TFS 13-Urine-diverting Dry Toilet (UDDT) – an ecologically beneficial and productive sanitation system

Technology fact sheet

31 Mar 2015

Key Facts

  • An odourless and integrated sanitation method for individual households and other public locations. Works without the need for flushing, hence saving water and protecting groundwater from faecal contamination.
  • Urine and decomposed human faeces (also referred to as ‘humanure’) are used as crop fertilizer and soil conditioner. The safe and productive recycling of nutrients, instead of treating excrement as waste that must disappear, makes UDDT an ecological sanitation system.
  • Offers constant access to a sanitation facility providing improved hygiene and privacy as well as improved security, especially for women and adolescent girls; saves time2, promotes closed local nutrient cycles and reduces fertilizer costs.
  • Links sanitation with agriculture and livelihood.
  • Particularly suited for areas prone to flooding, having high water tables, subject to water shortages, with rocky soils or in fragile ecosystems.

This graph summarizes the results of a sustainability assessment conducted for this technology. The closer the line is to the outer edge of the diagram, the better the technology performs in terms of the particular criterion

Figure 1: UDDT with cemented brick walls (Photo: J. Koknevics)

 

Figure 2: UDDT with a cemented substructure and bamboo walls as superstructure (Photo: J. Koknevics)

 

What is Urine-diverting Dry Toilet (UDDT)?

  • An ecological sanitation (ecosan) approach, using the principle of urine diversion and recycling of decomposed human excreta in local agriculture and horticulture. The technology follows the drop and store practice, with human faeces and urine collected separately using an innovative
    toilet design.
  • A household toilet use in which urine, faeces and anal wash water are separated, stored, and used.
  • On average, a human being discharges about 500 l of urine per year and 100-150 kg of faeces per year equivalent to 50 l of faeces per year (Centre of Excellence in Ecosanitation, 2009; UNICEF, 2011). The average annual excreta from a person contain 4.56 -5.6 kg of Nitrogen, 0.55 – 0.7 kg of Phosphorous and 1.2 – 1.28 kg of Potassium (MPA, 2008; UNICEF, 2011).
  • The toilets are built with a brick/cement substructure with two chambers for excreta collection, a urine outlet and two anal wash water outlets.
  • Faeces are collected in cement chambers and covered immediately with soil, ash, rice hulls, sawdust, or similar material to get them out of sight, control odour and flies, and to absorb moisture. When one excreta chamber is full, it is sealed and the excreta are left to decompose over a period of six months[1] or more, while the second excreta chamber is used. Urine is directly collected in gallon containers (jerrycans) for easy access and use, although it can also be distributed immediately and by gravity via perforated hoses buried in the ground among fruit and other trees.
  • The superstructure (privacy walls) of the toilet can be of low-cost bamboo, wild grass, thatch and mud (see Figure 2) or made with bricks and cement which is more costly (see Figure 1).
  • The technology is designed to withstand floods, with a brick/cement base structure, but can also be used in areas that are not prone to flooding.

 

History

  • Open defecation is a common practice in many areas (rural and urban) of India. The “Total Sanitation Campaign” launched by the government in 1999 had covered 73 per cent of the rural population by 2011. However, sanitation coverage is uneven across the country and in May 2014, only 58 per cent of households below the poverty line (BPL) in Bihar State  owned a latrine.
  • The UDDT as described here has been promoted in Bihar since 2007 by the civil society campaign Megh Pyne Abhiyan (MPA), which translates into Cloud-Water Campaign. An informal network of local organizations and professionals, MPA was registered as a Public Charitable Trust in 2012. MPA was first introduced to Ecosan by Mr S. Vishwanath of Biome Environmental Solutions Pvt. Ltd. during a water workshop titled Jal Manthan Shivir (Water Brainstorming Camp) organized by MPA.
  • Ecosan was promoted in north Bihar using a participatory process of adapting the concept to local conditions and needs, followed by training and support to interested households. A total of 78 households adopted the UDDT and are use it. The project also received technical and financial support from the Stockholm Environment Institute (SEI) and WASH Institute (SEI, 2013).

 

Where it works

  • The UDDT described here is used in Bihar, where about 73 per cent of the total area faces regular monsoon floods.
  • Unsafe sanitation practices spread water-borne diseases during the floods, with increased use of higher land such as .embankments, for open defecation.
  • This UDDT is particularly suited to flood-prone areas due to its solid and, if necessary, elevated construction. However, in areas not affected by floods or waterlogging, lower-cost systems applying the ecosan approach can be used. (UNICEF, 2011; UNESCO, IHP and GTZ,(2006; Canaday, 2011).
  • The technology requires users to be sensitized to the benefits of ecological sanitation and committed to adopt, use and maintain the toilet properly, making safe use of the treated urine and faecal matter.

 

Technological aspects

  • The construction and use of the toilet involves the following steps: 1) choose the location, 2) construct and compact a solid soil elevation, depending on observed flood levels , 3) prepare the substructure with bricks and cement, 4) prepare the squatting pan which covers the substructure, 5) construct the superstructure, 6) use the toilet daily and advise children and visitors in the correct use of the toilet, 7) remove the collected urine before the collection container is full and use as fertilizer for the home garden, 8) use the decomposed faecal matter as fertilizer or soil conditioner.
  • The material needed for the construction of the UDDT is listed in the economic section.

1) Planning: Before starting construction, choose an area i) close to or even attached to the house, ii) close to the kitchen garden, iii) exposed to direct sunlight to enhance decomposition of the excreta and iv) preferably elevated to protect from floods.

2) Flood-proofing: If the site floods, construct a solid and well-compacted soil hill of sufficient height to ensure that the upper edge of the toilet substructure will not be submerged, based on the highest level of flooding in the past. The sides of the hill should be planted with grass or other plants.

 


[1] Or 12 months if no lime or ash is added (according to the WHO (2006) guidelines).

 

Figure 3: Soil is compacted to build a hill on which the UDDT is constructed (Photo: Megh Pyne Abhiyan and Water Action)

Note: Nearby banana plants benefit from regular fertilization by the anal wash water.

 

3) The dimensions of the toilet, in particular the collecting chambers, vary according to 1) the space available for the construction and 2) the size of the household. In deciding the toilet size, future needs should be taken into account as children grow and become adult producers of faecal matter. The toilet design, with the chambers either side by side (see Figure 7) or in a row (see Figures 8 to 14),depends on space availability and household preferences. To choose the appropriate dimension, take into account the amount of faeces and urine produced per person per year. For a household of five persons, the minimum volume should be 750 l . However, for the reasons mentioned below, the recommended volume of the two chambers is 2 546 l (dimension per chamber of 100 x 119 x 107 cm). This is more than three times the volume of the theoretically required minimum volume. The larger size is recommended, based on practical experience in a flood-prone area like north Bihar and takes into account 1) space for guests using the toilet and 2) special requirements for the final height of the toilet surface being above the highest possible flood level and 3) the possibility of the temporary unavailability of one chamber due to repairs. In the latter case, the remaining chamber will have to be used alone.

 

 

The substructure is constructed from bricks and cement, with a cemented lower surface.

Figure 4: Construction of the substructure (Photo: Megh Pyne Abhiyan and Water Action)