How a composting toilet works

Function and construction of a composting toilet

This article is interesting for you if you want to know:

  • how a composting toilet (dry toilet) works,
  • why it doesn't need water or chemicals,
  • is good for the environment,
  • it doesn't stink,
  • it's easy to dispose of,
  • and who it is suitable for┬á

Construction of a composting toilet (dry toilet)

Now it's time to look at the inner values of a composting toilet. What does the composting toilet look like from the inside and how does it actually work as a composting toilet or dry toilet?

--> Do you want to build a dry composting toilet yourself? Here you can find kits for your project. (Please click)

The principle of a composting toilet

A composting toilet separates your urine from your solids.

And it does this in a very simple way: With the so-called urine separator.

This separates your excrement. Mixing, as with a normal toilet (WC or chemical toilet), is avoided.

In addition, both are collected separately in the composting toilet. The solid matter in a bucket, the urine in a canister.


The difference between this and a "simple" dry toilet lies in the separation of the two. In a simple dry toilet, both are put together in one container....

The composting toilet basically consists of only 3 main elements:

  • the urine separator (separating toilet insert)
  • the solids container (bucket)
  • the urine container (canister)*.

*The latter can also be replaced by a hose to drain the urine into a larger tank.


In addition, you will of course need an appropriate box and a toilet seat. ­čśë

Important: to ensure that the separation of your excreta works well, you must use the composting toilet in a sitting position. Otherwise, proper separation in the composting toilet is not guaranteed.

This is because the urine separator is anatomically designed for a sitting person.

--> --> Click here for an overview of all available dry composting toilet kits (please click!)

Why does a composting toilet require no water?

In this case, a composting toilet is also always a dry toilet. This means that it does not need water for flushing.

Your solids fall directly into the solids bucket due to gravity without touching the urine separator. The bucket is also used to dry and store your stool.

The urine is fed through the funnel-like design of the composting toilet insert at the front into the urine canister or with a hose into a urine tank.

Here, too, you don't need water for flushing.

The big advantage here is that with a urine-diverting toilet you don't waste precious drinking water for flushing, which you have to dispose of afterwards.

A composting toilet does not need chemicals

Because you separate your solids and urine, you don't need chemicals!

Why is that?

The chemicals in chemical toilets are not primarily used to decompose your excrement, but to " fragrance " the resulting stench.

Because it is only when urine and faeces are combined that the odour nuisance you are familiar with occurs.

A composting toilet does not smell

Urine (normally) does not smell by itself.

And neither does your stool when it is dry!

This is the principle behind the composting toilet. By separating the solids in the urine-diverting toilet, they can dry out more quickly.

You can speed this up either by adding a litter or by stirring and using a stirring insert. And this is done in a natural way, without any environmentally harmful additives.

With this method, you can completely do without chemical or other odour-intensive additives.

Overview: All composting toilets

How does disposal work with a composting toilet?

It's simple! You have two things to dispose of

  • Solids (possibly with litter).
  • Urine

Both are of natural origin. This means you don't have to worry too much about disposal.

You can either dispose of your solids in your compost* (if you have one) or simply add them to your normal household waste.

The urine can also be diluted and used as fertiliser* in your garden. Alternatively, it can be poured down any toilet.

What this means for you is that with a composting toilet you no longer need special disposal stations for your waste disposal. Because you don't have a lot of black water any more.

This will reduce the amount of waste you have to dispose of by up to 80%!

*(please also note the regulations of your municipality and whether you are taking medication that would prevent composting).*

For whom is a composting toilet suitable

I always say: the composting toilet is the toilet of the future. It saves resources and is sustainable.

Ideally, the composting toilet is something for you if you:

  • travel a lot with your motorhome / caravan
  • have a garden shed without a sewer connection
  • use a weekend house without a sewer connection
  • live freely in nature in a Tiny House
  • want to use a toilet on a boat
  • and if you are tired of always having to look for or drive to a disposal station after 1-2 days just to be able to dispose of your toilet.


As I said: a composting toilet needs no water and no chemicals. And the disposal is very simple!

Build your own composting toilet or buy a ready-made one

I hope I have been able to explain you the functioning and advantages of a composting toilet to you.

Basically, a composting toilet is not rocket science.

It is a principle that has been tried and tested for decades. It is also frequently used in the Nordic countries (e.g. in weekend houses in Sweden and Norway).

And as simple as the principle is, a composting toilet is also easy to use.

With a little manual skill, you can easily build a composting toilet yourself and adapt it to your circumstances.

Here you will find a number of do-it-yourself reports. Just let yourself be inspired!

However, there are now also a number of beautiful prefabricated composting toilets available for purchase. Whether for the garden house, weekend house, Tiny House or mobile home.

Here you will find an overview of the most popular composting toilets and an overview of all kits. 

My conclusion on the composting toilet

In my opinion, the composting toilet is a great alternative to many other types of toilets. Particularly in remote places or in the motorhome and on your boat, the composting toilet shows its advantages.

Yes, it needs a little "care", but it is far better than any chemical toilet.

I hope I was able to give you a better understanding of the composting toilet. Maybe you are also thinking about a composting toilet. I would be pleased ­čśë .

By the way, there are more articles here on the blog that might interest you:

  • The best composting toilet inserts (comparison)
  • The most popular composting toilets (comparison)

Discuss with me here at the site!


Is there anything you are particularly interested in?

Please leave me a comment or write to me directly.

Your Markus from MeineTrenntoilette.de

PS: Download the guidebook for composting toilets here.

Important links:

  • To the urine separator
  • To the kits
  • To the composting toilets