Fill and Cover / Arborloo

To decommission a pit, it can simply be filled with soil and covered. Although there is no received benefit, the full pit poses no immediate health risk and the contents will degrade naturally over time. Alternatively, the Arborloo is a shallow pit that is filled with excreta and soil/ash and then covered with soil; a tree planted on top of the nutrient-rich pit will vigorously grow.

When a single pit or a single VIP is full and cannot be emptied, "fill and cover", i.e., filling the remainder of the pit and covering it is an option, albeit one with limited benefits to the environment and the user.

The Arborloo is a shallow pit on which a tree can be planted after it is full, while the superstructure, ring beam and slab are moved to a new pit. Before the Arborloo is used, a layer of leaves is put on the bottom of the empty pit. A cup of soil, ash or a mixture of the two should be dumped into the pit to cover excreta after each defecation. If they are available, leaves can also occasionally be added to improve the porosity and air content of the pile. When the pit is full (usually every 6 to 12 months), the top 15 cm is filled with soil and a tree is planted. Banana, papaya and guava trees (among many) have all proven to be successful.

Design Considerations

An Arborloo is only an option if the site is suitable for a tree to grow. Therefore, when selecting the pit location, users should already take the space and site conditions required for a new tree into account (e.g., distance to houses).

A shallow pit, about 1 m deep, is needed for an Arborloo. It should not be lined as any lining would prevent the tree or plant from properly growing.

A tree should not be planted, however, directly in the raw excreta. It should be planted in the soil on top of the pit, allowing its roots to penetrate the pit contents as it grows. It may be best to wait for the rainy season before planting it if water is scarce.

Appropriateness

Filling and covering a pit is an adequate solution when emptying is not possible and when there is space to continuously dig new pits.

The Arborloo can be applied in rural, peri-urban, and even denser areas if enough space is available.

Planting a tree in the abandoned pit is a good way to reforest an area, provide a sustainable source of fresh fruit and prevent people from falling into old pit sites.

Other plants such as tomatoes and pumpkins can also be planted on top of the pit if trees are not available.

Depending on the local conditions, however, the content of a covered pit or Arborloo could contaminate groundwater resources until it is entirely decomposed.

Health Aspects/Acceptance

There is minimal risk of infection if the pit is properly covered and clearly marked. It may be preferable to cover the pit and to plant a tree rather than emptying it, especially if there is no appropriate technology available to remove and treat the faecal sludge.

Users do not come in contact with the faecal material and, thus, there is a very low risk of pathogen transmission.

Arborloo demonstration projects that allow for the participation of community members are useful ways to display the ease of the system, its inoffensive nature, and the nutrient value of human excreta.

Operation & Maintenance

A cup of soil and/or ash should be added to the pit after each defecation and leaves should be periodically added. Also, the contents of the pit should be periodically levelled to prevent a cone shape from forming in the middle.

There is little maintenance associated with a closed pit other than taking care of the tree or plant. Trees planted in abandoned pits should be regularly watered. A small fence of sticks and sacks should be constructed around the sapling to protect it from animals.

References

Further Readings

  • Cover image of a reference book or miscellany.

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

    This is the Arabic version of the Compendium of Sanitation Systems and Technologies. The 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.

    MORGAN, P. (2004): The Arborloo Book. (pdf presentation). Stockholm: Stockholm Environment Institute. PDF

    This booklet describes how to construct an arborloo toilet, which is both low cost and easy to make.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2004): The Arborloo and growing trees. (pdf presentation). Stockholm: Stockholm Environment Institute. PDF

    This extract describes how to create a low-cost and well functioning arborloo and contains lots of information on how to plant trees in the closed pit.

  • Cover image of a reference book or miscellany.

    MORGAN, P.; EcoSanRes (Editor) (2007): Toilets That Make Compost . Stockholm: Stockholm Environment Institute. PDF

    This book describes in an easy-to-understand and picture-based way how to construct three different low cost sanitation solutions, namely arborloos, fossa alterna and urine diversion toilets.

  • Cover image of a reference book or miscellany.

    EcoSanRes (Editor) (2008): Toilets That Make Compost. Factsheet. (pdf presentation). Stockholm: Stockholm Environment Institute. PDF

    This information sheet summarises the Peter Morgan publication under the same name on two pages. It describes three types of simple and affordable composting toilets: Two types of shallow pit toilets (arborloo) and the urine diverting toilet.

  • 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.

    TOUBKISS, J. (2010): How to Manage Public Toilets and Showers. 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).

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2011): Trees as recyclers of nutrients present in human excreta. Zimbabwe: Aquamor Pvt Ltd.. URL [Accessed: 19.06.2013]. PDF

    his report clearly indicates that trees of various types can benefit greatly from the nutrients derived from human excreta and the methods of transferring the nutrients can vary somewhat. These vary from direct uptake from an unlined pit, a lined pit, by various methods of urine application and also from the seepage from soakaways linked to septic tanks of various types.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2010): Methods of Using "Toilet Compost" in Agriculture. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This document gives a simple overview over toilet compost, its preparation and fields of application.

Case Studies

  • Cover image of a reference book or miscellany.

    HERBERT, P. (2010): Rapid Assessment of CRS Experience With Arborloos in East Africa. Baltimore: Catholic Relief Service. URL [Accessed: 03.01.2011]. PDF

    This rapid assessment reviewed sanitation activities by Catholic Relief Services in East Africa, in particular the promotion of the Arborloo – an innovative latrine designed to help achieve sustainable and scalable sanitation improvements in rural Ethiopia, South Sudan, Kenya and Uganda. The assessment explored the factors affecting Arborloo acceptance and sustainability, the scope and approaches for scaling up the latrine in these countries and in Tanzania, as well as opportunities to foster links between community and school sanitation.

  • Cover image of a reference book or miscellany.

    SAYRE, E.; WAND (Editor) (2008): Practical Experiences in implementing Ecological Sanitation during Extreme Dry Regimes . Philippines: Water, Agroforestry, Nutrition and Development Foundation. PDF

    This presentation of WAND-Foundation provides information on experiences achieved in the field of implementing various technologies of ecological sanitation in the Philippines. It contains a variety of local technologies (including arborloos), financing mechanisms and emerging opportunities.

  • Cover image of a reference book or miscellany.

    CRS (Editor) (2012): Promoting Ecological Sanitation in Ethiopia through the Arborloo Latrine. Baltimore: Catholic Relief Services (CRS). URL [Accessed: 22.02.2012]. PDF

    The ArborLoo is successful in Ethiopia because: its design addresses past obstacles to sanitation; its construction is simplified, reducing financial outlay and construction costs; it emphasizes marketing and participatory efforts; and it increases the output of additional organic fertilisers.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2007): The Arborloo Book for Ethiopia. How to Make a Simple Pit Toilet and Grow Trees and Vegetables. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 20.06.2013]. PDF

    This booklet describes how to make a toilet which is both low cost and easy to make. Builders and artisans are not required, once the householder has learned the basic methods of construction.

  • Cover image of a reference book or miscellany.

    MORGAN, P. (2005): Ecological Sanitation in Southern Africa. Many Approaches to a Varied Need. Stockholm : Ecological Sanitation Research (EcoSanRes), Stockholm Environment Institute (SEI). URL [Accessed: 21.06.2013]. PDF

    This document describes the ecological sanitation situation in South Africa, focussing on the range of technological options, promotional methods and recycling methods and the problem areas.

  • Cover image of a reference book or miscellany.

    MUELLEGGER, E. (Editor); LANGEGRABER, G. (Editor); LECHNER, M. (Editor) (2010): The ROSA Project. Vienna: Ecosan Club. URL [Accessed: 01.07.2013]. PDF

    The ROSA project stands for Resource-Oriented Sanitation concepts for peri-urban areas in Africa. This Sustainable Sanitation Practice (SSP) issue contains the following contributions: 1. Introduction to the ROSA Project, 2. From Pilot Units to Large-Scale Implementation - Ethiopia, 3. Implementation of UDDTs at Schools - Kenya, 4. Urban Agriculture for Sanitation Promotion, 5. Operation an Maintenance in Practice, 6. Experiences from Strategic Sanitation Planning, 7. Main Findings and Main Achievements.

  • SUSANA (2009): Low-cost Arborloo with separate collection of urine in EcoPees. SuSanA on Flickr. SuSanA. URL [Accessed: 09.06.2011].

Awareness Material

  • Cover image of a reference journal article.

    TUHUS-DUBROW (2008): Waste? Not. In: The Boston Globe.URL [Accessed: 21.02.2010]. PDF

    Critical article on conventional end-of-pipe wastewater approaches, introducing some alternatives such as biogas digester, arborloos or the fossa alterna.

  • 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.

Training Material

Important Weblinks