Why don’t our compost toilets smell?

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A well designed, correctly installed and maintained compost toilet will not smell.

However, some people may have memories of a smelly, horrible experience with ‘festival’ compost toilets from years ago – thankfully, things have moved on, even if the rain and mud hasn’t!

There’s also a lot of strong (and often wrong or misinformed) opinions online – some people say that you must separate the liquids and solids or it will smell, but that’s just not true. Every situation may one or several approaches and solutions – the right one will depend on a range of factors.

So why don’t the toilets that WooWoo have chosen smell?

There are lots of different ways that you can manage the odours from a compost toilet, and the best way will depend on lots of factors, including;

  • Availability of electricity (to run an extraction fan, for example)
  • The frequency and amount of use expected
  • The type of use (for example is it used by a couple or family, or is it semi-public like a golf course or allotment, or is it at a public site)
  • The intended location (is it near a water course for example)

This is why it’s a good idea to call or email one of the experts here at WooWoo – we can ask you the right questions and help guide you through the options to come up with the best solution for your site, taking all aspects into account.

So let’s have a look at the various products we sell and the features they have to ensure they are odour-free and provide a pleasant experience for the visitor! Each solution has a slightly different approach to keeping the user experience as pleasant as possible.

Separett Villa & Separett Tiny

Both the Separett Villa and Separett Tiny use the principle of urine separation to provide the initial management of odours. This is achieved through a specially designed toilet bowl that prevents the urine and faeces from mixing.

Pure urine is generally sterile as it leaves the body, and depending on the amount of use you expect, it may be possible to run the urine out of the toilet and into the ground via a soakaway pit or leachate drain. The Separett Tiny has the choice of a model that captures urine in a container (to be emptied daily) or runs the urine out to the ground or to an external container.

We have more information on dealing with urine in the info section of the website. You can also get a general overview on urine-separating toilets on the ‘what is a compost toilet?‘ page.

By removing the urine, the odour from the faeces and toilet paper is much reduced, and is easier to deal with, and in addition, the overall volume of the remaining ‘waste’ will be significantly reduced.

Both the Separett Villa and Separett Tiny hold the solids in a container within the toilet, and utilise a well designed and efficient fan and ventilation system that continuously draws air over the solids and takes all odours out through the vent pipe. Once outside, they will quickly dissipate in the air. Opening the toilet lid will not expose the user to any odours.

Neither of the models require the use of any cover material (sawdust or wood shavings) and rely on urine separation and the fan for odour control, which makes them simpler to use.

The downside to a bowl-based urine separator is that people will need special instructions – specifically that men need to sit down to urinate and ladies sit down fully, and possibly a little further forwards than they are used to. This is to ensure the separation of liquids and solids occurs fully and correctly. There must also be some electricity available to run the extraction fan, although this can be a 12v supply from a solar panel, or mains if available.

Urine separating toilets are generally recommended in domestic and lower use situations where space is at a premium.

Separett Villa & Tiny: summary

  • Use a urine separator in the toilet bowl to make managing the ‘waste’ much easier
  • Are generally quite compact and can be installed in small spaces
  • Use a small electric fan to remove all residual odours
  • Users may need to be given specific instructions on how to use
  • Recommended for low use or domestic installations
  • Separett Tiny with urine container is ideal for mobile users (motorhomes and boats)
  • Separett Villa has a larger capacity solids container

Further links for Separett products:

Separett Villa
Separett Tiny with Urine Extraction
Separett Tiny with Urine Container

Air Head compost toilet

The Air Head compost toilet is broadly similar to the Separett Villa and Tiny in that it uses a special design of bowl to enable urine separation. Unlike the Separett models, it also adds a carbon-based medium (usually cocoa coir, added only at the start) in the solids container.

After each use, the user turns a handle on the side which mixes the deposits with the coir etc. This aerates the contents (which encourages good bacteria in, that will also reduce the odour), and coats everything in coir, helping to lock odours in. A low powered fan gently draws the foul air out.

As with other urine-separating toilets, the potential downside is that people may need special instructions in terms of their position using the Air Head toilet. There must also be some electricity available to run the extraction fan, although this can be a 12v supply from a solar panel, or the 12v circuit in your motorhome or boat.

Air Head: summary

  • Use urine separation to make managing the two types of ‘waste’ much easier
  • Uses a carbon material (cocoa coir) at the start and a mixing system to promote aeration and drying
  • Is very compact
  • Use an electric fan to remove all residual odours
  • Users may need to be given specific instructions on how to use
  • Removable urine container makes it ideal for mobile users such as motorhomes and boats

Further links for Air Head products:

Air Head with standard seat
Air Head with compact seat

WooWoo GT composting toilet

The WooWoo GT is a batch composting toilet and differs from the previously discussed products (Separett and Air Head) in that it doesn’t separate the liquids and solids at the point of use. It is a ‘proper’ composting toilet, in other words, the contents actually compost (break down into a safe, non-odourous medium) within the container.

We generally sell them as a starter pack that includes two containers – one ‘in use’ whilst the other one ‘rests’ and continues composting the contents. Therefore, when it’s time to empty the container, you are handling a safe compost, not a manure. There’s an optional porcelain pedestal (the GT Lux) for installations with enough clearance under the floor.

The container is designed to provide and maintain the ideal conditions for composting to take place, and once the compost bacteria (they are naturally in the air) take hold, the odour will be massively reduced as they act as a bio-filter.

Residual odours are taken away by the wind-powered spinning vent (or optionally an electric fan if the unit is installed within a dwelling or in an area that lacks enough wind).

Up to 90% of the liquid (urine) entering the system is consumed by the composting process, and the addition of woodshavings also act as a soak. The remaining liquid is either evaporated out of the ventilation system, or passes through and comes out the base as a leachate.

The small amount of leachate can be run to a soakaway pit/leachate drain or captured in a plastic container for disposal elsewhere.

When the user lifts the toilet seat, the air will naturally flow down into the toilet and out of the ventilation pipe, ensuring the user is not exposed to any odours.

WooWoo GT & GT Lux: summary

  • Encourages ideal conditions for ‘good’ bacteria to flourish within the container which will reduce odours and promote composting
  • Simple to use – does not require any special instruction for the user
  • Relatively high capacity – choice of 120-litre or 330-litre composting containers
  • Uses a carbon material promote composting
  • Wind powered or electric fan depending on the nature of the installation
  • Optional porcelain pedestal for ‘at home’ luxury
  • Ideal for semi-public sites
  • Small amount of leachate discharge – can be run into a soakaway, captured or run through the optional GeoTrap unit to remove most of the nitrates and phosphates.

Further links to WooWoo GT products (note that the WooWoo GT can also be purchased with a cabin – known as the WooWoo Loo GT):

WooWoo GT
WooWoo Loo GT Compact Cabin
WooWoo Loo GT Standard Cabin
WooWoo Loo GT Accessible Cabin
WooWoo Loo GT Double Cabin

Alectura composting toilet

Alectura composting toilet with porcelain pedestal

The Alectura batch composting toilet works in a similar way to the WooWoo GT and comes as standard with a porcelain pedestal. Designed for tiny homes, mobile homes and glamping installations (Shepherds Huts, Cabins, Caravans etc). Like the WooWoo GT, it comes with two chambers, one ‘in use’ and one resting/composting.

The porcelain pedestal is a ‘drop through’ design (not urine separator) which makes it simple to use and doesn’t require people to adjust their position. The chamber has a clearance of just 50cm under the floor.

Ventilation of odours and excess moisture is done through a 12v or mains fan which blows through standard 110mm pipework.

The collection chambers each have a capacity of 90-litres (75-litres useable space). Twin blades are turned once a week from a handle on the outside which aerate the contents (promoting aerobic composting) and level off any heaping which may occur in the centre.

Like the WooWoo GT, composting will start to take place within the chamber, and at that point, odours will be naturally reduced. With the carbon-based cover material (wood shavings), forced airflow, aeration and turning, a large amount of the liquid will be consumed as part of the composting process. Any excess moisture will either be evaporated or will pass out of the chamber as a leachate, which can be run into a soakaway pit/leachate trench or captured in a container for later disposal.

When the user lifts the toilet seat, air will be drawn down the toilet pan, into the chamber, and then out of the ventilation system, ensuring no odours escape into the toilet area.

Users can also add ‘effective microorganisms’ which are a specially selected bacteria that will kick start the composting process in the chamber, reducing odours as the bacteria create a natural bio-filter.

Alectura: summary

  • Electric ventilation fan can run from 12v DC or mains AC for complete odour removal and airflow
  • Uses a carbon material promote composting, which in turn, reduces odours
  • Dual mixing arms aerate the contents and promote aerobic composting
  • Simple to use – does not require any special instruction for the user
  • Porcelain toilet pedestal for ‘at home’ luxury and regular appearance
  • Small amount of leachate discharge – can be run into a soakaway or captured

Further links to the Alectura:

Alectura Premium (coming soon)

Kazuba KL1 and KL2

The Kazuba KL1 and KL2 differ in the appearance of the outer building, but the inner ‘workings’ are identical across the range and this part is known as the STK. The STK is sunk into the ground and comprises a high capacity tank with solids collection basket, evaporation plate, durable toilet pedestal and a large chimney with spinning wind vent on the top.

The elements of the Kazuba STK have been designed to enable an airflow that draws air down the toilet pedestal, through the body of the STK and out of the chimney. Using both the heat of the sun on the chimney and the wind vent, the created airflow will enable evaporation of liquids, drying of the solids and removal of all odours.

The large capacity and low maintenance features of the Kazuba waterless toilet, make it ideal for higher traffic sites with no water, sewage or electricity connections where public access toilets are needed.

An added feature of the Kazuba KL1 and KL2 is that there is no discharge to the ground, making it suitable for installation in environmentally sensitive areas where urine or leachate discharge would not be permitted.

WooWoo have over 500 Kazuba waterless toilets installed across the UK. Sites include golf courses, allotments, nature reserves and parks, working in all weathers, winter and summer.

See how they work here on the Kazuba page.

Kazuba: summary

  • Simple to use – does not require any special instruction for the user
  • High capacity
  • Very low maintenance
  • Uses the sun and/or wind to create an airflow which evaporates liquids and removes odours
  • No discharge to the environment
  • Completely off-grid

Further links to the Kazuba:

Kazuba KL1
Kazuba KL2 Compact
Kazuba KL2 Accessible


The Bumper is a new product, developed by Kazuba. It’s transportable so can be relocated if needed to suit the location, time of the year, and changing needs.

As a waterless, chemical-free toilet, it separates the urine from the faeces etc on a conveyor belt, located under the toilet pan (people can therefore use it like any other toilet). Urine flows down and into a holding tank, and ultimately this will need to be pumped out.

Everything else gets moved into the rear chamber at the base of the ‘funnel’ by a solar/battery powered conveyer belt.

All odours are removed in a similar manner to the Kazuba KL1 and KL2 system. The heat of the sun on the chimney/funnel, together with the wind vent, will create an effective flow of air, taking fresh air down the toilet pan, over the lower workings and then up, out and away, ensuring a pleasant visitor experience.

The Bumper has a capacity of around 2,000 visits between empties. Contents are pumped out using pump-out services available all over the country.

Bumper: summary

  • Separates liquids from solids within the base of the toilet
  • Uses the sun and/or wind to create an airflow that effectively removes odours
  • Simple to use – does not require any special instruction for the user
  • High capacity – up to 2,000 visits
  • No discharges to the environment at point of use
  • Completely off-grid and self contained

Further links to the Bumper:

Bumper by Kazuba

Conclusions on odour control in compost toilets

Each compost toilet manufacturer has taken a slightly different route to ensure their toilets work well and are odour-free. The different approaches are matched to the intended user base, capacity or expected requirements of that toilet, but all rely of some form of active ventilation to ensure they deliver an odour-free experience to the user, whilst avoiding the use of water or chemicals.

Odour control can comprise of any or all of the following:

  • separation of liquids and solids, either at point of use or deeper within the toilet
  • use of a cover/mixing material (usually a carbon source), which will create a ‘bio filter’
  • ventilation to assist in evaporation and therefore the reduction or elimination of liquids/moisture
  • ventilation to physically remove odours

Always make sure you follow the recommended maintenance guidelines and that you’ve chosen a solution designed for the type and amount of use you anticipate.

Talk to us here at WooWoo before your purchase and we’ll guide you through the various options to ensure a sweet-smelling toilet success story!

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