In July we built a new structure, this time to house our humanure. It’s a twin chamber system, constructed mostly of pallet wood. One chamber composts while the other is being filled. When the material in the first chamber is fully broken down, we will take out the compost and put it around the fruit trees in our new forest gardens.

A mixture of straw, green matter, earth and ash is added to each human deposit to balance the carbon/nitrogen ratio, introduce useful bacteria and keep smells down. Users have the option to squat or use a wooden toilet seat box.

There is a straw urinal/swale directly below the toilet to catch any possible run off in the wet months and to discourage people from peeing in the toilet (this slows down the composting process).

Willow will be planted below and around the structure to make use of any nutrients that excape from the compost chambers. The willow will be coppiced and provide withies for basket making etc. as well as visual screening for the structure itself.

The chambers are ventilated by passive solar convection chimneys made from black drainpipes. These heat up in sunlight and create convection currents that help to extract fumes from the chambers. The vents are fitted with mesh screen to reduce fly problems.

Compost toilets and tree bogs are an excellent way of making use of a resource that is unfortunately more usually added to large quantities of chemically purified mains water, turned into a pollutant, and then expensively treated in sewage works or sometimes pumped out into the sea.

See also: Building a tree bog