Chemistry out - Nature in

Conversion: composting toilet instead of cassette toilet

Ecki and Kathrin from Coaches on Tour have provided us with a very detailed self-assembly report of a dry composting toilet.

Like almost all motorhomes, they had installed a cassette toilet from Thetford. Of course, this had to be removed first. They also made a video about the detailed report on the conversion of a cassette toilet, which we would like to recommend to you.


  • Self-Assembly Set #3 XS
  • Remark: No longer available - Alternative SB1 - Self-Assembly Set for composting Toilets
  • 18 mm multiplex panels
  • 12 V fan
  • Gill plate

Cassette toilets conversion - composting toilets report:

Ecki writes the following about the conversion:

After we had originally wanted to install a NaturesHead, we then decided to build our composting toilet ourselves...

But let's start at the beginning.
We had decided to dissolve our flat and move into a mobile home - less is more.

To experience and enjoy simplicity. After travelling with our VW T5 for five years, we took the next step.
Not an easy step, of course, but it was the right one for us.

Umbau Kassetttentoilette

We decided on a motorhome because we realised that there was enough space for us in it and we also didn't have the time and opportunity to extend a van ourselves, which was the original thought...

For us, it was clear from the beginning that we wanted to have a composting toilet. Since chemistry is not an option for us and we also wanted to be more self-sufficient, we initially decided on a NaturesHead.

But when we realised during the planning phase that the template was too big for our Gustl - the name of our motorhome - we had to come up with another solution.

So we thought and planned to buy a kit and build the whole thing ourselves.

No sooner said than done, we got the kit #3 XS (no longer available, alternative self-construction kit SB1) from Markus Becker of and started planning and then building.

Umbau Kassettentoilette

Installation of the separating insert in the TTT cover

Kassettentoiletten Umbau

TTT lid with hole for the divider insert and the self-made toilet seat and lid.

Do you also need a do-it-yourself set? Here you will find our entire selection of do-it-yourself kits.


Or: View overview of all self-assembly sets

The construction timber for the box is 18 mm Mulitplex. We had this cut to size directly at the DIY store.

We also had the construction for our washing machine cut from the rest of the board, so we had everything in total.

In this video, Ecki and Kathrin from Coaches on Tour explain all the important conversions and how to use the composting toilet.

Watch it, as all questions are clarified here. I'm sure the two will be happy about a comment and a like.

Eckhart continues to write about the conversion of his cassette toilet:

In the end, it was a lot of work with measuring, planning, trying, thinking and then the actual construction, but we are currently satisfied with our solution.


Of course, we have also installed an extraction unit, but it is not a continuous extraction unit like others, but we have connected it to a toggle switch - which previously activated the lighting in the supply flap - and so we can switch it on and off as needed.
Umbau Kassetttentoilette

To do this, we had to drill a hole and fit a ventilation grille in the existing supply flap from the original Thetford toilet.
We converted the existing water hose into an outdoor shower by installing a quick-release coupling. The toggle switch that we installed instead of the water flush switch of the former Thetford toilet now activates the water pump for the shower.


After more than 4 months of use, we are totally satisfied and happy to have installed the composting toilet. There has never been a problem with either use or disposal.

Many thanks to the two from Coaches on Tour for the detailed self-build report including video. Converting a cassette toilet is often a challenge at first. We are therefore very grateful for every single self-build report.

As always, we look forward to your comments!

PS: You can also find ready-made composting toilets in our shop.