Composting toilets

As a group of sustainably-minded Cal Poly students, our goal is to work with Aid Africa to implement new toilet designs in rural Ugandan villages, for the purpose of introducing composting practices into existing family compounds.


In Uganda, a majority of people have no access to a toilet, with only 34% of people having some access to improved sanitation in rural areas. About 84% of the population of Uganda lives in rural areas, and typically, residents will “handle their business” by stepping outside the family compound and squatting in the plants, both for increased privacy and to keep fecal matter away from living areas.

Screen Shot 2017-05-23 at 9.15.32 PM.png
Figure 1: Uganda’s Improved Sanitation in rural areas (1990-2010)

According to Peter Keller, executive director of Aid Africa, the largest percentage of crimes against women and children occur when traveling outside of their compound, often during these bathroom trips. Due to this, it is our hope that by implementing a bucket toilet within the compound itself, the risk and amount of crimes committed will decrease against these populations. It is also our desire, by introducing a bucket-style toilet, that such facilities will help to provide a new source of fertilizer for personal crops since their farmland tends to be within about one-half of a kilometer.

Additionally, not only is Uganda in need of proper sanitation, but other developing countries such as Mexico and India with 79% and 23% improved sanitation access in rural areas in 2010, respectively. In India women have taken the matter into their own hands by demanding men to build them toilets as read in this NPR article. The affordable bucket-style toilet has the potential to help improved sanitation practices not just in Uganda but all over the world.


Figure 2: The Republic of Uganda

The Republic of Uganda is a landlocked country in eastern Africa. With a total population of 39 million people, and covering an area of 241,000 square kilometers, it is the 35th most populous country and 81st largest country on Earth, respectively. Located on the East African Plateau, the country is mostly comprised of flat grasslands, save for the Rwenzori mountain range on the country’s extreme western border with the Democratic Republic of the Congo. Uganda has a diverse landscape, but due to its location on the Equator, the country has a mainly tropical climate, with two highly rainy seasons from March until May and from September until November; due to this, the country’s landscape is mainly shaped by its large natural bodies of water. These include the “Great Lakes” of Albert, Edward, and Victoria; smaller localized lakes such as Kwania and Kyoga; and the two main rivers through the country, the Victoria Nile and the Albert Nile.

Per capita, Uganda is one of the poorest nations on Earth, with average yearly income being around $1,621/year per resident. According to the World Bank, around 38% of Ugandans live on less than $1.25 per day. As a result of this level of poverty, levels of education and life expectancy are low. On average, men average around six years of school in their lifetimes, while women spend only three years in any type of educational setting. Due to this, women tend to get married around twenty years old. Average life expectancy in the country is 60 years old, considerably lower than the world average of 71 years. Additionally, 5.95% of children under the age of five die every year in the country.


Figure 3: Aid Africa Staff

Aid Africawas originally founded in 2004, with its first project taking place in internally displaced person (IDP) camps in Lira, Uganda, the following year. Originally concerned with making stoves for families in the camp to decrease respiratory illness and allow resources to be used more efficiently, the group expanded its goals toward building wells to ensure access to clean water sources, planting trees for further resource usage, and arranging transport to local hospitals to decrease infant illness and fatalities. These efforts to expand were further spearheaded in 2009, after the Ugandan government began closing the IDP camps and relocating residents to their ancestral homes. Aid Africa eventually moved their base of operations to Gulu, where they continue their collaborations and hope to provide healthy, sustainable practices to the Ugandan people.

As noted above, Aid Africa currently undertakes multiple types of projects in the Gulu region. The group hopes to plant almost one million trees across northern Uganda, to replenish native vegetation populations destroyed by war and a refugee crisis in the region. It is hoped that these new trees will provide wood needed to build housing, fresh fruit for nutrition, and shady areas during summer months. Additionally, the group is working with native Ugandans to build designated wells in village areas. This is undertaken not only to ensure access to unpolluted water, but also to lessen the time required for women and children to gather water for their families.


We are suggesting the implementation of a pit latrine, in order to follow the “cradle-to-cradle” methodology of waste system design. In this system, instead of being buried as unusable waste, fecal matter is collected and converted into fertilizer and compost, which can then be used to cultivate further crops.

The decision matrix below shows a couple of different designs we have considered for our toilet. More information about the different composting toilets and briquettes can be seen in the following Composting toilets and Briquettes. Ultimately, we are planning to move forward with the bucket design due mainly for its feasibility and low capital cost.

Criteria Capital Cost Operations and Maintenance Environmental Impact Feasibility Cultural Acceptance Education Weather resilience Total Out of perfect score
Weight 10 10 10 20 10 20 10 90
Absolute Weight (%) 11.11% 11.11% 11.11% 22.22% 11.11% 22.22% 11.11% 99.99% 100%
1 Bucket Design 9 5 10 8 6 7 7 7.44 74%
2 Carousel Design 4 4 9 4 7 5 4 5.11 51%
3 Briquettes 1 2 3 3 3 7 3 3.56 36%
4 Solar Toilet 5 4 9 4 7 6 5 5.56 56%
5 Guatemalan Toilet 6 7 9 6 4 7 7 6.99 70%
6 Latrine 8 5 3 9 6 8 7 6.99 70%

Typically, when working with technology for a different group of people, we have to understand the culture and society of the targeted community. In Uganda, it is typical for the women to collect the firewood, rear the children, cook the meals, collect water, and farm the land. While the women work about 15 hours per day, the men do about 9 hours/day. Each family compound has about three generations that are housed in different huts by generation as well as several huts with other uses, such as for cooking or storage. The grandparents have one house, the parents another, and another for the children. People tend to live in compounds/family farms that are in a kind of circle that is about 100 feet in diameter, and each person steps out of the ring of land to use the bathroom.

Could you provide an approximate scale of 100 feet on the map or state the length of the side of the square you have drawn?

Uganda Family Compound.jpg
Figure 4: A typical family compound in Uganda. They are approximately 100 feet in diameter.

Screen Shot 2017-05-02 at 10.39.47 AM.jpg
Figure 5: Aerial view of family unit near Budaka, Uganda.(1°00’55.8″N, 34°00’38.6″E)

1°00’55.8″N 34°00’38.6


Introducing the implementation of bucket toilets in Uganda comes with a slew of potential issues. Firstly, human waste is a sensitive subject. Defecating and urination are typically done in private and can have various social stigmas associated with it. We need to be considerate during this project because asking people in Uganda to adopt bucket toilets without adopting them ourselves might come across as patronizing. It is difficult to ask anyone to change their customs and even more difficult because of the subject matter. Secondly, we need to address cleanliness. Using a bucket toilet and urine trap comes with a certain level of risk that we would like to minimize as much as possible. That risk involves missing the toilet or urine trap while using the restroom, flies and cleaning the device. We are going to do our best in our design to ensure that the urine and feces go where they are supposed to go in a pretty foolproof way. We designed this bucket toilet with the people of Uganda in mind and since they squat when they use the restroom. We are concerned that cleaning the device will be unappealing or not done properly since the bucket and urine trap need to be washed and left out to dry, but as it is wet in Uganda so often, it might be hard to get it completely dry because the rainy seasons are long. The compost also needs to be able to dry out, so this may pose a problem as well. Another issue we have to tackle is education. We need to be able to convince the people in Uganda that even though composting has mostly long-term benefits rather than short-term ones, it is still a useful practice. It might be difficult to convince the people of Uganda to use vegetative material for composting as they burn the vegetation as fuel and any vegetation left lying around might attract deadly snakes.


When designing the bucket toilet, we carefully took into consideration the materials. We wanted the Ugandan people to have access to affordable materials in order for them to be able to build their own bucket toilet or to even start a business of selling bucket toilets.

For the scope of this project we decided to build a platform for the bucket toilet in order to make the bucket toilet transferable and to make it easy for the Ugandan people to squat when going to the bathroom. The design below separates the feces and urine in order to keep smell to a minimum since urine smells worse than the feces. It also serves to prevent the urine from making the feces anaerobic. Aerobic conditions in the feces are desirable to maximize the growth of thermophilic bacteria which helps compost the feces. In order to maximize the amount of feces entering the bucket, we decided to build the urine trap outside the bucket.

We took into consideration the children’s safety when designing the step. We wanted to decrease the danger of children injuring themselves when going to the restroom on their own, so a step was designed for them to reach the top of the platform. An elevated platform was introduced beneath the bucket to elevate the bucket so that it would be easier to use. A lid was designed to go over the bucket to keep the flies out because they tend to lay their eggs in feces and they could carry disease-causing pathogens.

The Uganda people have limited access to water, so we design a toilet that minimizes the amount of water to clean the urine trap. This was accomplished by reducing the distance of the urine entering the trap into the storage container. We eliminated a urine and substituted with a large funnel that was reshaped to fit against the curvature of the bucket. Since there is a smaller distance, the concern for urine crystallization is also reduced.The top of the lid was painted with water proof paint in order to reduce the condensation on the wood.

The composting will occur once the bucket is filled, typically every other week. The urine container may be emptied as frequently as needed and may be used directly to water crops. Education will play a vital role in teaching the Ugandan on how to maintain their composting pile in order to fully utilize it in their family farms. The composting pile will be protected from the rain by using a tarp, the tarp will prevent the composting pile from getting wet which will ensure that composting is occurring.

Figure 6: Initial Design for Bucket Toilet

Top View.jpg
Figure 7:Schematic of the top-view of the bucket toilet with the lid opened.

Cost of the Prototype:

Materials Cost ($)
Wood 60
Bucket 3
Rubber Funnel 5
Urine Collector (gas can) 15
Hinges and Mending Braces 25
Rubber Stripping 7
Total 115

Construction Phase:

During the construction phase we found out the following:
– The platform could of been a lot smaller which will decrease the amount of wood
– The step is not necessary since the platform is low enough for children to climb
– Original structure support will not work therefore we improvised on the support on the main wood structure
– We could of lower the cost if we use nails instead of screws with mending braces in order to make it affordable for the Ugandan
– We build the platform too high for the bucket so we needed to build a height structure for the bucket so the lid can completely protect the bucket

Below are a few pictures of our prototype:

Figure 8: Bucket with Urine Trap

Figure 9: Prototype structure with bucket toilet


Figure 10: Finalized support design (x-ray with the top section removed)

Side View.jpg
Figure 11:Side-view of the bucket toilet design with the bucket toilet and urine trap attached. The lid is closed in this schematic.

Figure 12: Completed Prototype

Once finishing our prototype we realized the following improvements can be accomplished in order to optimize the design:
– Adding additional support on the center of the platform, currently there is no support for that area
-We can find a more affordable urine trap that essentially works the same as the 2.5 gallon gas can we purchase
-We can minimize the cost and the amount of materials used by utilizing bricks or cinderblocks as a platform or even the ground. This improvements can essentially lower the cost from $115 to $27, about 77% lower cost than our original prototype.

Materials Cost ($)
Bucket 3
Funnel 5
Urine Collector (gas can) 15
Rubber Stripping 1
Lid (wood) 3
Total 27


For the scope of our project, we ultimately wanted to build something with familiar materials, such as wood and nails. We realize that in Uganda, there may be a greater potential for adoption if this system was made even more simpler. Aforementioned, utilizing bricks as a platform or even digging a pit for the bucket and urine track would be simple to implement. A detachable lid that was connected to the bucket would also be useful in the case that the wooden platform isn’t built.

None of us had any experience designing something and having an opportunity to build it. As a team, we got to experience first-hand what does it mean to have a bad design and learning to fix it as we continued with construction. It was definitely a “learn as you go along” type of project. In the end, we began to understand what we could have done differently and how to better construct this bucket toilet system.



Our bucket toilet team having fun at the Student Experimental Farm.
Left to Right:Maddy Ciulla, Child DevelopmentSam Ricklefs, City & Regional PlanningDenise Man, Environmental EngineeringIrma Marin, Environmental Engineering