500 Year Vision

Take pleasure from walking lightly on this Earth

Learning to love composting toilets

August2

One strong motivation for moving to South Bohemia was the spirit of enviro-entrepreneurship*.  Back home I had been working on a design for an accessible bathroom – to meet the needs of carers and those with profound disabilities, and organisations which want to be able to cater for them.  The design was to be based on a shipping container and fully independent – so not needing mains water and sewage – by harvesting rainwater and composting waste.  It could go anywhere on a temporary or permanent basis.  I had done a lot of research, and wanted to experiment with the various component parts of the system. Luckily…

When we first arrived at Nový Mlýn, we were surprised to discover that our 130 year old house did not have a water treatment system or water supply… unlike our fully serviced neighbour who had built his new home downhill of the house.

Life was hard for the eighteen months it took us to get permission to pump water from a new well to the house, but it gave us ample opportunity to radically reduce the amount of water we use, and many of these good habits have stuck.

Mike immediately constructed a toilet – an inglorious outhouse that at first didn’t even have a door.  We were clear that we wanted to actually use the compost which was generated, so we would dig a new poo hole and move the structure onto it every few months.  This was not a one person job, and gave us the inspiration for the Teepoo (more later).

The use of drinking water for toilet flushing is extremely inefficient because then contaminants then need to be removed from the water.  Urine is a sterile, ph neutral  fluid which contains nitrogen, phosphates and potassium – the main macronutrients required by plants. It therefore makes sense to operate waste separation at source – something people soon get used to.

There is a university in Austria working on a urine only toilet – and it would be nice to have a bespoke design (a wiidet) , however, instead we installed ‘rock bogs’ inside the house, by filling the water in the bottom of the toilets with pebbles. This greatly reduced the amount of water needed for flushing (a single litre for a completely clean flush), and provided people with a very visual reminder not to use the toilet for anything other than liquid.  We then installed our WWUK reed bed – a plant based system of cleaning waste water, and connected the bathroom plumbing to that.

Any household with more than one toilet could instigate a rock bog (urine only toilet) and therefore massively reduce the amount of water needed for flushing. It’s really, really simple. It would be nice to have a toilet insert designed to take the place of the stones, but stones are simple,  freely available and aesthetically pleasing.

As well as rock bogs inside the house, we now have a more sophisticated composting toilet system attached to the house.  Composting toilets will smell bad if they get wet for any reason (urine or rain water) or if waste is not adequately covered.  We purchased an insert to catch urine – as well as the box and a supply of cornstarch biodegradable bags. We think this beats even Moule’s Earth Closet – though an earth ‘flush’ would be great.

We have hosted 75 volunteers over the last two years. They have all but one been able to operate the composting toilet without leaving any unpleasant surprises.  We would recommend leaving a vinegar spray in the cubicle to clean the plastic as you would need to with any other toilet.

While the job of emptying the soil box is not pleasant, waste is always dry and covered with a cup of ash or earth, you tie the bag shut and put the lid on the box before moving the box to a ready prepared hole. You tip in the bag, then cover it with earth by digging the next hole.  We don’t bury compost directly in the vegetable garden, but instead under the paths through it. This trench system means that we are efficiently closing the loop and returning nutrients to the earth.

*My very first unsuccessful business was the Vermenathon Forest project which I worked on obsessively during the last few years of the millennium. This was, in short, a tree sponsorship scheme which people could visit physically and virtually – I’m happy that more successful business people had the same idea.

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