Compost Toilet

Why Build a Compost Toilet?
Every day in the UK, we use a staggering two billion litres of fresh drinking-quality water - just to flush our loos.

At home, your loo accounts for around 30% of all the water you use. This isn't surprising when a traditional toilet can use 13 litres of water each time.

Composting toilets use little or no water. They treat human waste by composting and dehydration. They don't need expensive sewage systems, cause no environmental damage - and even produce a valuable resource for gardening.

How It Works
A composting toilet is a ventilated container that provides the optimum conditions for decomposition under controlled aerobic (with oxygen) conditions. In the composting process, organic matter is broken down by naturally occurring bacteria and fungi into a dry, non-smelly humus.

The system we have chosen is a Continual Process System; it is in a constant state of composting. Waste enters the system, and composting reduces the volume. It is then harvested after 6-12 months as fully composted material which will be safe to use on the fruit trees on the campsite.

This system works using a urine separating device which means that the poo pile stays dry and does not become anaerobic. When anaerobic (without oxygen) the waste would take much longer to decompose and would become smelly.

Whenever the toilet is used for defecation a small amount of soak material (saw dust or other dry carbon based material) is added to the vault. The purpose of soak is also to prevent the pile from becoming anaerobic by maintaining an open structure and soaking up excess moisture, to adjust the carbon-nitrogen ratio by adding more carbon, and to cover the wastes.

The urine goes safely into a soak-away where it drains away with no smell or damage to the local environment. For an even more sustainable option it is possible to collect and use diluted 'liquid gold' as a nitrogen rich fertiliser in the garden.

The composting chamber is ventilated with a passive ventilation system which further eliminates any unpleasant smells.

Our Design
The structure is 10ft x 6ft and is timber framed using locally soured wood. It is shingle roofed using locally sourced chestnut. The walls are timber-clad, also using wood sourced locally.

The composting chamber is a complete unit that can be lifted into the hole and supports the building.

It is located on the campsite at The Sustainability Centre.