Installation in a restricted space in a trail liner

This is already the second composting toilet that Bernhard Stroop from www.stroop-voyage.de has installed. Three years ago, he first chose the stand-alone model and installed it in his trailer. The functionality convinced him so much that he now decided to build a built-in model.

Bernhard provided me with his complete installation instructions for the dry composting toilet, which I have summarised for you here:

Since I don't have much space between the back wall and the washbasin, I made sure to install a toilet that was as shallow as possible.
Since the Kildwick company from the UK no longer exists, I found a company that still sells the components and a self-assembly kit. I still ordered in England.
In the meantime I have also found a German distributor of the parts. You save the postage of 30 pounds. It is the company www.meinetrenntoilette.de.

Solids container (no longer available)
Capacity: 23L | Dimensions: 30 cm x 29 cm x 28.5 cm
Note: Unfortunately no longer available
Alternative click here

Urine container
Capacity: 10L | Dimensions: 14.5 cm (in the middle) x 33.5 cm x 32.5 mm
Remark: Unfortunately currently out of stock
Alternative click here

Required materials and costs

The square bucket and the half-round urine canister give me a calculated depth of 45 cm and a width of 34 cm. So I ordered the self-assembly kit for 249 pounds, which was delivered within 10 days. Converted, I paid €310 including shipping.

Now it was time to measure and try things out, which I did with cardboard models.
The result was the following shopping list:

• 2 coated chipboards (shelf board, as the edges are already finished) of 30 and 50 cm width, which I cut to 30 × 46 cm and 36 × 46 cm at home.
• Plastic board white, PVC, 5 mm, 50 × 50 cm which I cut to 46 × 47 cm and bent under heat.
• Plastic angle white, 2 × 2 cm x 1 m
• 2 wooden strips 1.5 × 3 cm

The installation - interior

I filled the Thedfort's hole in the partition with a wooden panel and only provided a hole for the exhaust air. Then I screwed the wooden slats to the short sides of the 30 × 47 cm panel, flush at the bottom and spaced at the top of the top panel.
At the back and on the partition wall, I screwed on more battens in the 47 cm thickness of the top panel. I also attached the plastic angle to the rear wall.
Then I screwed the 30 x 47 cm panel to the floor and the back wall. I also screwed a plastic angle to the front, which holds the plastic panel.
The bottom and middle slats only serve to hold the inserted wall. The hole in the floor was from the old ventilation and will be closed with flyscreen. It is used for supply of air.
The urine canister is secured with a tension belt or Velcro strip that is screwed on to the right and left. The upper cover plate rests on the two side and rear strips and is pushed under the plastic angle.

For the urine canister, I constructed a lid from a plastic storage can with a diameter of 9 cm, as I did not want to make the original lid leaky by drilling a hole. I cut a large hole in the lid of the can to fit the inlet spout and drilled 5 holes in the bottom (be careful when drilling, plastic breaks easily). Without this construction, the liquid in the canister spills over. There is no replacement lid. (Note: In the meantime, replacements are available in the shop).

Here, the upper cut-to-size panel is placed on top. The two screws are used to hold the toilet seat. There is a recess on the front right and left into which the plastic plate is inserted.

The urine separator is then placed under the cut-to-size chipboard. It covers the whole board and the toilet seat lies completely on top.
The material is easy to cut and sand with multi-tools. This composting toilet I built is designed so that all parts can be removed and cleaned separately.

The installation - Visible area

 

Here the toilet seat is attached. This is not screwed on either.
The rubber nubs for the support of the seat are cut out in such a way that a recess is created for the separator and it is thus fixed. At the same time, the toilet seat presses the separator and thus the foam rubber plate at the outlet firmly onto the urine canister. Next to the toilet is the bucket for the toilet paper.

Here is a look at the finished toilet with the plastic cladding that is only plugged in. It can be easily removed to empty the urine canister.
I will add a window in the cover so that I can read the urine level at any time.

Die Entlüftung

For the ventilation, I screwed a 10 cm pipe connection onto the inner plate and onto the service flap of the Thedfort in such a way that the two ends butt together and are closed by a seal when the flap is closed.
On the flap I screwed an 8 cm PC silent fan with an output of 0.15A. The black dot on the built-in panel is the off switch (with LED) - see 1st picture under the item "Installation".
I put a carbon filter gauze in the hole that I drilled in the flap with an 8 cm drill bit and closed the hole on the outside with a 10 x 10 cm gill plate. You can't hear the fan.

Installation of an automatic agitator

I remove the stirrer from the old dry toilet. At the local blacksmith's I had this stirring hook bent from a 10 mm stainless steel rod according to my own drawing. In the motorhome forum, a member gave me a link to a motor that is powerful and slow enough. Then I chose a ball bearing with a 10 mm hole.
Then it was time to drill the holes in the bucket. Don't make the mistake of measuring only one leg of the stirring rod. The second one was 1 cm longer and I had to file the hole afterwards.

Installation of the motor

I screwed the motor onto a wooden plate and then put this on the bucket with a seal and fastened it to the bucket with two stainless steel screws. I attached a plug to the cable of the motor so that I can easily remove the bucket. The motor is connected to a circuit board that is controlled by a push-button and runs the motor for a value of 15 minutes that I have set. Addition: Since the motor of the mixer shaft burnt out on my last holiday, I connected a fuse upstream. I measured the power consumption of the motor, which was about 2A, and then installed a 5A fuse in the motor's supply line.
It should blow before the motor is overloaded.

And now here is how to secure the urine canister. A simple strap and a Velcro strap screwed to the sides and joined in the middle.

The picture below shows the ventilation to the outside - a screwed-on gill plate, 10 × 10 cm from the DIY store, provided with sealing strips and then screwed tight.

 

Here the ball bearing screwed onto the outside of the bucket, also sealed with a rubber washer and screwed tight with stainless steel screws.

Service flap - outside

I cut the corners off an 8 cm silent fan with 0.15A and got it into the pipe connection. Then I screwed the pipe connection onto the hole in the service flap, placed a grille in front of the fan and cut a carbon filter mat to size. I pressed a 3 cm flexible hose over the pipe connection as a seal. The fan is switched on with a toggle switch with LED.

Service flap - inside

First, I made a pattern again with cardboard to match the inner pipe connection exactly with the outer one. Then I sawed the hole and screwed the pipe connection onto the plate. To the right of the pipe connection is the electronic board for the motor control.
This could be bought ready-made on the internet and can be set to max. 15 min. It is connected to the power cable of the water pump of the former Thedfort.

Closing words

Bernhard's self-assembly report is a little more complex than others. However, due to the detailed instructions, it will be easy to build for most people.

If you like the instructions or have any suggestions for improvement, please write Bernhard some feedback or leave a comment here.

Bernhard Stroop has a travel blog at www.stroop-voyage.de. Exciting travel reports are waiting for you there.
Thank you Bernhard for this detailed self-build report!