Compost loo retrofit

This design helped us close the fertility loop by returning the nutrients removed from the garden as food to the soil as humanure compost. The loo design was inspired by Jo Jenkins' Humanure Handbook, but the composting side was entrusted to commercial Hotbin composters which cope well with the task with a few tweaks. Waste from the garden is used as cover material for the loo, to add carbon and stop the smells. Finished humanure compost is indistinguishable from the more usual kind, and gets used for mulching crops which are not eaten raw.

The design required a few tweaks in other designs too, like rearranging the planting around the expanded compost area in the garden. The project showed that humanure composting is feasible in a small garden, and it is possible to retrofit compost loos almost anywhere. And while such retrofitted solutions may not be the lowest-maintenance option (unlike integrated composting toilets designed at the building stage, or vermicomposting flush toilets), it gives us an opportunity to witness at close quarters the alchemy of waste becoming a valuable resource.