… by Andrew Rettig

Designed for medium maintenance, tight spots and above ground, this compost toilet uses the latest in low-budget compost toilet technology (ie worms and aeration!) to breakdown humanure within 3 months (1 year rest time is reccommended for complete pathogen destruction). Using a false floor, PVC Pipe and a Compost Screw (not pictured), this system could be made for under $150 (depending on what matertials you have lying around the house).

The compost toilet has been designed for low cost installation above ground using minimal infrastructural requirements.

  • Material cost can be as low as $50 depending on what extra bits and tools you have lying around (for one barrel).
  • Barrel to people ratio is about 2 barrels for 2-3 people when used everyday.
  • Best to have a “two barrel rotation system”. When you fill up one, leave for 6 months and start using the other.
  • The toilet is designed for squatting so be careful not to fall in!
  • When it is time for you to close the link in the nutrient cycle (i.e. use the compost toilet) think about privacy as these types of systems are currently illegal without council approval.
  • Try to keep urine separate from the compost toilet (CT) as too much moisture causes the breakdown process to turn anaerobic.  The CT operates aerobically so it requires some moisture occasionally – eventually you sense what the CT is doing and can adjust your behaviour accordingly.
  • Trying to get as much airflow as possible through the mass of rich humanure is the aim.  Some people will install a small extraction fan to the upper ventilation outlet pipe or extend the pipe and paint it black for natural thermal convection (i.e. black pipe attracts sun and heats up top layers of air causing a convectional current of air sucking through the lower ventilation holes.
  • Put in a small bucket full of compost worms, to help the break down process.
  • Complete the Carbon : Nitrogen ratio by adding carbon matter.  Sawdust can tend to clog up and form ‘cakes’ that don’t break down very well.  So wood shavings from your local saw miller can be used (be wary of treated timber and particle board saw millers).  Wood shavings have greater airspaces than saw dust – see the theme of maximum air flow through your system?
  • As for the Urine that can’t go in the CT – Urinate in a bucket and fill with water at a ratio of about 1:20 i.e. a twenty litre bucket for a litre of urine.  You can use this on your fruit, native trees or any other above ground crop as a little Nitrogen hit and also for watering purposes.
  • Once you have filled a barrel, leave the full pickle barrel for about 6 months (to be safe) before removing the contents for burial under fruit trees or incorporation into the soil for a green manure crop.  It is best to leave it as long as possible, to let all the good microbes and worms break down any potential harmful microbes into good.

For the book that could change your life read:

The Humanure Handbook by Joe Jenkins published by Jenkins Publishing http://www.jenkinspublishing.com/. This book outlines a huge variety of different methods people have tried in the past and also brings our attention to our current general mind state of ‘faeceophobia’.  He also deals with all the questions raised about bugs and pathogens extremely well.

Share This

Share this post with your friends!