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Urine Diverting Dry Toilets

In a Urine Diverting Dry Toilet (UDDT), no water is used for flushing. The principle of a UDDT is to keep faeces and urine separated.

For this purpose special seats or slabs are needed, which safeguard the separation. Such slabs are industrially produced (e.g. in China, Georgia and Kazakhstan) but can also be constructed locally. After the separation the faeces are covered with an adsorbing organic material and kept directly in a special faeces chamber or in a container placed in the faeces chamber of the toilet.

The urine is stored in a tank. The volume of urine tanks for households usually ranges from 510 liter canisters to 1-2 m3 tanks. Generally 10 to 20 L canisters are common, as it allows the urine to be carried and applied easily on the fields. Larger tanks make longer storage periods possible, which can be helpful especially in winter, when application is more difficult and the fertilizing effect is less than in spring.

The seat of an industrially produced UDDT

Due to the separation, urine can be used easily and safely as fertilizer on a household level without extra sanitizing. If urine is used as fertilizer for commercial farming, higher infection risks are involved and therefore urine has to be stored at least for six months. In colder climates a longer storage time can be suggested. In this case two tanks can be used; the volume of one tank should be enough to collect urine for more than 6 months. Before faeces can safely be used, it have to be sanitized, i.e. pathogens have to be eliminated. This is achieved by different methods, such as alkaline treatment with ashes, adding soil and sawdust, and storing. During storing time, a dehydration and/or composting process takes place. The whole storage and/or composting time depends mainly on the temperature. The WHO Guidelines recommend 2 years for temperate climates (2-20C).

More information:

  • WECF made a five minute film about the operation and benefits of ecosan or urine diverting dry toilets (UDDT) in areas without reliable water supply. Watch No flush, No Waste here.
  • WECF and Natracare made a two minute film about the positive impacts of ecosan toilets for school girls in Tajikistan.