Dehydration Vaults

Dehydration vaults are used to collect, store and dry (dehydrate) faeces. Faeces will only dehydrate when the vaults are well ventilated, watertight to prevent external moisture from entering, and when urine and anal cleansing water are diverted away from the vaults.

When faeces are not mixed with urine and other liquids, they dry quickly. In the absence of moisture, organisms cannot grow, pathogens are destroyed and smells minimized.

The use of two alternating vaults in allows the faeces to dehydrate in one vault while the other vault fills. When one vault is full, the Urine-Diverting Dry Toilet (UDDT) is moved to the second vault. While the second vault fills up, the faeces in the first vault dry and decrease in volume. When the second vault is full, the first one is emptied and put back into service.

To prevent flies, minimize odours and encourage drying, a small amount of ash, lime, dry soil or sawdust should be used to cover faeces after each use.

Design Considerations

Dehydration vaults can be constructed indoors or with a separate superstructure. A vent pipe is required to remove humidity from the vaults and control flies and odours. The chambers should be airtight for proper functioning of the ventilation. They should be made of sealed brickwork or concrete to ensure that surface runoff cannot enter.

The WHO recommends a minimum storage time of 6 months if ash or lime are used as cover material (alkaline treatment), otherwise the storage should be for at least 1 year for warm climates (>20 °C average) and for 1.5 to 2 years for colder climates.

In case of alkaline treatment, each vault is sized to accommodate at least 6 months of faeces accumulation. This results in a 6 month storage and dehydration time in the out-of-service vault. The vault dimensions should account for cover material, airflow, the non-even distribution of faeces, and possibly visitors and dry cleansing materials. It can be assumed that one person will require around 50 L of storage volume every 6 months. A minimum chamber height of 60 to 80 cm is recommended for easy emptying and access to the urine pipes.

Appropriateness

Dehydration vaults can be installed in almost every setting, from rural to dense urban areas, because of the small land area required, minimal odours and ease of use. If used in an urban context, this technology relies on a transport service for the dried faeces (and urine) since urban users normally do not have an interest and/or opportunity to use it locally. Dehydration vaults are especially appropriate for water-scarce and rocky areas or where the groundwater table is high. They are also suitable in areas that are frequently flooded because they are built to be watertight.

Health Aspects/Acceptance

Dehydration vaults can be a clean, comfortable, and easy-to-use technology. It is crucial, however, that the users are well trained to understand how the technology works and appreciate its benefits.

When the vaults are kept dry, there should not be any problems with flies or odours. After the recommended storage time, the faeces should be very dry and relatively safe to handle, provided that they did not get wet. However, a low health risk remains. Single dehydration vaults or bins do not allow faeces to sufficiently dehydrate. When the full container needs emptying, the faeces on top are still fresh. Hence, the risk associated with the handling of faecal matter is inherently higher in single vaults compared to double vault designs. The use of alternating chambers is, therefore, recommended. However, research and field tests of sealed faeces containers (or cartridges) for safe transportation and easy cleaning, along with the corresponding logistics, are on-going.

Operation & Maintenance 

Just like the faeces, which are dried, but not degraded in the vaults, dry cleansing materials will not decompose in the chambers. Whenever the material is intended to be applied onto fields without further treatment, it is recommended to separately collect and dispose of the dry cleansing materials. Occasionally, the faeces that have accumulated beneath the toilet should be pushed to the sides of the chamber.

Care should be taken to ensure that no water or urine gets into the dehydration vault. If this happens, extra ash, lime, soil or sawdust can be added to help absorb the liquid. 

To empty the vaults, a shovel, gloves and possibly a facemask (cloth) should be used to avoid contact with the dried faeces.

References

Further Readings

  • Cover image of a reference book or miscellany.

    DEEGENER, S.; SAMWEL, M.; WENDLAND, C. (Editor) (2015): Urine Diverting Dry Toilets. Principles, Operation and Construction. Women in Europe for a Common Future (WECF). URL [Accessed: 29.11.2015]. PDF

    This manual provides the background of ecological sanitation and gives guidance how to construct and operate a UDDT. The manual, originally published in 2006, has been revised based on the experiences of more than 10 years in 12 countries by WECF with local partners.

  • Cover image of a reference book or miscellany.

    ESREY, S. A. (Editor); GOUGH, J. (Editor); RAPAPORT, D. (Editor); SAWYER, R. (Editor); MAYLING, S.H. (Editor); VARGAS, J. (Editor); WINBLAD, U. (Editor) (1998): Ecological Sanitation. Stockholm: Novum Grafiska AB. URL [Accessed: 22.07.2010]. PDF

    This book puts forward ecological sanitation as an alternative to conventional sanitation, and was one of the very first of its kind. It documents different options of ecosan based on dehydrating and composting toilets in use around the world. The book has been reviewed and enlarged since then.

  • Cover image of a reference book or miscellany.

    JOENSSON, H.; RICHERT, A.; VINNERAAS, B.; SALOMON, E. (2004): Guidelines on the Use of Urine and Faeces in Crop Production. Stockholm: EcoSanRes. URL [Accessed: 17.04.2012]. PDF

    These guidelines provide a thorough background on the use of urine (and faeces) for agricultural purposes. Aspects discussed are requirements for plant growth, nutrients in excreta, hygiene aspects, and recommendations for cultivation. It provides detailed guidance on the use of urine for purposes.

  • Cover image of a reference book or miscellany.

    MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010): How to Select Appropriate Technical Solutions for Sanitation. 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 guide is to assist local contracting authorities and their partners in identifying those sanitation technologies best suited to the different contexts that exist within their town. The first part of the guide contains a planning process and a set of criteria to be completed; these assist you in characterizing each area of intervention so that you are then in a position to identify the most appropriate technical solutions. The second part of the guide consists of technical factsheets which give a practical overview of the technical and economic characteristics, the operating principle and the pros and cons of the 29 sanitation technology options most commonly used in sub-Saharan Africa.

  • Cover image of a reference book or miscellany.

    PASHA-MMOLAWA, C. (2006): Health and Safety Aspects of the Use of Products from Urine Diversion Toilets. Pretoria: University of Pretoria. URL [Accessed: 22.07.2010]. PDF

    This research report describes the inactivation of pathogens in human faeces from dehydration toilets under different moisture, temperature and pH conditions.

  • Cover image of a reference book or miscellany.

    RIECK, C. ; MUENCH, E. ; HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. 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.

  • Cover image of a reference book or miscellany.

    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.

  • Cover image of a reference book or miscellany.

    WHO (Editor) (2006): Guidelines for the safe use of wastewater excreta and greywater. Volume IV. Excreta and Greywater Use in Agriculture. Geneva: World Health Organisation. URL [Accessed: 26.02.2010]. PDF

    Volume IV of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater recognizes the reuse potential of wastewater and excreta (including urine) in agriculture and describes the present state of knowledge as regards potential health risks associated with the reuse as well as measures to manage these health risks following a multi-barrier approach.

Case Studies

  • Cover image of a reference book or miscellany.

    DEEGENER, S.; SAMWEL, M.; ANAKHASYAN, E. (2009): UDD Toilets in Rural School Hayanist, Armenia. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 07.07.2010]. PDF

    This case study reports the establishment of a sustainable, affordable and safe school sanitation system in a rural area in Armenia. A total number of 7 Double-Vault UDDTs serve ca. 350 students (females and males) and 26 staff members. Urine is stored for 6 months before application.

  • Cover image of a reference book or miscellany.

    FALL, A. (2009): Urban Urine Diversion Dehydration Toilets and Reuse Ouagadougou Burkina Faso - Draft. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 07.07.2010]. PDF

    This case studies reports form the implementation of ecosan toilets in the peri-urban area of Ouagadougou financed by the European Union. The aim of the project was to demonstrate ecosan on an urban level with a centralised collection and treatment facilities and commercialisation of hygienised urine and faeces.

  • Cover image of a reference book or miscellany.

    KASSA, K. (2010): Urine Diversion Dry Toilet (UDDT) for Agafari´s Household, Arba Minch, Ethiopia. Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 12.12.2012]. PDF

    This case study reports the replacement of pit latrine with UDDT at one household in Arba Minch, Ethiopia. A single-vault UDDT serves family members and rural merchants staying overnight. Urine is applied for banana, mango and lemon plants and the dried excreta are co-composted along with organic material in the owner’s farmland.

  • Cover image of a reference book or miscellany.

    LIPKOW, U. (2009): Urine-Diversion Dehydration Toilets in Rural Areas, Bayawan City, Philippines. Eschborn: Sustainable Sanitation Alliance (SuSanA) . URL [Accessed: 07.07.2010]. PDF

    In Bayawan City (Philippines), UDDTs were installed on household and public level. Vegetable growers and small-scale farmers use the fertilising products.

  • Cover image of a reference book or miscellany.

    WATERAID (Editor) (2008): Assessment of Urine Diverting Ecosan Toilets in Nepal. Kathmandu: WaterAid Nepal. URL [Accessed: 22.07.2010]. PDF

    This study assesses ecosan toilets and their implementation in different areas of Nepal from an n social, technical and financial point of view. It gives recommendations in the view of scaling-up ecosan in Nepal.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2010): Ecological Sanitation in Malawi. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This illustrative presentation on ecological sanitation in Malawi, focuses on the concept of ecological sanitation, types of eco-toilets and basic methods of recycling nutrient from human excreta.

Awareness Material

Training Material

  • Cover image of a reference book or miscellany.

    DEEGENER, S.; SAMWEL, M.; WENDLAND, C. (Editor) (2015): Urine Diverting Dry Toilets. Principles, Operation and Construction. Women in Europe for a Common Future (WECF). URL [Accessed: 29.11.2015]. PDF

    This manual provides the background of ecological sanitation and gives guidance how to construct and operate a UDDT. The manual, originally published in 2006, has been revised based on the experiences of more than 10 years in 12 countries by WECF with local partners.

  • Cover image of a reference book or miscellany.

    ECOSANRES (Editor) (2008): Guidelines on the Safe Use of Urine and Faeces in Crop Production. Factsheet N0. 6. Harare (Zimbabwe): Stockholm Environment Institute EcoSanRes Programme. URL [Accessed: 20.07.2010]. PDF

    This factsheet is a short version of the guidelines for the safe use of urine and faeces for agricultural purposes providing information about requirements for plant growth, nutrients in excreta, hygiene aspects, and recommendations and guidance for cultivation.

  • Cover image of a reference book or miscellany.

    SCHOENNING, C.; STENSTROEM, T.A. (2004): Guidelines on the Safe Use of Urine and Faeces in Ecological Sanitation Systems. Stockholm: Stockholm Environment Institute (SEI). PDF

    These guidelines provide a thorough background on the safe use of urine and faeces for agricultural purposes. Aspects like the health risk associated we the use of human excreta in agriculture and how to limit them are discussed.

  • Cover image of a reference book or miscellany.

    ESF (Editor) (2009): Urine Diversion Dehydration Toilet (UDDT) - Construction Manual. Pune: Ecosan Services Foundation (ESF). URL [Accessed: 07.07.2010]. PDF

    Design and construction manual on that also provides information on the nutrient value of human urine and faecal matter, general hygiene aspects, the reuse of sanitized urine and faecal matter, and costs of various Indian UDDT designs.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. Dehydration Toilet with movable containers . Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Short general and technical description on single-vault UDDTs with movable containers.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. Dehydration toilets Construction Plans – selected examples. Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Description of some examples of construction plans for dehydration toilets.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. Dehydration toilets. Dehydration Toilets without Urine-diversion. Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Short general and technical description on dehydration toilets without urine diversion.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. Double-vault Dehydration Toilets with Urine-diversion . Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Short general and technical description on double-vault UDDTs.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. General Description . Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Short general description on dehydration toilets.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. Single-vault Dehydration Toilets with Urine-diversion . Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Short general and technical description on single-vault UDDTs.

  • Cover image of a reference book or miscellany.

    GTZ (Editor) (2006): Dehydration Toilets. User Instructions for Dehydration Toilets . Eschborn: German Agency for Technical Cooperation (GTZ) GmbH. URL [Accessed: 07.07.2010]. PDF

    Selected examples of graphical user instruction for dehydration toilets.

  • Cover image of a reference book or miscellany.

    RIECK, C. ; MUENCH, E. ; HOFFMANN, H. (2012): Technology Review of Urine-Diverting Dry Toilets (UDDTs). Overview on Design, Management, Maintenance and Costs. 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.

  • Cover image of a reference book or miscellany.

    NWP (Editor) (2006): Smart Sanitation Solutions. Examples of innovative, low-cost technologies for toilets, collection, transportation, treatment and use of sanitation products. Amsterdam: Netherlands Water Partnership (NWP). URL [Accessed: 13.04.2010]. PDF

    Smart Sanitation Solutions presents examples of low-cost household and community-based sanitation solutions that have proven effective and affordable. A wide range of innovative technologies for toilets, collection, transportation, treatment and use of sanitation products that have already helped thousands of poor families to improve their lives is illustrated.

Important Weblinks

  • http://www.susana.org [Accessed: 06.05.2010]

    The official website of the Sustainable Sanitation Alliance SuSanA. SuSanA is a loose network of a number of organizations active in the field of sanitation, founded in 2007. The goals and objectives of SuSanA are to contribute to the achievement of the MDGs, to raise awareness on what sustainable sanitation solutions are and to promote them on a larger scale. The website contains a number of Factsheets by the different SuSanA working groups on various subjects related to sustainable sanitation. There is section where everyone can upload important documents.