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Appropedia:Incubator/composting toilets extra info

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Composting toilets are often built with two buckets for simplicity of construction and operation. Some types of composting toilet have no buckets but only chambers; the compost is generated slowly and continuously as the material progresses through the device. Some require electricity for small heating elements (in cold climates) or fans (to ensure a positive airflow through the system so as to remove smell). Some have the air pipe painted black for natural ventilation (solar heating). Some composting toilets combine the urine and faeces whilst others separate them. The compost formed by the combination of urine and faeces contains more nitrogen and thus requires much greater quantities of carbonaceous residues like sawdust and straw. These toilets are hence more likely to smell if used carelessly. Many of the more complex types require dry access under the toilet via a basement or cellar room.

In some toilets, between the two chambers, there is a trough over which anal cleansing is performed. The anal cleansing water trough and urine funnel is interconnected and flow to a urine tank.

Other composting toilets may have a box with plant leaves that can be used instead. Several types of plants produce leaves that are usable as toilet paper. These include:

  • Brachyglottis repanda
  • Aralia spinosa
  • Oplopanax horridus
  • Arctium minus
  • Abutilon theophrasti
  • Eurybia macrophylla
  • Morus rubra
  • Platanus occidentalis[1]...

Whenever possible, it's best to plant trees that are indigenous to the area in question.

Some composting toilets use vermicomposting. The toilet excrement is then fitted with worms so as to grow food for other animals (ie fish, ...) Worms such as red wigglers, white worms, and earthworms are most often used[2]. See Vermicomposting_toilet


Operation and maintenance[edit]

Before starting to use the latrine, each bucket is half filled with straw, twigs or dry leaves. These provide the necessary additional carbon to the composting process and along with the faeces will compost down to a fraction of their original volume. Occasionally additional straw may be added through the faeces hole if the contents of the chamber start to become wet or slightly odorous. After each use, a spoonful of dry cooking ashes or limecontroversial should be sprinkled down the faeces hole which is then closed using a simple cover.

The two buckets mentioned before are used alternately; after the first one is filled, it is left to decompose (which takes 9 months) and the second is used. Once the second bucket is full, the compost decomposed compost in the first is removed and the chamber is re-primed with straw. The urine tank can be emptied periodically in agricultural fields.

Squatting and defecating is done respectively in the defecation hole and the urine funnel. (A pedestal seat and urine catcher can be arranged if the culture favours sitting rather than squatting.) The anal washing is done over the washing trough (if present). Otherwise, plant leaves can be used for wiping. When this is done, we don't flush but rather simply sprinkle a spoonful of dry cooking ashes, lime, sawdust or leaves[3] into the defecating hole and we close the cover. We wash our hands with soap and water.


In colder climates the composting toilet is best placed within the house as the ambient temperature is higher as well as constant here. This thus allows to eliminate the need of heating (unlike in the outhouse building). The compostation process requires a temperature range between ?°C and ?°C

Construction, maintenance and operational issues[edit]

Many types of composting toilets are available today. They are designed to suit a variety of customs, cultures and climates, and vary enormously in price.

The selection of the most appropriate type and design of composting toilet will depend on many factors, including social and cultural norms, attitude to faeces, existing hygiene and sanitation practices, sources of drinking water, availability of organic residues, climate, soil types, patterns of habitation and local construction materials, and more.

Most, but not all, composting toilets are attached to composting latrines (chambers below the toilet to collect feces). There are some simple systems based on individual toilets, for details see this how-to about making a sawdust toilet where material is collected and composted elsewhere.

Placement[edit]

Any toilet outbuilding would usually be located on the down-wind side of a dwelling, and the same applies for composting toilets. However, when designed, built, and operated properly, the composting toilet does not give any bad odours and can be placed almost anywhere. It should be remembered that vent pipes only function effectively when there is a passage of air over the top of them, so site selection should take account of this. Access for compost removal should be within the owners plot to prevent disputes later, especially important in very crowded communities. A significant advantage of compost toilets is that their location is not dependent on the location of sewers or gradients. They can be established in a confined space either within or beside a human dwelling, whether it is a thatched hut or high rise apartment block.


For a detailed discussion about these issues, see Composting Latrines

  1. Toilet paper plant leaves
  2. http://en.wikipedia.org/wiki/Compost#Vermicompost Worm species used]
  3. Leaves usable as carbon material