Urine-Diversion Flush Toilet

Compiled by:
Eawag (Swiss Federal Institute of Aquatic Science and Technology), Martin Wafler (seecon international gmbh), Dorothee Spuhler (seecon international gmbh)
Adapted from:
TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014)

Executive Summary

The urine-diverting flush toilet (UDFT) is similar in appearance to a cistern flush toilet except for the diversion in the bowl. The toilet bowl has two sections so that the urine can be separated from the faeces. Both sitting and squatting models exist.

In Out

Freshwater, Urine, Faeces, Dry Cleansing Material, Anal Cleansing Water

Brownwater, Urine, Yellowwater

Introduction

The urine diversion flush toilet is similar in appearance to a cistern flush toilet except for the diversion in the bowl. The toilet bowl has two sections so that the urine can be separated from the faeces.

Urine is collected in a drain in the front of the toilet and faeces are collected in the back. The urine is collected without water, but a small amount of water is used to rinse the urine-collection bowl when the toilet is flushed. The urine flows into a storage tank for further use (use of urine at small or large-scale)or processing (storage, desiccation, struvite production), while the faeces are flushed with water to be treated (onsite pre-treatment and treatment in septic tanks, biogas settlers, anaerobic baffled reactors; semi-decentralised treatment units, e.g. DEWATS systems; centralised sewage treatment plants).

Design Considerations

The system requires dual plumbing, i.e., separate piping for urine and brownwater (faeces, dry cleansing material and flushing water). Transport of brownwater happens via conventional gravity sewer system or vacuum sewer system.

  Schematic of a urine-diverting flush toilet

Schematic of a urine-diverting flush toilet. Source: TILLEY et al. 2014  

The toilet should be installed carefully with an understanding of how and where clogs may occur so that they can be prevented and easily removed. For the discharge of urine, plastic pipes should be used to prevent corrosion. To limit scaling, all connections (pipes) to storage tanks (see urine storage tank) should be kept as short as possible; whenever they exist, pipes should be installed with at least a 1% slope, and sharp angles (90°) should be avoided. A pipe diameter of 50 mm is sufficient for steep slopes and where maintenance is easy. Larger diameter pipes (> 75 mm) should be used elsewhere, especially for minimum slopes, and where access is difficult.

Urine is virtually sterile. It makes up less than 0.5 % of the household wastewater (TETTEY-LOWOR n.y.), but contains most of the essential plant nutrients accounting for about 80 % of the nitrogen (N), 50% of the phosphorous (P) and 60% of the potassium (K) from all nutrients excreted per year per person (JOHANSSON 2000). P and K from urine are generally found as inorganic ions, which are directly plant available. N from urine is transformed into ammonium during storage. Hence, urine has properties similar to commercially available chemical fertilisers.

While the diversion and separate collection of the urine allows reusing all nutrients contained in it, urine diversion flush toilets can also reduce water consumption when compared to conventional 1763-[water-flushed toilets] because people go more often to toilet to urinate only and the urine flush consumes only little water. If urine-soiled toilet paper is collected in a bin, rather than flushed away, water savings could be even greater (MUENCH et al. 2009).

 dubbletten.nu; gustavsberg.com; stman.se; rroevac.de

Different types of urine diversion flush toilets. Source: dubbletten.nu; gustavsberg.com; stman.se; rroevac.de

Odour Control for the Urine Collection System

For the urine pipe, several types of odour seals are used by the toilet manufacturers, such as a valve (Roediger NoMix toilets), a urine/water seal (Gustavsberg toilets) or a novel silicon seal (Dubbletten toilets). Odour locks in the urine diversion toilet’s urine pipe are required to prevent back flow of odour into the toilet room; but these are not necessary in the case of short urine pipe systems of up to 3 to 4 m. For the faeces, odour is controlled by a water seal in a U-bend (just like for conventional cistern flush toilets)(MUENCH et al. 2009).

Health Aspects/Acceptance

Information cards and/or diagrams are essential for ensuring proper use and for promoting acceptance. If users understand why the urine is being separated they will be more willing to use the toilet properly. Proper plumbing will ensure that there are no odours.

Operation & Maintenance

As with any toilet, proper cleaning is important to keep the bowl(s) clean and prevent stains from forming. Because urine is collected separately, calcium- and magnesium-based minerals and salts can precipitate and build up in the fittings and pipes. Washing the bowl with a mild acid (e.g., vinegar) and/or hot water can prevent the build-up of mineral deposits and scaling. Stronger (> 24% acetic) acid or a caustic soda solution (2 parts water to 1 part soda) can be used for removing blockages. However, in some cases manual removal may be required. 

At a Glance

Working Principle

A urine diversion flush toilet is similar in appearance to a cistern flush toilet, except for the diversion in the bowl. The toilet bowl has two sections so that the urine can be separated from the faeces. The urine flows into a storage tank for further use or processing, while the faeces are flushed with water to be treated.

Capacity/Adequacy

As urine diversion flush toilets have been designed for users in high-income countries, they have been manufactured only in ceramic and have a similar appearance to conventional flush toilets.

Performance

Depends strongly on user’s operation and maintenance

Costs

High cost.

Self-help Compatibility

In general, cannot be manufactured locally.

O&M

Washing the bowl with a mild acid and/or hot water can prevent the build-up of mineral deposits; stronger (> 24 % acetic) acid or a caustic soda solution (2 parts water to 1 part soda) can be used for removing blockages however, some manual removal may be required periodically.

Reliability

High, if maintained well.

Main strength

Reuse of urine; can reduce water consumption when compared to conventional water-flushed toilets

Main weakness

Mainly high-cost options available; The toilet should be installed carefully with an understanding of how and where clogs may occur so that they can be easily removed.

Applicability

A UDFT is adequate when there is enough water for flushing, a treatment technology for the brownwater and a use for the collected urine. To improve diversion efficiency, urinals for men are recommended (U.3) (see also urinals).

UDFTs are suitable for public and private applications, although significant training and awareness is required in public settings to ensure proper use and minimize clogging.

Since this technology requires separate pipes for urine and brownwater collection, the plumbing is more complicated than for cistern flush toilets. Particularly, the proper design and installation of the urine pipes is crucial, and requires expertise.

As urine diversion flush toilets have been designed for users in high-income countries, they have been manufactured only in ceramic and have a similar appearance to conventional flush toilets (MUENCH et al. 2009).

 The toilet should be installed carefully with an understanding of how and where clogs may occur so that they can be easily removed.

 

Advantages

  • Reuse of urine as fertiliser
  • Requires less water than a traditional flush toilet
  • No real problems with odours if used correctly
  • Looks like, and can be used almost like, a cistern flush toilet

Disadvantages

  • Limited availability; can not be built or repaired locally
  • High capital and low to moderate operating costs (depending on parts and maintenance)
  • Labour-intensive maintenance
  • Requires training and acceptance to be used correctly
  • Is prone to clogging and misuse
  • Requires a constant source of water
  • Men usually require a separate urinal for optimum collection of urine

References Library

JOHANSSON, M. (2000): Urine Separation - Closing the Nutrient Cycle. Final Report of the R&D Project: Source-Separated Human Urine - A Future Source of Fertilizer for Agriculture in the Stockholm Region. Stockholm: Stockholm Vatten, Stockholmshem & HSB National Federation. URL [Accessed: 06.09.2012]. PDF

KVARNSTROEM, E.; EMILSSON, K.; RICHERT STINTZING A.; JOHANSSON, M.; JOENSSON, H.; PETERSENS, E.; SCHOENNING, C.; CHRISTENSEN, J.; HELLSTROEM, D.; QVARNSTROEM, L.; RIDDERSTOLPE, P.; DRANGERT, J.O. (2006): Urine Diversion - One Step Towards Sustainable Sanitation. (= EcoSanRes Publication Series). Stockholm: Stockholm Environment Institute (SEI). URL [Accessed: 27.07.2010]. PDF

LARSEN, T. A.; LIENERT, J. (2007): Novaquatis final report. NoMix – A new approach to urban water management. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG). URL [Accessed: 10.08.2010]. PDF

MUENCH, E. von; WINKER, M. (2011): Technology Review of Urine Diversion Components. Overview of Urine Diversion Components such as Waterless Urinals, Urine Diversion Toilets, Urine Storage and Reuse Systems. Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 16.10.2013]. PDF

RIECK, C. ; MUENCH, E. ; HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. (= Technology Review). Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 01.07.2013]. PDF

TETTEY-LOWOR, F. (n.y.): Closing the Loop between Sanitation and Agriculture in Accra, Ghana. (= Master Thesis). Wageningen: Wageningen University. URL [Accessed: 27.07.2010]. PDF

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 28.07.2014]. PDF

WINKER, M.; SADOUN, A. (2011): Urine and brownwater separation at the GTZ main office building, Eschborn, Germany. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 01.07.2013]. PDF

Further Readings Library

Reference icon

EAWAG (Editor) (2007): Mix or NoMix - A Closer Look at Urine Source Separation. (= Eawag News, 63). Duebendorf: Swiss Federal Institute of Aquatic Science and Technology (EAWAG). URL [Accessed: 06.02.2012]. PDF

Beside the headarticle about 'Novaquatis', an inter- and transdisciplinary Eawag project, investigated urine source separation and treatment as an option for modern wastewater management, there are more article about urine sepeartion and its development.


Reference icon

GENSCH, R. ; MISO, A.; ITSCHON, G. (2011): Urine as Liquid Fertilizer in Agricultural Production in the Philippines. Cagayan de Oro: Sustainable Sanitation Center Xavier University (XU), the Philippine Sustainable Sanitation Knowledge Node, the Philippine Ecosan Network, and the Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 04.05.2011]. PDF

This field guide has been developed to accommodate the ever-increasing demand for more detailed and scientifically backed information on how to use urine in agricultural production. It is intended primarily for practitioners and experts in the water, sanitation, planning, and agriculture sectors, as well as local and national government officials from the various sectors, NGO and individuals interested and working in the field of agriculture and sustainable sanitation in the Philippines and the wider Southeast Asian region.


Reference icon

KVARNSTROEM, E.; EMILSSON, K.; RICHERT STINTZING A.; JOHANSSON, M.; JOENSSON, H.; PETERSENS, E.; SCHOENNING, C.; CHRISTENSEN, J.; HELLSTROEM, D.; QVARNSTROEM, L.; RIDDERSTOLPE, P.; DRANGERT, J.O. (2006): Urine Diversion - One Step Towards Sustainable Sanitation. (= EcoSanRes Publication Series). Stockholm: Stockholm Environment Institute (SEI). URL [Accessed: 27.07.2010]. PDF

This report of Stockholm environment institute (SEI) presents the current state-of-the-art (2006) of urine-diverting systems, focusing on the Swedish experience and what can be learned from that experience. The intention is to inspire decision- and policy-makers to consider urine diversion for sanitation interventions aimed at meeting the sanitation target of the Millennium Development Goals.


Reference icon

MUENCH, E., v.; WINKER, M.; GIZ (Editor) (2011): Appendix 1 for technology review of urine diversion components. Worldwide listing of suppliers for waterless urinals. (= Technology Review). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 29.04.2011]. PDF

This document contains a worldwide list of suppliers for waterless urinals. The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.


Reference icon

MUENCH, E., v.; WINKER, M.; GIZ (Editor) (2011): Appendix 2 of technology review of urine diversion components. Worldwide listing of suppliers for urine diversion squatting pans (for UDDTs or for urine diversion flush toilets). (= Technology Review). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 29.04.2011]. PDF

This document contains a worldwide list of suppliers for urine diversion squatting pans. The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.


Reference icon

MUENCH, E., v.; WINKER, M.; GIZ (Editor) (2011): Appendix 3 of technology review of urine diversion components. Worldwide listing of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets). (= Technology Review). Eschborn: Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH. URL [Accessed: 29.04.2011]. PDF

This document contains a worldwide list of suppliers for urine diversion pedestals/seats (for UDDTs or for UD flush toilets). The tables of suppliers provided here are not complete listings but give only an indication of available products. If you spot errors or omissions, please contact the authors at ecosan@giz.de. In the brackets below each listing the date for provision of the information/last update of information is given. Please be aware that not all information is from 2011. An entry in this list does not imply a recommendation by GIZ. Costs are indicative only.


Reference icon

MORGAN, P.; SHANGWA, A. (2009): How to Make Simple Pedestals. The Chisungu Primary School Water and Sanitation project. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

This presentation offers the chance to learn about how to make different kinds of pedestals.


Reference icon

RIECK, C. ; MUENCH, E. ; HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. (= Technology Review). Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 01.07.2013]. PDF

This publication offers a complete overview of UDDT functions, design considerations, common operation and maintenance issues and generalised installation costs. Its focus is on applications in developing countries and countries in transition, although UDDTs are also applicable in developed countries.


Reference icon

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). URL [Accessed: 28.07.2014]. PDF

This compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.


Reference icon

TOUBKISS, J. (2010): How to Manage Public Toilets and Showers. (= Six Methodological Guides for a Water and Sanitation Services' Development Strategy, 5). Cotonou and Paris: Partenariat pour le Développement Municipal (PDM) and Programme Solidarité Eau (pS-Eau). URL [Accessed: 19.10.2011]. PDF

The purpose of this decision-making aid is to provide practical advice and recommendations for managing toilet blocks situated in public places. It is primarily aimed at local decision-makers in developing countries and at their partners (project planners and managers).

See document in FRENCH


Reference icon

UHLMANN, C.; GOOSE, P.; OSER, M. (2013): Maintenance Guide for Roediger NoMix Toilets. Duebendorf: Eawag. URL [Accessed: 26.09.2013]. PDF

This maintenance guide for Roediger NoMix Toilets proposes a maintenance strategy based on the experiences at Eawag. It gives an introduction to NoMix toilets, maintenance instructions and problem solving.


Case Studies Library

Reference icon

GERMER, J. (2009): Urine-diverting vacuum sanitation system, Beijing. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA) . URL [Accessed: 07.07.2010]. PDF

Urine diversion vacuum flush toilets were installed in an urban building. Urine collected in the source-separation sitting/squatting toilets as well as the waterless urinals is drained by gravity. Faeces are withdrawn by vacuum suction. There is currently no reuse of urine and brownwater, but they flow to the sewer.


Reference icon

GERMER, J.; KANGNING, X. (2009): Source separating sanitation in Olympic Forest Park, Beijing. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 07.07.2010]. PDF

Urine diversion low-flush toilets where installed in public toilet blocks of the Olympic park. Urine was collected for reuse and brownwater was treated in a septic tank and moving bed reactor before being transformed into compost. The aim of the system was to interlink the sanitation material flows as a water and nutrient source with the green areas of the park as a water and nutrient sink. Reduced water and energy demand as well as the substitution of fertilizer by urine and faeces-derived manure were expected advantages.


Reference icon

GOOSSE, P. (2009): NoMix-Toilettensysteme. Erste Monitorergebnisse vom Forum Chriesbach. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG) . URL [Accessed: 10.08.2010]. PDF

The NoMix toilet systems of Eawag’s main building have been in operation for three years. So far, NoMix toilets, waterless urinals and urine pipes do not show any clogging problems and no odour problems occurred inside the building. However, outside the building, odour problems occurred because of ammonia gas emissions from the urine pipes. For the moment, the most important remaining problem for an efficient separation of urine and faeces is the correct use of the NoMix toilets by non-acquainted users.


Reference icon

LARSEN, T. A.; LIENERT, J. (2007): Novaquatis final report. NoMix – A new approach to urban water management. Duebendorf: Swiss Federal Institute for Environmental Science (EAWAG). URL [Accessed: 10.08.2010]. PDF

From 2000 to 2006, the cross-cutting project Novaquatis explored the potential of urine source separation – also known as NoMix technology. Novaquatis comprises nine work packages, largely organized around the various stages of a nutrient cycle (e.g. user acceptation, sanitary technologies, storage and transport, urine treatment and fertiliser production, micropollutants in urine, urine-based fertilisers). The final report contains the results of all working packages as well as a practical guide for interested NoMix user.


Reference icon

OLDENBURG, M.; WERNER, C.; SCHLICK, J.; KLINGEL, F. (2009): Urban Urine Diversion and Greywater Treatment System Linz, Austria. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 24.09.2013]. PDF

This case study discusses a medium-scale pilot project in a new urban area in Linz, Austria. General objectives were the creation of a sustainable settlement in a new city district (high demand for residential buildings) and the establishment of ecological buildings and low energy construction concepts. Among specific objectives was the implementation of innovative solutions for water supply and wastewater treatment with a reduction of the infrastructure costs for municipal wastewater treatment. Also, the aim was to establish a holistic sanitation approach enabling the use of nutrients contained in excreta or wastewater in agriculture and to research treatment of micropollutants in urine.


Reference icon

WINKER, M.; SADOUN, A. (2011): Urine and brownwater separation at the GTZ main office building, Eschborn, Germany. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 01.07.2013]. PDF

This case study is about a demonstration project in the headquarters of GTZ in Eschborn, Germany. The project consists of 50 urine-diversion flush toilets, 23 waterless urinals and 10 m³ urine storage tank.


Awareness Raising Material Library

Reference icon

GEORGE, R. (2009): Yellow is the new Green. In: The New Your Times, 27. URL [Accessed: 27.07.2010]. PDF

This opinion contribution from Rose George published in the New York Times emphasises the enormous potential urine as a sustainable fertiliser source.


Reference icon

GRUNBAUM, M. (2010): Gee Whiz: Human urine is shown to be an effective agricultural fertilizer. In: Scientific American 30. URL [Accessed: 17.04.2012]. PDF

The Scientific American is a popular science magazine in the US. This article, written for laymen, states that urine not only promotes plant growth as well as industrial mineral fertilizers, but also saves energy.


Training Material Library

Reference icon

RUED, S.; WERNER, C. (2007): Ecological sanitation within GTZs main building in Eschborn - A demonstration and research project. In: Proceedings of the International Conference on Sustainable Sanitation: Eco-Cities and Villages, 26-31 August 2007, Dongsheng/Erdos. URL [Accessed: 10.08.2010]. PDF

PDF-presentation on urine diversion flush toilet systems at the GTZ headquarter.


Reference icon

WECF (Editor) (2010): How to Separate Urine. Utrecht/Munich/Annemasse: Women in Europe for a Common Future. URL [Accessed: 06.01.2011]. PDF

This flyer contains information about the importance of urine reuse. The nutrients in urine are easily taken up by plants. The fertilised plant will grow faster, develop more leaves and produce higher yields. Applying urine to crops instead of chemical fertilisers saves money and energy and produces a similar yield. One person produces about 500 liter urine per year.


Important Weblinks

http://www.berger-biotechnik.com/ [Accessed: 18.08.2010]

German provider of pre-fabricated composting toilets.

http://www.dubbletten.nu [Accessed: 10.08.2010]

Homepage of a Swedish urine diversion flush toilet supplier (only in Swedish).

http://www.eawag.ch/forschung/sww/gruppen/rttc/ [Accessed: 17.10.2013]

Introducing the Reinvent the Toilet Challenge project at Eawag in cooperation with EOOS and Makerere University in Uganda, funded by the Bill & Melinda Gates Foundation.

http://www.ecovita.net/ [Accessed: 10.08.2010]

Ecovita is a U.S.-based ecological toilet supplier (waterless, urine separation flush toilets, urine diversion composting toilets, etc.).

http://www.flickr.com/photos/gtzecosan/sets/72157626481209996/ [Accessed: 17.10.2013]

SuSanA Flickr picture collection on UDFT.

http://www.novaquatis.eawag.ch/ [Accessed: 10.08.2010]

Novaquatis – a cross-cutting Eawag research project was concerned with urine source separation as a new element in wastewater management.

http://www.saniresch.de/ [Accessed: 10.08.2010]

This is the main homepage of the SANIRESCH project (SANItaryRecycling ESCHborn) which focuses on the treatment and recycling of the urine, brown- and greywater collected at the headquarters of the German Technical Cooperation (GTZ) GmbH in Eschborn, Germany.

http://www.separett.com/ [Accessed: 10.08.2010]

International supplier of urine diversion composting toilets.

http://wostman.se/ [Accessed: 10.08.2010]

Homepage of a Swedish urine diversion flush toilet supplier.

http://abettertoilet.org/ [Accessed: 23.11.2013]

The sanitation technology paradigm is under review, as past approaches are not sufficient or affordable to close the sanitation coverage gap. In 2011, the Bill & Melinda Gates Foundation (BMGF) launched the bold Reinvent the Toilet Challenge (RTTC) program to promote the development of radically new innovations to address the sanitation challenge on a large-scale. The RTTC is premised on the fact that ground-breaking improvements are required in toilet design and fecal sludge management to close the urban sanitation gap. The RTTC is focused on reinventing the flush toilet, a break-through public health invention that has not changed substantially since the first flush toilet patent was issued in 1775.