Nakivale Arboloo Toilets: Growing Trees from waste

Mary Mellett
17 hours ago
4 min read

*Illustration of an Arborloo by Tanya Haldipur*

Project Overview

8 arborloo toilets were built for shared household use for new arrivals in Nakivale Refugee Settlement, Uganda by refugee-led UNIDOS Social Innovation Center, in partnership with Re-Alliance.

When full, these portable toilets will be moved for continued use and trees will be planted on the full pits.

The project showed the potential for lower cost arboloos to be rapidly built to respond to influxes of new arrivals. Beyond providing a safe, dignified toilet, arboloos compost wastes in-situ, building soils and feeding sapling trees such as mango, guava or banana, planted above. Because they use shallow pits and are simple to construct, they can be built and maintained by the local community with very low maintenance costs. Because wastes are composted in-situ, there is no secondary handling, reducing risks to health.

UNIDOS trained eight households of new refugee arrivals, all identified as Persons with Special Needs, to construct and maintain the lower-cost arborloo toilets using locally available materials. They continue to support the use and maintenance and will help households move the toilets and plant trees when they are full.

What is an Arborloo?

*Sectional drawing of a relocated arborloo, by Tanya Haldipur*

The arborloo is a simple, lower-cost toilet that integrates sanitation with tree planting. It is a shallow pit toilet, typically dug to a depth of between 1 and 2 meters which promotes the conditions for composting. When the pit is full, a new pit is dug nearby and the toilet is moved. A tree is planted on the full pit. As a pit toilet, they are not suitable for all locations including areas close to natural water sources and places with rocky ground. Because pits are shallow, they only have the capacity for household, or shared household use, rather than communal latrines as the number of users must be controlled.

The Arborloo Process

Construction: The user first digs a shallow pit. A portable toilet consisting of a ring beam, slab, and superstructure is placed over this pit.
Use: The pit is used as a standard pit latrine. Users are encouraged to cover the excreta with soil, ash, and/or leaves. It is important to train people not to add excess water or put rubbish down the pit.
Relocation & Regeneration: Once the pit is full, typically between 6 and 12 months, the toilet superstructure is moved to a newly dug pit nearby.
Planting: A beneficial tree, such as mango, guava, paw paw, banana, or mulberry, is then planted directly on top of the filled, nutrient-rich pit.

The Multiple benefits of Arborloos

The Arborloo system turns human waste into compost, allowing the tree roots to tap into the nutrients to boost growth. This process delivers multiple long-term benefits to the community:

*Paulinho from Unidos and representatives from OPM visit a participant who is using and maintaining the arboroo. The structure is timber and clad with light-weight metal sheeting*

Sanitation and protection: Provides immediate, dignified, and safe sanitation. Because the toilets are for households rather than communal latrines, they are closer to where the users live and safer for women and girls.
Ecology: Trees stabilise soils, provides shade and cooling, sequester carbon, increases biodiversity. The compost boosts soil health and water-holding capacity.
Resources: Over time trees can provide food, mulch and coppice materials for households

The project successfully built eight arboloo toilets, provided sanitation and maintenance education to the selected households, and will engage households going forward in continued M&E, moving the toilets and tree-planting.

Challenges

The final report highlighted two primary challenges:

High Demand: The demand for the toilets significantly exceeded the supply. It is important that toilets are not over-used by too many people so padlocks on the outside of the toilets were needed to ensure the toilets were kept for household, rather than communal use.
Higher materials costs: Seasonal changes led to an increase in the price of construction materials, impacting the initial budget.

Despite these challenges, the project demonstrated a successful, replicable model for providing resilient and regenerative solutions to communities by integrating sanitation, hygiene promotion, and tree planting.

How much does an Arborloo cost?

The Nakivale project used lower-cost, locally sourced materials to maximize the sustainability and replicability of the design. Materials for the superstructure can be varied according to context.

The cost of materials and transportation for a single Arboloo toilet in Nakivale:

Item/Material	Unit Cost (UGX)	Total Cost (UGX)	Total USD cost
Iron Sheets	24,000	192,000	55
Rebar x 10	35,000	140,000	40
Wood	12,000	84,000	24
Cement	40,000	80,000	23
Wheelbarrow	15,000	60,000	17
Kazao Sand	20,000	60,000	17
Rebar 8	15,000	45,000	13
Nail (roof, wood & sheet)	6,000	30,000	9
Padlock	5,000	5,000	1
Sub-Total (Materials)		696,000	199
Transportation of Materials (per toilet)	80,000	80,000	23
Total Unit Construction Cost (Materials + Transport)		776,000 UGX	222 USD

The total project budget also included crucial non-material expenses, including 580,500 UGX for project training costs, and 1,005,332 UGX for Unidos staff wages.