Wednesday, 10 February 2016

Build yourself a simple compost toilet

Exploded view of compost toilet
This blog is giving some more detail to the compost toilet I described in the February Organic NZ magazine.So good on you for taking the plunge-ooh that's a bad metaphor when talking about toilets..You should be able to make this with minimal skills but get someone who can help in that area if you get stuck.There are a few tools you might not have.

Tools you'll need:
  • Skill saw or table saw
  • Electric drill eg Battery drill
  • Jigsaw or coping saw (small handsaw for cutting curves) for cutting out the hole in the seat
  • a handsaw
  • Sharp chisel, around 25mm/1 inch
  • 1 sheet 2400 X 1200 plywood 18mm thick. I wouldn't use treated cause its toxic as.Its up to you.
  • A pile of 40mm length square head 8 gauge woodscrews
  • 12 woodscrews length 12mm for the hinges
  • Commercial toilet seat-I picked up our nice wooden one for 10 bucks at the local second hand shop.
  • 2 hinges for the top-50mm butt hinges. Brass is better as it corrodes in there.
  • 20 litre bucket (with lid!)
  • Optional PVC vent pipe minimum diameter 80mm and fittings so that it can go through the roof ie cap and flashing to stop leaks where the pipe goes through the roof.
  • PVA glue
Size of plywood bits:
Back and front 600mm width X 430mm height
Sides 600 width X 430 height 
Base 564 X 600
Top lid 650 X 630 

I've based these measurements around a standard 20 litre bucket, which is 400mm high.Put the sides together with glue and screws.You may need to use a small drill bit (slightly under the diameter of the screw). Use 4 screws per edge. Turn the 4 assembled sides upside down and insert the base. Glue and screw that in place. Now the tricky part is cutting out the hole for the lid. The bucket needs to be as far forward as possible, close to the front-this is primarily for the guys trying to aim and it not being to far if you get my drift. using the bucket draw around it on the lid, close to the front; 50-60mm from the front lip of the lid.Then draw around the toilet seat. And finally draw a slightly smaller circle (about 20mm smaller). Your lid should look like the birds eye view shown below. Using a jigsaw cut that hole out.

The hinged lid. 
Ok so the lid can be hinged so that you lift it up to change buckets. You will need to cut in the hinge so that its flat on the top edge of the box, like I've shown in the diagram above. This means the lid will be flat when its shut-pretty important for smell, flies etc.You will need a coping saw and chisel to cut out that notch.The hinge should be about 50mm from the edge of the box. 
You want the hole in the lid to be smaller than the bucket so that everything actually goes in the bucket! 
I also cut the top off a stainless steel bowl I got at the warehouse. This made a sort of flange which bridged the gap between bucket and lid. You don't need to have this bit- you need a grinder to cut the stainless steel- but thought I would mention it as it makes it a bit more hygienic and easily comes out for cleaning.You can remove the rubber stoppers from under the toilet seat lid if you want a tighter fit -for smell reasons. I haven't and its ok, as I said in the article I hope to fit a vent to the toilet soon. In the meantime I light a match and then sometimes burn an oil burner with lavender essential oil.
An alternative to the hinged lid is just a lid which is removable-you will need to glue or screw small blocks to the underside of the lid which locate the lid and stop it moving.
Righto, its time to decorate it with decoupage photos of your family, or cut up National Geographic pics or acrylic paint or whatever.
Other notes
Other buckets could be used-The ones Matt uses are recycled in Otaki. They are much more squat and wide. In which case you need to build up the base with strips of wood you may have left over or lying around. 
If you get confused by my instructions, give me a comment on this blog and I'll try to clarify.
I'm a non linear thinker so the instructions order may be a bit jumbled. 

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