Thursday, April 16, 2020

New Composting Toilet Build and Install (with Improvements) Pt. 2

So having finally ripped out the old blackwater system from Constellation, we braved the virus to go get some parts and put together our new composting toilet.  If you'd like the basic design and construction, you can find our pamphlet on the thing HERE or check out our earlier build on the blog HERE.

You will need:
Two, 5 gallon buckets.
Some 1/2" ID tubing
A right angle fitting for the tubing
Some very short stainless steel (trust me) screws
A "Luggable Loo" or other snap on seat for bucket toilets.

While you can do this with a knife, I strongly recommend using a jigsaw with a PVC cutting blade.  It will make VERY short work of this project and save you a lot of frustration.  It's also quite a bit safer.  You'll also need a 3/4" bit to cut the opening for the fitting in the urine diverter.

Okay, ready?  Here we go with the basic construction.

First, cut the top part off of one of the buckets.  Typically these things have two built up bands that re-enforce the top rim.  You want to be about three or four inches below that, about eight inches or so below the top rim.  You'll need to remove the handle.

Here's the cut of top of the bucket with the urine diverter in place.  Notice my elegant and regular cut.. .  .not.
 Cut across the bottom of the bucket just short of halfway and cut an arc from that out of the sides of the bucket to make this kind of wedge shape.  There are some more detailed photos of this piece in our original article HERE.

Here's the wedge shaped cut from the bucket bottom that comprises the urine diverter.  This is where to drill the hole and screw in the fitting.

Drill a hole in what will be the new urine diverter next to the edge of the bottom and screw in the pipe fitting.  In the photo above, the fitting is a straight one with a 1/2" barb connector for the tubing.  I changed that for a right angle fitting, which prevents the hose from kinking quite so easily.

Screw the diverter wedge in at a slight angle a couple inches below the rim (it has to clear your bum after all).  The fitting, obviously, has to be at the lowest point.  

Screw your diverter in a couple of inches below the rim at an angle, so it forms a "V" with the pipe fitting at the bottom.  Note, you'll need some pretty short screws or be willing to cut them off, and this process will slightly deform the bucket.  That's okay, it'll flex more than enough to still fit into the lower bucket.  Go ahead and attach a couple of feet of your tubing.  You can always trim if off later.

Now here comes the new bit.  We cut a groove down about five inches in the side of the lower bucket for the tubing to set into.  Like this:

Notch the lower bucket out like this.  The groove should easily accommodate your tubing.

Put in your liner (we use biodegradable trashbags).   Push the liner down into the little groove you just cut out.

Push your liner down into the cut.  The tubing will sit in this groove.
Now put the top part with the urine diverter onto the lower bucket.  The groove you cut should be on the side and the diverter to the front.  Putting in a bit of sawdust or wood stove pellets (which is what we use) at this point will help hold the liner down and in place.

Tidy, hunh?  feel free to trim off the liner bag if you dislike the aesthetics, but I like having the excess to tie off when dumping the compost.

Now put your tubing in a container (we used a cat litter container, but anything that's short enough to be below the diverter will work).  Trim the hose as needed.  In a permanent, on shore installation, you can leave your tubing long and just run it into a dry well or into the garden (most plants will love the nitrogen).  Try to avoid kinking the hose as this will make the thing drain rather slowly.

It makes a rather tidy installation. 

Now, snap on the seat and give it a try., really.  You'll need to make sure the back of the urine diverter doesn't hit your butt.  If it does, you can either rescrew it on a bit lower or take a pocket knife and cut down the back a little.  Once you're sure the back of the urine diverter doesn't touch you when you're sitting there, you're done.

This entire thing takes about a half-hour to build, works beautifully, will last for literally years, and costs about $30 to put together, less if you have the buckets.

Next up, I'll be making a mount to secure the thing in place.

Stay tuned



  1. Hello,I,was wondering what type of fitting you used and the tubing if u can give links it would be good

  2. I believe the Lowes numbers of the ones we used are probably Item #2400743Model #32803 for a five pack. That'll at least give you an idea of what you're looking for :)