Creating Arborloo Composting Toilets

From April to July 2025, eight arborloo toilets were built for new arrivals in Nakivale Refugee Settlement, Uganda, by refugee-led UNIDOS Social Innovation Center in partnership with Re-Alliance. This four-month initiative focused on training eight newly arrived refugee households to construct these low-cost systems using recycled and locally available materials. Arborloos are a composting toilet model which use a movable upper structure on top of a pit which, once full, can be topped with soil and planted with a tree or perennial plant guild. The upper structure is then moved on to a newly dug pit, and the cycle continues. See the reference illustration below as an example, and read more in this case study here (including full costings).

The urgent need for this intervention stemmed from a large increase of people fleeing intense conflict in the Democratic Republic of Congo, and arriving to Uganda. This rapid displacement had caused a severe shortage of proper sanitation facilities across Nakivale. Before the project, it was common for five households to share a single, poorly maintained pit latrine. This crisis has driven open defecation and contaminated local water sources, heightening the risk of disease outbreaks. The Arborloo addressed this environmental and public health crisis by providing an ecologically-friendly, cost-effective and easily-built alternative.

An Arborloo is a simple, low-cost toilet designed to couple daily human sanitation with ecological restoration. It utilises a shallow pit dug to a depth of 1 to 1.5 metres to optimise organic composting conditions. Once the pit is filled, the lightweight toilet structure is moved to a new location. A tree, or perennial plant guild, is then planted directly into the nutrient-rich humanure left behind. Because of this shallow design, the Arboloo is uniquely suited for household or shared-family use rather than crowded communal areas.

Arborloos transform human 'waste' into valuable soil nutrients that accelerate tree growth and deliver multiple compounding benefits. On a human level, it provides immediate, safe sanitation. On an ecological level, the emerging trees stabilise fragile soils, provide vital cooling, sequester carbon, and boost biodiversity. Furthermore, as these trees mature, they become a direct resource for families. For example, the trees can provide agricultural mulch, coppice materials, small twigs for rocket stoves, and even foods from trees (not annual crops, which in some rare situations may be able to absorb pathogens from the humanure).

Solutions designed with and by the community are far more likely to be maintained and scaled effectively. By choosing low-tech, locally adapted solutions, the community created a resilient sanitation system that will continue to protect public health and restore the local environment.