What is a compost toilet?

Want to understand more about compost toilets?

Here at WooWoo Waterless Toilets, we sell several types of compost toilets and they all work in slightly different ways. Before we explore, let’s get an understanding of some of the basic terminology that will help explain the differences between them…

Martin Profile Pic

Our in-house compost toilet guru Martin, will help explain everything:

“All the toilets we sell are classed as waterless or dry toilets – this is just an umbrella term that covers any toilet that doesn’t use water. And just because it’s waterless, doesn’t mean it’s a compost or composting toilet – there are incinerating and freezing toilets too!

I’ve broken the explanations down into discussing the differences between ‘compost or composting‘, separating or non-separating , and finally, odour control“.

Compost or Composting

Although you’ll often hear people use the words ‘compost toilet’ and ‘composting toilet’ interchangeably, there is a subtle but important difference between them.

A compost toilet is typically a collection unit/container that will temporarily hold the contents that are subsequently treated or composted away from the toilet, whereas a composting toilet actually does the composting within the toilet.

A compost toilet is therefore half of a composting system (the other half being the compost bin or treatment system)

Some compost toilets, such as most models in the Separett and Air Head range, are compact and can be easily retrofitted in domestic spaces directly on the floor (no underground chambers or deep pits to be dug). However, they will need regular emptying, depending on the amount of use they get. Others, like the Kazuba range, are much larger and as such can last six months or more between any servicing/emptying, again, depending on use.

Separett Villa in luxury cabin by MWD Wales.

Separett Villa compost toilet installed in luxury cabin. Photo and cabin by Mark Waghorn Design.

Air Head compost toilet installed in a campervan wetroom. Photo and installation by Adrift Conversions.

Kazuba KL2 waterless toilet install at Cumnor

Kazuba KL2 accessible compost toilet, installed at Cumnor Parish Council.

Because they are not composting within the toilet itself, most of our compost toilets, don’t need anything added at the time of use (unlike some more traditional styles of compost toilets, which require sawdust or similar as a cover material), so they are incredibly simple at the point of use.

A composting toilet, like the WooWoo GT range, takes in the raw materials (faeces, urine, toilet paper) and facilitates the whole composting process within the toilet container. This typically means the container is much larger than most compost toilets, which might make installation and positioning more complex. The advantage of a composting toilet is that the operator or site owner is only handling compost as a final product i.e. there is no transfer of the contents (uncomposted manure) from the collection unit to a separate composting unit.

WooWoo GT LUX composting toilet with porcelain pedestal, installed at Caelal camp site

WooWoo GT LUX composting toilet. The LUX has a porcelain, non-separating pedestal. Image by Caelal camp site.

Size comparison between WooWoo GT120 and GT330 composting toilets

WooWoo GT 330 (left) and GT120 (right) composting toilets.

WooWoo GT330s installed in a custom cabin at Finnebrogue Woods

WooWoo GT 330 composting toilets installed in a custom cabin at Finnebrogue Woods. 

To facilitate the composting process within a composting toilet, a source of carbon will need to be added. This is commonly in the form of fine wood shavings that can either be added by the user at the time of use, or by the owner/operator on a regular basis.


Compost toilets in our range include:

Composting toilets in our range include:

You can also read more about the composting process here.


Urine separating or Non-urine separating

Urine separating or urine diverting is achieved through a special design of the toilet bowl (known as a urine separator or UDT – Urine Diverting Toilet). They work on the principle that when someone sits down on the toilet, urine will always go towards the front of the bowl, so it can be allowed to flow away and dealt with separately and uncontaminated from the faeces.

Having no cross-contamination means pure urine is generally sterile and can be run into the ground via a soakaway pit or a greywater drain for ease of disposal. Or, you might want to collect urine for use as a free fertiliser, diluted around 10:1 with water.

Urine equates to around 80% of the volume of ‘waste’ that the body excretes, which means that the solids (faeces) collection part of the toilet is only having to hold and store the remaining 20%, making it last longer between emptying and therefore generally easier to manage.

Air Head compost toilet showing the urine separating design.

Separett Villa compost toilet showing urine separator

Separett Villa compost toilet. The blue concealing screen hides the solids container.

WooWoo GT LUX porcelain non-separating pedestal

WooWoo GT LUX porcelain, non-separating pedestal.

The compromise with any separating toilet is that users should sit down to enable the correct separation of liquids and solids to occur. Whilst this is fine in domestic and low-use non-domestic settings, it can be open to accidental misuse, hence non-separating models are often preferred in high-use and public-facing installations.

Non-separating toilets make the user experience simpler as there is no requirement to sit down or be in a specific position. However, capturing liquids and solids together does mean the collection part of the toilet will have to be physically much larger than with a urine-separating toilet.

Separating toilets in our range include:

toilets in our range include:

Odour control

Odour control is best done through efficient ventilation, alongside other factors that all work together to ensure the user experience is pleasant and odour-free.

Some of our larger, higher capacity models (WooWoo GT and Kazuba) use wind-powered fans (and with the Kazuba, the additional benefit of the warming action of the sun on the chimney), to create an airflow that removes odours and excess moisture.

Kazuba KL2 showing ventilation 'chimney' and spinning wind vent

Kazuba KL2 features a black ‘chimney’ and a spinning wind vent for odour control and liquids evaporation

Separett Villa ventilation options

Ventilation options for a Separett Villa (Tiny is very similar).

WooWoo GT natural ventilation system

WooWoo GT uses 110mm pipe for ventilation and can be fitted with a spinning wind vent or an electric fan.

Smaller toilets, such as Separett and Air Head use low-power, low-voltage electric fans to pull or push air through the vent pipe to the outside, removing odours and excess moisture.

With the WooWoo GT, the action of naturally occurring, odour-eating compost bacteria is encouraged through the design and function of the toilet, together with the addition of a carbon-based cover material that will eliminate most of the foul odours naturally, with the balance removed through the ventilation system.

Remember – the ventilation system is not only removing odours, it’s also dealing with moisture too.


Take a look at these animations for a good overview on how the systems work…

See how a Separett, urine-diverting toilet works.

Kazuba STK work by allowing liquids to drain through to an evaporation plate. Play the video for more details.

So that’s it – now you know the basics of how waterless toilets work!

If there’s anything you’re not sure about, why not call us? One of our friendly team will be happy to explain anything you need and offer our best advice for your situation.