Millions of tons of sewage are sent out to sea each year from our islands alone. This is not only a wicked pollution but a terrible waste of valuable nutrients that must then be made up for by the production of artificial fertilisers, made in big factories from fossil resources. Yet it is easy to compost human waste. You need enough space to be able to leave it long enough to rot down properly and you need to add some carbon material to aid decomposition, plus something such as wood ash to keep the acidity down.
It is important that the compost loo building should not be obstructive, and that the site should not be prone to flooding. Where we have chosen to place our one is about 20 metres from the front door, behind the bender greenhouse and set into the hedge. The slope of the bank lent itself to the design.
I started work on the compost loo when builders next door moved in to dismantle an old caravan and were preparing to burn several large sheets of hardboard. Hardboard is excellent stuff to make a form or mould for a concrete construction, so I rescued eight large flexible panels from the bonfire and designed a loo with two compartments.
The air vents, one for each chamber, are bent to stick up beyond the overhang at the back. There are containers for loo roll, sawdust (for increased carbon ration) and wood ash (for alkali and for fly protection).
Before we launched it, I introduced a few brandling worms, placed on the bare earth base, then put a layer or 230mm (9") or so of wood shavings as a basic absorbent layer. We encourage men, and women if so inclined, to pee into a separate urine collector or under a nearby blackcurrant bush.
Total cost of this compost loo was about £25: £10 for nails (I used quite a lot of large ones to ensure the structure stayed up), £10 on cement and ballast, and maybe £5 worth of slabs. Everything else was free.
We estimate that one chamber, being approximately one cubic metre, will take about a year to fill up. We will then place a final layer of green leaves on the contents (to encourage some heat production for a seed and bug-free compost) and seal it for a year while we use its neighbour. Once suitably 'cooked', the compost will be used for fruit trees and bushes.