An UDDT seems to be the most environmentally friendly alternative, but for some contexts, a composting toilet might seem preferable (like rentals, or camping sites where people don't always remember to use the toilets correctly).

What are the disadvantages of using a composting toilet in terms of:

  • Waste generation: does the composting chamber generates black water? gases?
  • Odour: does the presence of moisture and greater humidity contribute to the generation of unpleasant odours?
  • Maintainability: how often do you have to take care of the compost?

For what I have gathered, a double chamber UDDT needs to be maintained once a year, does not generates waste and, since it's dry, it doesn't smell bad. Can all these characteristics be achieved by some composting toilet design?


Check this out: http://www.strawbalecentral.com/cinva/sunnyjohn.html

This is a 'mouldering toilet' It composts, but slowly.


Bulky: You need room to move a drum in and out under the seat.

Needs to be kept warm to work. (True of most non sewage toilets)

Upsides: Simple, stink free.


While composting toilets are a big issue in terms of size, cost or practicality. Never the less; urine is instantly recyclable and needs no seperate handling. Urine is a great natural fertilizer on it's own (from a healthy individual). It is largely composed of 95% water and it's main dissolved ingredients are Nitrogen, Phosphorus and Potassium. With an average NPK ratio of 18:2:5. Dilute it in water every 10 to 1 and apply directly to any plant.

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