Urine diversion

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Not to be confused with Urinary diversion.
UDDT in South Africa
UDDT in Burkina Faso

Urine diversion refers to the separation of human urine from feces at the point source, i.e. at the toilet fixture or outhouse. Separation of urine from feces allows human waste to be treated separately and used as a potential resource. Applications are typically found where connection to a sewer based sanitation system is not available or areas where water supplies are limited.

A toilet used to facilitate the separation of human waste products is called a urine diversion toilet or UDT. The bowl usually has two separate receptacles which may or may not be flushed with water. If flushed, the toilet is usually referred to as a UD toilet or UDT. If not flushed, it is a urine diversion dry toilet or UDDT. Separated feces may be composted or dried. If dried, the overall system is called a urine diversion dehydration or desiccation toilet or UDDT.

Most forms of ecological sanitation are based upon urine diversion.


Separate treatment of the two types of waste is justified since urine is nearly sterile and low in pathogens, provided an individual is healthy.[1] This means that urine can be readily utilized as a fertilizer or discharged with less risk to community.[2]

Human feces, on the other hand are high in pathogens, including up to 120 viruses and should either be composted or dried and burned as a biofuel.[3] When feces are used without composting for several months, it is called night soil, which is recognizably odiferous. Its use in some areas has been so ingrained that entire cultures will not eat any vegetables or fruits unless they are thoroughly cooked.[4]

Ash and/or sawdust are usually added to speed the composting process. Of the two, ash decreases microbial activity faster.[5] Dehydration and conversion into a biofuel is typically accomplished by exposure to dry air and/or solar heat.

Some toilets integrate composting or desiccation as part of an entire system as in an installation in Khuvsgul National Park in Mongolia.[6]

Other toilets focus on removal of urine so feces can be composted at a different location as in the "floating toilet".[7][8]

Whether the feces are handled on site or hauled to another location, the weight and volume of material is reduced by separating out urine. Additionally, treatment is simplified and faster.[9] Some web sources suggest that keeping urine within the overall compost is beneficial by adding nitrogen; however, urine is mainly water and this increases moisture content of the compost increasing composting time.[10][11] Urine diversion is the main reason one manufacturer of composting toilets claims their product is less problematic than toilets that do not feature diversion.[12]

UD toilets (UDT) and UDD toilets (UDDT)[edit]

There are several commercially available UD and UDD toilets. Many look like a conventional sit down or squat toilet and the bowl is divided into two sections. The front section collects urine and the rear section feces. One UDDT manufacturer calls their product a "UD Dry Toilet".[13] More elaborate versions feature separate flushing with water in each compartment. More basic versions essentially consist of an outhouse with a divider and one or two containers below. One container is typically used in floating toilets and urine is immediately discharged to local waters.

NatSol, a UK company that specialises in urine diverting dry toilets, has developed a solution that avoids the usual problems of blockage and fouling of urine separating bowls. It uses the Coandă effect to divert and send urine to a soakaway, rather than rely on evaporation.[14]

Owing to limited water supplies in outer space, NASA started in May 2009 to utilize a UDD toilet to recycle urine into drinking water.[15]


  • A prime driver of this type of approach to sanitation is an organization called Women in Europe for a Common Future (WECF). The WECF and local partners have built more than 20 urine diverting dry toilet buildings for schools as demonstration projects in the Eastern Europe, Caucasus and Central Asia (EECCA) region.[16]
  • Georgia (country) - The first indoor UDD toilet opened in a school for socially vulnerable children by WECF partner RCDA. The construction was financially supported by the Dutch Ministry of Foreign Affairs and UNICEF.[17]
  • Mindanao, Philippines - The first urine-diversion dehydration toilet of Mindanao was inaugurated in November 2005.[18]
  • Haiti - SOIL has built urine-diversion toilets and composting waste treatment plants in Port-au-Prince as part of the 2010 Haiti earthquake emergency relief effort and in northern Haiti. There are currently 20,000 people using these units and more than 400,000 liters of compost have been produced as a result.[19]
  • Cambodia - Lien Aid has assisted with the development and implementation of floating toilets that utilize UDD in a project called “River of life”[20]
  • Rwanda - UDDT at a public toilet and a school near Kigali[21]
  • China - in 2003 reportedly had 685,000 operating UDD toilets spread out among 17 provinces[22]
  • Boating - Chris Melo, sailboat resident and nautical engineer, cites 9 reasons to convert from conventional nautical toilets that store waste in black water tanks, or immediate discharge it overboard, to a UDD composting toilet[23] Two competing manufactures for nautical use call their products Nature's Head and the Air Head Toilet.[24]
  • Camping - Leave no trace is not only a philosophy but a necessity in areas where human waste left behind would not decay naturally. There are now portable UDD toilets that allow feces to be collected and packed out. Only near-pathogen-free urine is left behind.[25]

See also[edit]

External links[edit]


  1. ^ http://weblife.org/humanure/chapter7_2.html Web article on pathogens that in turn mainly came from book, Appropriate Technology for Water Supply and Sanitation, by Feachem et al., World Bank, 1980.
  2. ^ http://www.ncbi.nlm.nih.gov/pubmed/18578152 Evaluation of human urine as a source of nutrients for selected vegetables and maize under tunnel house conditions in the Eastern Cape, South Africa, Lead author: Mnkeni PN, April 2008
  3. ^ http://ecosanservices.org/pdf/UDD-ToiletsTraining%20material.pdf UDD-Toilets and urine management
  4. ^ http://weblife.org/humanure/chapter7_2.html Web article on pathogens that in turn mainly came from book, Appropriate Technology for Water Supply and Sanitation, by Feachem et al., World Bank, 1980.
  5. ^ http://www.ncbi.nlm.nih.gov/pubmed/19303763 Comparing microbial die-off in separately collected faeces with ash and sawdust additives, Author Niwagaba C et al, 2009
  6. ^ http://www.khovsgolinn.com/Khuvsgul%20Inn%20Ecosan%20Pilot.pdf Khuvsgul Inn, Ecosan pilot-project, Khatgal Mongolia
  7. ^ http://washtech.wordpress.com/tag/urine-diverting-toilets/ Floating toilets for floating villages on Cambodia’s Tonle Sap lake
  8. ^ http://www.adb.org/Water/Photos/CAM/floating-toilets/Default.asp Sample Designs: Floating UDD Toilets, Asian Development Bank Website
  9. ^ http://www.cdc.gov/haiticholera/sanitation.htm CDC Document Potential sanitation solutions for emergency response, February, 2011
  10. ^ http://www.sswm.info/category/implementation-tools/water-use/hardware/toilet-systems/composting-toilets Composting toilets, by Dorothee Spuhler
  11. ^ http://mooseville.weebly.com/7/post/2011/07/composting-is-easy.html Composting is easy, by Daisy Gerber, July 2011
  12. ^ http://ecovita.net/news/ How to fix a leaking (other brand) composting toilet, by July 2009
  13. ^ http://www.eqc.kyoto-u.ac.jp/ud-toilet/top_en.html UD Dry Toilets
  14. ^ COMPUS Full Access dry toilet
  15. ^ http://www.nasa.gov/home/hqnews/2009/may/HQ_09-096_Recycled_Water_Go.html NASA Gives Space Station Crew 'Go' to Drink Recycled Water, May 2009
  16. ^ http://sanitationupdates.wordpress.com/tag/urine-diverting-toilets/ Sustainable and safe school sanitation brochure, 2009
  17. ^ http://www.wecf.eu/english/articles/2010/06/rcda-schooltoilet.php First Indoor UDD Toilet Georgia opened in school for socially vulnerable children by WECF partner RCDA
  18. ^ http://puvep.xu.edu.ph/snews/ecological_sanitation/uddt_mindanao/ UDDT Update Mindanao: 60 Units Already Completed
  19. ^ Christine Dell'Amore, "Human Waste to Revive Haitian Farmland?", The National Geographic, October 26, 2011
  20. ^ http://washasia.wordpress.com/category/regions/east-asia/cambodia/ UDD and floating toilets in Cambodia
  21. ^ Rwanda - UDDT at a public toilet and a school near Kigali http://www.flickriver.com/photos/gtzecosan/sets/72157627175799611/
  22. ^ http://www.iwc-berlin.de/medienpool/iwc_m77_61000000012/iwc_20071011140736_1_840856.pdf Water and Sanitation related Activities, German Gesellschaft für Technische Zusammenarbeit(GTZ)
  23. ^ http://ecovita.net/news/wp-content/uploads/2009/07/NaturesheadOnBoat2.pdf
  24. ^ http://forum.woodenboat.com/showthread.php?114077-Nature-s-Head-vs.-Air-Head-Toilet Wooden Boat Forum
  25. ^ http://www.flickr.com/photos/gtzecosan/2921708370/ Photo of Foldable camping UDD toilet by Separett (Sweden)