How the GL 90 and GT 120  &  330 Systems Work

How the Green Loo GL & GT Systems Work:

Green Loo's GL & GT waterless composting toilets offer a hygienic way to recycle human waste in a manner that avoids polluting and wasting precious water.

Our systems are designed to ensure optimal levels of moisture, temperature, oxygen, carbon and nitrogen required to achieve good composting are present in the chambers. Moisture is managed through a drainage and evaporation system which removes excess liquid from the solids – excess liquid not evaporated is dispersed via a gravel filled dispersal trench.

The GL & GT systems incorporate an unique and ingenious capillary tray at the bottom of the chamber, allowing for drainage when there is excess moisture in the compost and re-hydrating the compost through capillary action (like a self-watering flower pot) when the compost is too dry and requires extra moisture to optimize the composting process. In order for this process to work efficiently, the bottom of the container is filled with 50 mm of peat moss or wood shavings, and the capillary ‘cups’ are also filled.

This unique capillary system is exclusive to Green Loo!


The standard way of installing the  GL & GT systems is as a split system (above is a schematic drawing of the GT 120). The Chute at the top of the container is adjustable from being flush with the container top, to up to 200 - 600 mm above container level, depending on model. This allows for a variety of below floor heights. An additional chute can be added, enabling it to adapt to any below floor space.

Oxygen is regulated using a low-wattage ventilation systems (either solar / battery or mains powered) for the standard electrical options or a ‘Whirlybird’ for our no electricity option. These aerate the compost and also serve to evacuate any odours from the toilet room.

The carbon/nitrogen balance is managed by regularly adding carbon-dense mulch (wood shavings, peat or similar) to the pile. At the end of the composting process microbes have broken down the waste into humus, a soil-like substance with an earthy odour.

A supply of dried flakes of microbes is initially provided with the toilet when it is purchased to facilitate the start of the composting process and can also be used to boost composting during the composting process. Also a spray bottle of Flush Enzymes, which serve to facilitate the composting process, aid with any odours and can be used as a bio - cleaning agent.

When one container has reached capacity, it is removed and set aside to let it continue to compost. An empty container then replaces the removed container. The supplied timber rails aid in the easy exchange of containers, while ensuring accurate placement of the exchange container (see 'underside chute installation' picture below).

Once the fallow container has fully composted, it is emptied and the humus can be buried or used in the garden (depending on local health regulations). The emptied container is then ready for re – use in the system. 

GTCapillary tray - bottom view. Patented and exclusive to Green Loo. 

Capillary Tray Installed - Draws moisture back up into the compost pile when required.

Underseat Chute  Installation - Slides  out of supplied wooden guide & fixing rails at container exchange time.

And forget not that the earth delights to feel your bare feet
and the winds long to play with your hair.

Kahlil Gibran

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