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Composting Toilet

Making your own composting toilet is easy, ecologically friendly and requires no plumbing.

Human waste can be one of the most dangerous sources of contamination on any homestead, or municipal. It has many pathogens, beyond those in most animal manures, that should be destroyed, not allowed to breed in a nice, cozy, wet tank underground.

With a compost toilet, you know exactly where things go. You can monitor the system, make changes if needed, and enjoy the responsibility of disposing of your waste properly. No septic system owner can say the same.

Humanure also makes excellent compost and is a great water saver. Flushing that toilet wastes an enormous amount of good drinking water (over 50 gallons per person per day in the USA). If you are interested in this subject, a must-read book is Humanure by Joseph Jenkins.

Step 1: Design

Decide upon the design of your toilet and what you want/need before you start.

We built a container for sawdust and a two-bay toilet, so that one day we will be able to separate our feces and urine. Urine has its own use beyond composting. For example, it is great for trees, especially if you pee on bio-char, which absorbs the nutrients and releases them slowly. For the time being, however, while our kids are young, we have one adult toilet and one with an infant seat.

We also built arm rests into the unit. We figured that these would help the kids when getting up and are also invaluable in the case of injury, to be able to lower yourself down onto the seat.

We chose to build our toilet out of 2″ x 2″ lumber and 1/2″ plywood. We then painted it all to protect it and make it easier to clean.

You can use wood, metal or even concrete.

You’ll also need a bucket or container and a toilet seat.

 

Step 2: Toilet
  1. Make a frame out of 2″ x 2″ lumber. Its outside dimensions should be 42″ wide, 18″ deep and 18″ tall. It should have three sets of uprights and across pieces, on the two ends and in the center (in between the two bays).
  2. Attach 1/2″ plywood to the sides, back and front of the unit. Not the bottom or top.
  3. Attach a 2″ wide strip of plywood on the top of the unit along the back.
  4. Attach three 2 1/2″ wide strips of plywood the top, one on each side and one in the middle.
  5. Cut two pieces of plywood, each 17″ by 17″.
  6. Place a bucket upside down on each piece, centered side to side, but so that one edge of the circle is 2″ from the front of the piece of plywood. Draw a line around the bucket and cut it out with a jigsaw.
  7. Attach two hinges to each piece of plywood and then attach those hinges to the strip of plywood on the top at the back.
  8. Screw a toilet seat into each hinged plywood piece.
  9. If you wish arm rests, you may add them.
  10. Paint the whole thing, inside and out with a acrylic paint.
  11. Set the unit up where you wish it to be.
  12. Lift the hinged plywood up and put two five gallon buckets inside, under each hole. Put bricks or wood or something under each bucket to raise it up to the same level as the plywood lid. We used the circles that we cut out of the top plywood, and put them on legs.

 

Step 3: Solar air vent

When we were designing our bathroom, we incorporated a solar air vent that went from the inside of the composting toilet unit to the outside. The toilet doesn’t really need it, so don’t worry if you don’t want to do one. But it was so easy to do as we were building that we thought why not.

Inside
  1. Before laying the floor of your bathroom, dig a trench from the center of where your toilet unit will go to the outside of the house. The trench should be deep and wide enough for a 4″ PVC pipe and should slope gradually from the toilet to the outlet. [Alternatively, you can make a hole in your wall, angled from inside the toilet unit to the outside.]
  2. Place a piece of 4″ PVC pipe, the length you need from toilet to outside (use couplings to join two lengths together if necessary) inside the trench.
  3. Place an elbow on the toilet end of the pipe, and to it attach another length of pipe, so that it will just clear the floor.
  4. Fill in around the pipe with dirt.
  5. You can now make your bathroom floor.
Outside
  1. On the outside end of the PVC pipe, attach an elbow.
  2. To the other end of the elbow attach a 10 ft piece of 4″ PVC pipe, on top of which place a T.
  3. Paint this pipe and T black.
  4. It’s not a bad idea to guy this pipe down, so that the wind can’t blow it around.

The black pipe will heat up in the sun, causing the air to rise. As it rises, especially as it is so tall, it will create a pull on the air inside the toilet unit. When the sun is shining, you can place your hand over the pipe inside the toilet unit and feel the pull.

 

Step 4: Cover material

After each use of the toilet, you’ll need to sprinkle a cover material, like sawdust or peat moss, into the bucket.  Personally, we prefer sawdust. We find it takes away the smell more effectively, and is readily available to us.

The cover material helps absorb moisture, and adds to the decomposing process by balancing carbon material to your nitrogen. It therefore helps to have a container near your toilet to hold the cover material.

  1. Using 2″ x 2″ lumber, make a frame with outside dimensions being 23″ wide, 18″ deep and 24″ tall.
  2. Attach plywood to all four sides as well as the bottom.
  3. Cut a 1 1/2″ wide strip of plywood and attach it to the top of the unit at the back.
  4. Cut a piece of plywood 24″ wide and 17 1/2″ deep.
  5. Attach hinges to this lid and to the strip on top at the back.
  6. Paint inside and out.
  7. Fill with cover material and place beside your toilet.

 

Step 5: Compost bin

Once the bucket gets filled up, you’ll need to empty it into a compost bin. The pile method is great for almost all of your other organic waste, and especially all of the organic matter from the garden, but we do not recommend it for composting humanure. For that, it is best to use a separate bin, and let it sit longer, just to make sure it gets broken down and also to give the bacteria ample time to eat any bad stuff that might be in there, like worm eggs, parasites, or harmful pathogens.

The bin that we use for humanure works great and is easy to build. We have three of them. By the time the last is filled, the first is fully composted and can be emptied wherever you need the soil enriched.

  1. Decide on a location for your bins. Do not put them uphill from any gardening area, so that rainwater does not leach uncomposted material onto your food source. The area around your bins grows grass thicker than anywhere else, so you can place them somewhere you will one day plant, thus enriching the soil for future use.
  2. Take two 8 foot long pieces of lathing and/or remesh, and tie the two ends together, making a closed circle.
  3. Line this circle with mosquito netting, so that flies cannot get into the bin.
  4. Put rocks around the outside of the bin, at the base. This helps keep dogs from trying to dig into the material, as well as keeping the base in place.
  5. Tie a piece of lumber across the top of the circle, over to one side. As you empty buckets, it helps to have something to bang the bucket against, to get all of it out.
  6. Make a lid to fit the circle. You want it light-weight, so that it’s easy to lift off. We use remesh, with mosquito netting attached to it.
  7. Each time you empty the bucket, throw it onto a different place inside the bin, so that it fills up evenly.
  8. Wash the bucket well, and dump the wash water onto the bin as well. Humidity in the bin will help it compost faster.
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