Dar es Salaam is one of the fastest-growing cities in Africa. The population is expected to grow so much, that Dar es Salaam is projected to be the second-largest city by population in the world by 2100, with a predicted population of 76 million, (according to World Population Review). The annual growth rate is expected to average 4.39% through the year 2020. In the next three years, the population is expected to reach 5 million.

With this rate of rapid urbanization and population increase with 70% of its people living in informal settlements, waste management (the solid waste in particular) is a serious problem. Concurrent with recent socio-economic development, the quantity of solid waste generated has increased at a rapid rate. There have been policies and laws to guide solid waste management in Dar es Salaam but it has never been effective, such that people tend to dump solid waste any way they can as there is no proper and effective way of waste collection

Flooding in Dar es Salaam is mainly caused by blockage of the waterways, i.e. rivers, drains, streams, ditches, etc. People dump solid waste and cause blockages. Materials like metal, plastics, and sometimes natural debris are being dumped causing flooding. Without proper and effective ways of managing waste, floods will continue to overwhelm the drainage system, overflowing into communities, In Tabata most houses are flooded due to blocked drains.

HOT, with their local partner OMDTZ and supported by the World Bank, decided to pilot a mapping activity in an informal settlement (Tabata Ward) similar to what they have done in formal areas (Mchafukoge and Kisutu wards) and create datasets that may help trash company collectors to effectively collect trash from their clients.

HOT and OMDTZ partnered with Joshemi Company Limited, a company dealing with trash collection in Tabata. Tabata is an administrative ward in the Ilala District. According to the 2002 census, the ward had a total population of 46,228. The ward is comprised of eight subwards [Mandela, Kisiwani, Tenge, Msimbazi Mama, Msimbazi Magharibi, Tabata, Matumbi and Mtambani]. It is mainly comprised of informal settlements and is found along the Msimbazi River valley (the main flooding river in the city).

Joshemi Company has created a weekly schedule for every subward where they have to collect the solid waste. Residents and owners of business firms must pay a certain amount to the company depending on the size of the trash bag.

The Aim of Mapping

JCL needed to know the number of clients as it was very difficult to track them all, revenue flow and an effective feedback system on services provided by the company. The aim was shifting JCL’s analogue system of trash collection to a digital system by providing them with their own maps of clients’ locations and a system of tracking them. This way, JCL would improve their services to clients, increase their revenues and create an effective waste collection mechanism.


Pilot mapping was conducted in two subwards of Tabata Ward (Msimbazi Magharibi and Msimbazi Mama). As our policy has always relied on open source software, we used OpenDataKit (ODK) Collect and OpenMapKit (OMK) – an extension of ODK which is a free and open android application for data collection. The team worked with revenue collectors to conduct mapping as they have a better understanding of the area to ease the process of data collection.

Field data collection. Msimbazi subward, Tabata. 

The team prepared an excel sheet with ward, subward name, name of mjumbe, location together with client information including name, phone number, month, amount and receipt ID. To ease the process, fake ID numbers were created to identify clients’ houses because in informal settlements there are no house numbers. The sheet was then printed and given to the mappers for data collection, data cleaning and processing.

Fake house ID numbers are given to identify houses (The layers  of buildings visualized on OMK application)

The team training JCL on how to use ODK and OMK in the field at Msimbazi Mama, Tabata

Outcomes and Impact

The company has a full understanding of the location and number of clients and challenges that their clients face. As the company now knows the number of clients, they plan to improve their services by having more trucks and more trips. Before mapping, they were only serving 300 clients, and after mapping, they have come to a realisation that there are 2000 clients that need to be provided with the service. This will not only increase the company’s revenue but also improve service to the citizens and keep the ward clean.

Johanes Petro, a mapping supervisor at OMDTZ is very positive about the initiative. He said,

“This initiative will lead to improved waste management as the company now knows they have many clients, they may double or triple services and the clients will be serviced accordingly. In turn, this will increase revenue to the company and improve services to citizens”. He added, “There is a need to replicate this process to all informal settlements in Dar es Salaam which will contribute to a sustainable and clean city as the system created is user-friendly”


Until now, our team is working with the revenue collectors to capacitate them on data use and help to establish the link between the excel sheet prepared and established layers of OMK.

Challenges in Data Collection

The team started the process of data collection with the revenue collectors, but the revenue collectors were a bit hesitant to provide full collaboration as they were fraudsters and printing counterfeit receipts. So they believed if the company is provided with reliable data and the exact number of clients under service, their stealing methods would be revealed. So they did not collaborate and the company fired them.

Mappers had to shift from working with revenue collectors to shina leaders, famously known as “wajumbe” – the hyper-local leaders (the most granular level of administration that exists in Tanzania). These leaders are responsible to administer a small cluster of houses ranging from 50 to 200 houses, and they are citizens’ primary point of contact. So working with them is an advantage as they are well known and trusted by the community

What is Next?

Seeing the positive outcomes on the two pilot subwards, there is a need to extend the project to the remaining six subwards of Tabata and even to the whole city if we had the support and funding from different partners. Joshemi Company that we’re working with are also eagerly waiting for the extension to the remaining subwards as they understand the power of data now- they even decided to pay community leaders and wajumbe that were helping mappers on data collection. 

If this process is replicated in the remaining wards of the city, trash collection will be easier, the city will be clean and may also reduce the intensity of flooding as it is normally caused by blocked drains and rivers. There is also a need to develop an integrated solid management system which is cost-effective and that takes into account economic options for solid waste management like recycling. The community and the general public also need to take responsibility for the process by collaborating with waste collection companies because the benefits are reciprocal. Our mappers are working on solidifying relationships between clients and companies as there was observed drift among them.

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