for one full year will destroy
all of the potential pathogens.
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Thank you for taking the time to read this post and I hope it has assisted you with the construction of your compost toilet.
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Regards
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THL
.Link to more information http://www.compostjunkie.com/composting-toilet-plans.html