Pour-flush Toilets

Compiled by:
Eawag, Martin Wafler (seecon international gmbh), Dorothee Spuhler (seecon international gmbh)
Adapted from:
TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2013)

Executive Summary

A pour flush toilet is like a regular cistern flush toilet except that the water is poured in by the user, instead of coming from the cistern above. When the water supply is not continuous, any cistern flush toilet can become a pour flush toilet.

In Out

Faeces, Excreta

Brownwater, Blackwater, Faecal Sludge

Introduction

Just like a cistern flush toilet, the pour flush toilet has a water seal that prevents odours and flies from coming back up the pipe. Water is poured into the bowl to flush the toilet of excreta; approximately 2 to 3 L is usually sufficient. The quantity of water and the force of the water (pouring from a height often helps) must be sufficient to move the excreta up and over the curved water seal.

Both pedestals and squatting pans can be used in the pour flush mode. Due to demand, local manufacturers have become increasingly efficient at mass-producing affordable pour flush toilets and pans. 

Design Considerations

The water seal at the bottom of the pour flush toilet or pan should have a slope of at least 25°. Water seals should be made out of plastic or ceramic to prevent clogs and to make cleaning easier (concrete may clog more easily if it is rough or textured). The S-shape of the water seal determines how much water is needed for flushing. The optimal depth of the water seal head is approximately 2 cm to minimize the water required to flush the excreta. The trap should be approximately 7 cm in diameter. Pour-flush pans can be connected to twin-pit for pour-flush latrines, a pre-treatment and treatment units such as septic tanks, biogas settlers, anaerobic baffled reactors, toilet-linked biogas plants etc. or a small-bore or solids-free sewer or conventional sewer system.The collection system on its turn has to be connected to a appropriate treatment system (see also wastewater treatment).

Superstructure

 WAFLER (2009)

Perspective sketch of Malaprabha Biogas Plant with attached pour-flush toilets. Source: WAFLER (2009)

The superstructure’s primary function is to provide privacy and protection to the user from the natural elements. The costs for the superstructure vary depending upon the kind and type of construction technique and material used (e.g. bamboo, mud, bricks, cement blocks, woven palm fronds, etc.). Construction of a temporary superstructure, which can be replaced afterwards with a permanent one, may be considered.

Health Aspects/Acceptance

The pour flush toilet (or squatting pan) prevents users from seeing or smelling the excreta of previous users. Thus, it is generally well accepted. Provided that the water seal is working well, there should be almost no odours and the toilet should be clean and comfortable to use. Pour-flush toilet pans are most commonly used in combination with a single- or twin pit pour flush latrine and therefore installed outside the house. However, due to the water seal that effectively prevents odours and flies from coming back up the pipe, pour flush pans can also be installed inside the house. This can on one-hand side help in reducing construction costs (shared walls and roof) and increase user’s comfort (no need to leave the house for visiting the toilet).

Operation & Maintenance

Because there are no mechanical parts, pour flush toilets are quite robust and rarely require repair. Despite the fact that it is a water-based toilet, it should be cleaned regularly to maintain hygiene and prevent the buildup of stains. To reduce water requirements for flushing and to prevent clogging, it is recommended that dry cleansing materials and products used for menstrual hygiene be collected separately and not flushed down the toilet.

Urine diversion pour-flush pans

(Adapted from: WATERAID 2008)

The urine diversion pour-flush pan, also known as wet ecosan pan, is essentially a modification of the conventional pour-flush squatting pan, but separates urine and faeces. This type of pan is especially useful in areas where plenty of water is easily available and handling of faeces is socially undesirable.
Both the pans have two holes - one for faeces and one for urine. The area between the holes is sloped towards the faeces hole as the water is collected together with the faeces. See also urine diversion components.

 WAFLER (2009)

Nepalese urine-diversion squatting pan made from cement (left) and fibreglass (right) (water seal not shown). Source: WAFLER (2009)
 

At a Glance

Working Principle

A pour-flush toilet is like a regular flush toilet except that instead of the water coming from the cistern above, it is poured in by the user. It can be constructed inside or outside the house but requires a adapted treatment for the outflowing blackwater (e.g. twin-pits, septic tanks, biogas settler).

Capacity/Adequacy

The water seal is effective at preventing odours and it is appropriate for those who sit or squat (pedestal or slab) as well as those who cleanse with water. It is only appropriate when there is a constant supply of water available.

Performance

Depends strongly on user’s operation and maintenance.

Costs

Depends on material used (concrete, fibreglass, plastic, stainless steal, etc.) and transport distance.

Self-help Compatibility

In general, can not be manufactured locally.

O&M

Because there are no mechanical parts, pour-flush toilets are quite robust and rarely require repair. Should be cleaned regularly to prevent the build up of organics and or/stains.

Reliability

High, if maintained well.

Main strength

Water seal effectively prevents odours.

Main weakness

Requires a constant source of water.

Applicability

The water seal is effective at preventing odours and it is appropriate for those who sit or squat (pedestal or slab) as well as those who cleanse with water. It is only appropriate when there is a constant supply of water available. The pour-flush toilet requires (much) less water than a traditional cistern flush toilet. However, because a smaller amount of water is used, the pour-flush toilet may clog more easily and thus, require more maintenance.
If water is available, this type of toilet is appropriate for both public and private applications. Pour-flush toilets are adequate for almost all climates.
 

Advantages

  • The water seal effectively prevents odours
  • The excreta of one user are flushed away before the next user arrives
  • Suitable for all types of users (sitters, squatters, wipers and washers)
  • Low capital costs; operating costs depend on the price of water

Disadvantages

  • Requires a constant source of water (can be recycled water and/or collected rain water)
  • Cannot be built and/or repaired locally with available materials
  • Requires some education to be used correctly

References Library

EVELEIGH, J.D. (2002): Bogs, Baths and Basins: The Story of Domestic Sanitation. Gloucestershire: Sutton Publishing. URL [Accessed: 24.08.2010].

HARVEY, P.; BAGHRI, S.; REED, B. (2002): Emergency Sanitation: Assessment and Programme Design. Loughborough: Water, Engineering and Development Centre (WEDC). URL [Accessed: 21.02.2011].

MARA, D. (1996): Low-cost Urban Sanitation. United Kingdom: Wiley.

ROY, A.K.; CHATTERJEE, P.K.; GUPTA, K.N.; KHARE, S.T.; RAU, B.B.; SINGH, R.S. (1984): Manual on the design, construction and maintenance of low-cost pour-flush water seal latrines in India. (= TAG technical note; no. 10). United Nations Development Programme (UNDP) and World Bank. URL [Accessed: 01.06.2010]. PDF

SHITAL CERAMIC WORKS (Editor) (2005): Shital Ceramic Works Company. SHITAL CERAMIC WORKS. URL [Accessed: 29.07.2010].

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2013): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag).

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

Further Readings Library

Reference icon

HARVEY, P.A. (2007): Excreta Disposal in Emergencies. A Field Manual. Leicestershire: WEDC Loughborough University. URL [Accessed: 29.07.2011]. PDF

In this manual existing, innovative and new technologies and approaches for excreta disposal in emergency situations are investigated. It provides practical guidance on how to select, design, construct and maintain appropriate excreta disposal systems to reduce faecal transmission risks and protect public health in emergency situations.


Reference icon

MARA, D. (1996): Low-cost Urban Sanitation. United Kingdom: Wiley.

This book covers the public health, technical, socioeconomic, sociocultural and institutional aspects of sanitation in towns and cities of developing countries. The text features excreta-related diseases and the use of sanitation to reduce their transmission. The sanitation technologies covered in detail are VIP latrines, pour-flush toilets, septic tanks, settled sewerage and simplified sewerage, with additional chapters on sullage disposal, pit emptying, and sewage treatment and reuse. Sociocultural constraints on sanitation systems and their socioeconomic costing are described, together with hygiene education, which is essential in order to achieve maximum benefits to health. The text also explains how to choose the most appropriate sanitation option for a given low-income community. Finally, institutional aspects are reviewed, including effective sanitation programme planning, monitoring and evaluation.


Reference icon

MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010): How to Select Appropriate Technical Solutions for Sanitation. (= Six Methodological Guides for a Water and Sanitation Services' Development Strategy, 4). 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.

See document in FRENCH


Reference icon

TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; ZURBRUEGG, C. (2013): Compendium of Sanitation Systems and Technologies. 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag).

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


Case Studies Library

Reference icon

MORGAN, P. (2007): Available Sanitation Technologies for Rural and Peri-Urban Africa. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

The presentation allows for a good overview on existing types of pit latrines in Africa, but also on other types of sanitation technologies such as the conventional flush toilet, the pour flush toilet, and the urine diversion dehydration toilet (UDDT).


Reference icon

WAFLER, M. ; HEEB, J.; STAUB, A.; OLT, C. (2009): Pour-flush toilets with biogas plant at DSK Training Institute. Gujarat, India - Draft. (= SuSanA - Case Studies). Eschborn: Sustainable Sanitation Alliance (SuSanA). URL [Accessed: 25.04.2010]. PDF

The project described aimed at avoiding manual scavenging of faecal products and at improving the sanitation situation at the Navsarjan Vocational Training Institute. Now greywater is separately treated and reused in the garden while the urine and faeces (blackwater) are directly introduced into a biogas plant. Digested sludge is dried on basic drying beds and used as compost for the garden. UDDTs were also installed. The concept was implemented and evaluated for its social and cultural acceptability, sustainable and hygienic safety.


Reference icon

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.


Awareness Raising Material Library

Reference icon

NWP (Editor) (2006): Smart Sanitation Solutions. Examples of innovative, low-cost technologies for toilets, collection, transportation, treatment and use of sanitation products. (= Smart water solutions). 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.


Training Material Library

Reference icon

EAWAG/SANDEC (Editor) (2008): Sanitation Systems and Technologies. Lecture Notes . (= Sandec Training Tool 1.0, Module 4). Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). PDF

Lecture notes on technical and non-technical aspects of sanitation systems in developing countries.


Reference icon

REED, B.; SHAW, R. (2013): Latrine Slabs. (= WEDC Posters, 1). London: Water, Engineering and Development Center (WEDC). URL [Accessed: 07.08.2013]. PDF

This poster is part of the series of Water, Sanitation and Hygiene posters designed by the Water, Engineering and Development Center of Loughborough University.


Reference icon

REED, B.; SHAW, R. (2013): Simple Pit Latrines. Poster. (= WEDC Posters, 10). London: Water, Engineering and Development Center (WEDC). URL [Accessed: 28.08.2013]. PDF

This poster is part of the series of Water, Sanitation and Hygiene posters designed by the Water, Engineering and Development Center of Loughborough University.


Important Weblinks

http://www.youtube.com [Accessed: 17.10.2013]

This is a lecture By Duncan Mara on Pour Flush Toilets for use in developing countries.

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.