World Toilet Day, 2018

By Micheala Chan


Today (Monday 19 November) is World Toilet Day!


World Toilet Day was established by the World Toilet Organization in 2001 and declared an official UN day in 2013 by the UN General Assembly.


This day aims to address Sustainable Development Goal (SDG) 6: to ensure availability and sustainable management of water and sanitation for all by 2030. At the rate we are working, we are far behind where we need to be to ensure this achievement. Currently, around the world, 4.5 billion people are still without safely managed sanitation and 892 million people still practise open defecation [1].


Exposure to human faeces and the lack of toilets means that problems in public health, living conditions, education and economic productivity still persist. Waterborne diarrhoeal diseases are still responsible for 2 million deaths annually [2] and cholera is still a major problem in many developing countries. A lack of toilets and handwashing facilities also has a large impact on girls’ access to education, with many dropping out of school when they start menstruating.


Working in Vingunguti, an informal settlement in the Mjimpya ward of Dar es Salaam, Tanzania, this is a mission CDI’s WaSH Project has become highly aware of and also wholly dedicated to. 70% of the city’s residents live in informal settlements like Vingunguti [3] and 97% of them are users of pit latrines, with only 6% connected to the modern sewerage system [4].


To date, CDI has constructed 54 accessible toilets connected to the sewerage network, serving an estimated 375 people, since 2014. The latrines have been funded either by the community themselves or by DAWASA (Dar es Salaam Water and Sanitation Authority). The construction has been facilitated by local technicians and workers, and designed mainly by the KITE Dar es Salaam team, giving Tanzanian students the opportunity to apply practically the knowledge learned in university. Further, these toilets have enabled women in the community to take on a leading role, for example, as household representatives and Chairpeople of the Sanitation Users Authorities (see for more information).

Toilet 1

To date, CDI has constructed 54 accessible toilets connected to the sewerage network, serving an estimated 375 people, since 2014.

When Nature calls, CDI answers.


[1] WHO/UNICEF (2017):

[2] WHO.

[3] Jenkins, M. W. (2015). Pit Latrine Emptying Behaviour and Demand for Sanitation Services in Dar es Salaam, Tanzania. International Journal of Environmental Research and Public Health. 12(3), pp. 2588-2611

[4] Chaggu, E. et al (2002) . Excreta Disposal in Dar es Salaam. Environmental Management. Nov 30 (5), pp. 609-620


A Day in the Life of a WaSH Biogas Volunteer

My name is Sam Watson and I am working with the Biogas Team on the Water, Sanitation and Hygiene (WaSH) Project.

After hearing about CDI through a lecturer in my university department, I joined CDI because I saw the WaSH Project as an opportunity to implement skills from my Chemical Engineering degree whilst making a difference in communities facing poverty and poor health.

I work closely with two other volunteers on the Biogas Team named Amon and Micheala.

7:20am. The alarm goes off. I usually hate early starts, but not today because I’m going to ‘site’.  The place commonly referred to by CDI volunteers as ‘site’ is the location of the WaSH Project’s latest brainchild – the biodigester. This device is effectively a huge rubber bag lying in a long, deep trench.  Sewage from one of the WaSH Project’s simplified sewerage networks flows into this bag and is turned into biogas which can be burned for cooking or heating.

7:50am. The heavy rain has stopped just in time for me to go to the canteen. I get to breakfast nice and early but the canteen hasn’t started serving food… This is only a minor inconvenience to what I’m anticipating will be a significant day.

Figure 1

Breakfast table accompaniment

8:45am. I am catching a bus to the site.

The key idea behind the biogas project is a business model in which biodigester technology can be used to add value to the sewage by converting it into biogas fuel. This fuel can then be sold to members of the local community. Profits generated from biogas sales can then be used to pay back the costs of the biodigester and sewage network.

Today we hope to do an experiment which should help us to determine whether selling biogas is profitable. It involves measuring the amount of gas produced by the digester in a given time. This will allow us to estimate our operating profit.

9:45am. We stop off at the hardware store to buy two pairs of rubber gloves.

Figure 2

Amon and Micheala at the hardware store

9:50am. Only moments after leaving the hardware store, I hear someone shouting, “I love you!” I turn to see that it is us who are being addressed, by a woman leaning from a window.

10:06am. We arrive at site. We connect our measuring device to the digester but measure no gas coming out.

Figure 3

The measuring device (known as a flowmeter) with the digester in the background, to which it is connected

After over an hour of trying things, the digester has become completely deflated, showing that there is no longer any gas in the digester. The attempt was not successful, so we decide to leave.

Figure 4

The flexigester, deflated to the level of the water (i.e. it has no gas in it!)


11:30am. Shortly before leaving, the team discover a mysterious locked chamber next to the digester. After a long while of trying to smash the lock with a bolt, we hire some local technicians who easily break open the lock. The chamber is empty.


Figure 5

Amon attempts to break open the chamber by smashing the rusted padlock


12:45pm. A long commute and we’re back at base. Time for a quick debrief with one of my PDs before lunch.

1:00pm. At lunch, a member of the WaSH team tells us which Mean Girls characters each of us are.

2:00pm. Back to work. This afternoon is an ideal time to work on my ‘day in the life’ blog.

4:00pm. Time for an exciting meeting with the WaSH PDs about the future strategy and direction of the Biogas Project. We discussed the latest findings and calculations in relation to the biogas business model.

5:00pm. Work is over but my roommate has gone to Vingunguti with the only key to the room and won’t be back for a while. However, I can’t complain as it’s my fault.

Tonight is the Kite DSM fundraising dinner and I’m scheduled to play with a band. I go to help the other band members load the taxi with our kit.

5:30pm. People are starting to leave for the fundraising dinner (which starts at 6:00pm) but my roommate still isn’t back. Luckily, I have a great book in my bag to keep me occupied in the meantime.

6:30pm. My roommate has arrived back and we can now go into our room to start getting ready for the dinner.

7:30pm. I arrive at the dinner with my roommate and next-door neighbour in time for a speech by Kite DSM by Director David Leonce.

8:30pm. It’s time for the band to perform. The ‘Cambridge Groove Initiative’ played three songs, including the classics ‘Signed, Sealed, Delivered’ and ‘Summertime’.

Figure 6

The ‘Cambridge Groove Initiative’


11:30pm. I’m on my way back to the accommodation. It’s been a long day and I’m ready to go to bed.


WaSH Spotlight: Residents

One of the most important aspects of a successful project is the positive and lasting impacts it has on the local community. As part of the WaSH project Spotlights series, we have explored the different sub-teams within the overall project and their place in the model. However, it is time to focus on the residents, who are the most important part of the project.

Residents in Vingunguti choose to opt in to the community simplified sewerage network, following educational discussions explaining the health and environmental benefits of the system. The latrines are a household investment, organised through a deferred payment scheme. As a result, residents own their latrines and are more likely to be committed to contributing to maintenance and community decision-making.

Our community engagement team has spoken to some of the SUA members  of Routes 4, 5 and 6 (for more information, check out ). The issues they face have been highlighted below with quotes from the community.


The Septic Tank

“I am very regretful to those who haven’t joined the network until now as they will keep facing not only health problems but also the difficulties in emptying their septic tanks when full as the area is unplanned settlement and there is no access roads for the trucks needed to empty the septic tanks when full”

  • Member of Route 4 SUA


Before the latrines were introduced in Vingunguti, most houses relied on septic tanks, which had to be emptied regularly. In Dar Es Salaam 80% of households are dependent on pit latrines, whilst only 6% are connected to a sewerage system.[1] Pit latrines collect and store human faeces in a pit direct below a toilet. The pit should be periodically emptied. However, due to cost, most households do not responsibly empty their pits and instead allow them to overflow during the rainy season. Uncovered faecal matter can increase the incidence of trachoma and most waterborne diseases.[2] Simplified sewerage is an affordable, safer alternative.

The septic tank is a tank, typically underground, in which sewage is collected and allowed to decompose through bacterial activity before draining by means of a soakaway. A soakaway is a pit into which waste water is piped so that it drains slowly out into the surrounding soil.

Although there are many benefits of the septic tank system, the residents of Vingunguti have found that the simplified sewerage system is “not only cost friendly but also space saving and environmental friendly.” The convenience of having a system which does not have to be regularly emptied and which also has the capacity to handle larger amounts of sewage makes the CDI and Kite WaSH model very suitable for use in crowded, informal settlements such as Vingunguti.


Reducing Disease

“Currently the situation is very impressing as there is no diseases such as Typhoid that used to occur. We are really thankful because this project has not only helped to reduce waterborne diseases but also has promoted hygiene”

  • Member of Route 4 SUA

The number of people involved in the project so far is only about 400 people, and detailed data from health centres is difficult to obtain due to confidentiality so a thorough investigation into the occurrence of water-borne diseases has not been done. Research from the WHO states that the “safe human excreta disposal brings about huge health benefits”[3]. It is reasonable to extrapolate that the occurrence of diseases in Vingunguti has decreased if the simplified sewerage network is working. Comments made by members of the SUAs has confirmed this fact anecdotally.

[1] Chaggu, Esnati, et al. “Excreta disposal in Dar-es-Salaam.” Environmental Management 30.5 (2002): 0609-0620

[2] Montgomery, Maggie A., and Menachem Elimelech. “Water and sanitation in developing countries: including health in the equation.” (2007): 17-24


WaSH Spotlight: Biogas

Key vocabulary & definitions:

Biodigester: a device or structure in which the digestion of organic waste matter by bacteria takes place with the production of a burnable biogas and a nutrient-rich slurry.

Biogas: gaseous fuel, especially methane, produced by the fermentation of organic matter. Biogas is particularly good as it is a renewable, clean energy source (both in terms of health and environmental impacts), reducing the greenhouse effect and is also capable of producing organic NPK-rich fertiliser as a byproduct of the production process.

Simplified sewerage: sewerage system with conscious efforts made to eliminate unnecessarily conservative design features such as using smaller diameter pipes (see for more information)

The team:

Image from iOS (1)

The biogas team this year is made up of three volunteers; one from Kite DSM and two from CDI. Amon Gracephord is a Kite DSM volunteer; he is a 3rd year student studying Municipal and Industrial Services Engineering. The two CDI volunteers (Micheala Chan and Sam Watson) are both in 3rd year and study Civil & Structural Engineering and Chemical Engineering respectively.


The Flexigester

Image from iOS

In 2015, CDI formed a partnership with SOWTech, a Cambridge-based company working on innovative solutions in the field of sanitation and waste management. In August 2015, a V40 biodigester (with a volume of 40 m3) was purchased from SOWTech and was installed in Vingunguti at the outflow of Route 4. It is made of butyl rubber, a flexible material, which allows it to stretch slightly with gas production.

The site lies next to the Spenco Waste Stabilisation Ponds. These ponds are large, man-made water bodies into which household and industrial waste flows. These ponds are used for the treatment of wastewater around the world and are especially appropriate for rural communities.


How does this fit in with the rest of WaSH?

The biodigester is an important part of the business model proposed by CDI. By creating a business model based around simplified sewerage and the biogas generator, the potential for the propagation of sanitation solutions is incentivised for businesses and is driven by the economy, rather than government funding.

In this model, a biodigester is installed at the end of a simplified sewerage network. The sewage from the network flows into the bio-digester, which digests the material and produces biogas. The plan is to sell this biogas as a sustainable, clean energy source to members of the local community. The funds generated are intended to recuperate the original investment, although this is expected to take a few years of continuous biogas production. The funds will also provide future funding for scaling the simplified sewerage networks.

The biodigester facilitates the expansion of simplified sewerage, not just financially, but also geographically. By fully digesting the sewage, the biodigester could make simplified sewerage applicable in areas with no sewage treatment ponds.


The plan for this year:


The decision had been made in the last year to decommission the Flexigester as it was found that the unique environmental and weather conditions in Vingunguti made this particular model of digestor unsuitable for constant biogas production. The team will be carrying out this decommissioning in the next few weeks. A decommissioning report is being compiled to analyse lessons learned and how best to move forward with biogas in the future. This will be done in collaboration with the WaSH Monitoring & Evaluation team, who will advise on how to make the long-term vision achievable.


The New Digester

The biogas team has been in discussions regarding a new biodigester to install once decommissioning is finished. Although the decision has ultimately been made not to install this year (so that the business model can be thoroughly examined first), the team is taking steps to ensure the smoothest transition into the next biogas team, so that they can get into installation and testing as quickly as possible next summer. These steps involve checking the technical proposal suggested by the supplier and negotiating a maintenance contract, which is important as the aim is for the biodigester to be a reliable year-round source of biogas while CDI and Kite only operate on site during the summer.


The biogas team will be working on grant applications towards the end of this summer in order to raise funds for the future installation of digesters. This is a crucial activity, and it is important to ensure that fundraising is a continual year-round exercise, to ensure the sustainability and long-term success of the WaSH Project.


The biogas team will be taking a look at the direction in which the biogas project is headed and discussing future plans and how it fits into the WaSH project model. In this area, the team will be looking into the business plan and filling in gaps by speaking to suppliers and experts, both of biodigesters and biogas stoves, amongst other things. A survey will also be undertaken in an analogous community to Vingunguti to gauge community interest and parameters for the financial modelling and business model.


The biogas team will be working to ensure smooth handover with as little loss of knowledge as possible. This will enable teams to make informed decisions based on actions previously carried out, knowing the context of historic decisions.

The future:

In the future, it is hoped that a successful pilot of the biodigester-simplified sewerage model can be carried out. This will rely on the correct installation of a biodigester at the end of Route 4. Once gas has been continuously produced and profitability and technical feasibility have been proven, the plan is that a channel for local entrepreneurs to roll out their own simplified sewerage networks and biodigesters can be created to spread the CDI model of sustainable, scalable, community-led solutions to sanitation.

WaSH Spotlight: Community Engagement

Key vocabulary & definitions:

WaSH Water, Sanitation and Hygiene.

Sanitation Users Association (SUA) – a committee consisting of one representative from each household that deals with problems that arise on the network.

Simplified sewerage network – The network of pipes connecting member’s latrines to the sewage ponds.


The team:

The community engagement team consist of four volunteers: two from KITE DSM and the other two from CDI. At university, the team specialises in a diverse range of subjects, studying: Environmental Engineering, Community Development, Biological Anthropology and Politics and International Relations. The mix of different subjects makes for a well-rounded team with exciting new ideas.


What is community engagement?

Community engagement is the framework that allows members of the community to become involved and empowered in their development. This is achieved through consultation of community members when making key decisions and taking their feedback on our project seriously. For example, this summer began with consultations with the chairpeople of each network and focus groups and surveys of network members. Through this, we identified a number of ways to improve the SUA model to make it align more closely with how the community functions.

Community engagement works closely with the other WaSH sub-teams, for example:

  • Working with the network team in ensuring that any infrastructure built is appropriate and specific to the community.
  • Organising workshops to run in the community which help promote the accompanying behavioural change.
  • The team also has close links with Monitoring and Evaluation; evaluating the effectiveness of past aspects of the project and applying what we’ve learnt to new initiatives.  


The plan for this year:

The WaSH project provides new users with a deferred payment scheme; this allows people joining the system to pay back the latrine construction costs over a period of up to four years. This prevents the up-front cost of a new latrine being a barrier to anyone who wishes to connect to the network. Community engagement oversees the contracts for the deferred payment scheme. It is important that new users joining the network this summer to ensure the contracts and their financial implications are fully understood. To achieve this, the language and structure of the contracts are being adapted to make them more accessible. The team will then have sessions in each household explaining the contracts to the new users. Parallel to this the team will be organising training sessions on SUA functions to allow the new users to easily integrate into the existing SUAs.  

An important part of the WaSH project is the existing education initiatives such as the WaSH entrepreneurship workshops. Currently new network members are invited to 18 workshops run over the space of nine months by a local NGO: Bridge for Change (BfC). The content of the workshops was decided in consultation with community members and cover topics like latrine management, sanitation and hygiene and life skills. This summer, the community engagement team will be working with BfC to continue improving the workshops, focusing on increasing attendance and ensuring the content remains engaging, accessible and relevant. The team will also be involved in BfC’s plans to expand their workshops beyond Vingunguti.  


In the future:

Sustainability is a core principle of CDI and good community engagement is key to achieving that. To ensure the long-term sustainability of the WaSH project, the community needs to take ownership of their simplified sewerage network, with the goal of the networks running autonomously in the future. At the end of summer, the team will be running a ‘celebration day’ inviting new members of the networks, DAWASA, other NGOs and press. The purpose of this event is to promote the project and instil a sense of pride and ownership of the network in community residents. The improved community engagement framework and SUA structure developed this summer will be necessary for achieving the goal of year-round building of new simplified sewerage networks.

WaSH Spotlight: Monitoring and Evaluation (M&E)

Key vocabulary & definitions:

M&E: Monitoring and Evaluation

SUA: Sanitation Users Associations – a committee with one representative from each household that deals with problems which arise on the simplified sewerage network

Latrine: A toilet

The team:

The monitoring and evaluation team is this year made up of two volunteers; one from Kite DSM and one from CDI. Reuben Chacha is a Kite DSM volunteer, he is a 3rd-year student studying Municipal and Industrial Services Engineering. Bahumi Motlhanka, the CDI volunteer, is a 3rd-year Chemical Engineering student. The M&E structures within CDI and Kite DSM are regularly reviewed, last year an M&E officer was included on the CDI central committee and this year a KITE DSM M&E officer has been added to the Kite DSM committee. The M&E teams across all projects run by CDI and Kite DSM, are now representative of both organisations.


Theory of Change:

The Theory of Change is a planning tool used by the M&E team to direct the work this summer. It is a comprehensive description and illustration of how and why the desired change is expected to happen in a particular context. The vision of the WaSH project is to provide simplified sewerage solutions for residents of informal settlements to avoid the transmission of diseases associated with unsuitable sanitation conditions.

The Theory of Change is constructed backwards after identifying the overarching goal: for the WaSH project, this is to solve the problem of sanitation in Vingunguti. It then maps out the necessary preconditions to achieve this goal, such as making sure that the residents in Vingunguti are engaged with the conversions of their pit latrines to the simplified sewerage system. The plan includes intermediate outcomes and activities relevant to all sub-teams within the WaSH project. One of the project’s intermediate outcomes is to create awareness of the importance of converting to the simplified sewerage system, this is achieved by providing training to the community on the importance of the system in relation to their general hygiene and wellbeing. To make sure that the plan is adaptable and relevant, the assumptions around which the theory is constructed have been considered, such as assuming that the residents in Vingunguti would be able to afford to adapt their latrines to join the simplified sewerage system. In practice, the theory of change shall be adapted as evidence gathered from the community either confirms or dispels the assumptions that were made initially. An example of the assumptions that are continuously reviewed is that of the affordability of the deferred payment structure. The M&E and Community Engagement teams interview residents and gather information about repayment rates and adapt the payment structure to suit the community.

The M&E team has made sure that the entire WaSH team is aware of the form of the Theory of Change so that each team can see how they fit into the ‘bigger picture’, as well as how the teams can collaborate to execute the project effectively.


Example of a theory of change diagram – they are not normally this pretty!


Previous WaSH M&E teams have monitored community satisfaction with the simplified sewerage network because the project can only be described as successful if it is perceived as such by the residents of Vingunguti. This work has been carried out using questionnaires, focus groups and interviews, working with the community-led SUAs to coordinate the efforts.

The plan for this year:

This year the M&E team plan on building on the work carried out by the past M&E teams by continuing to engage the community on issues around the simplified sewerage network. This will hopefully allow the pilot project to keep improving to better suit the community’s needs. We plan on using questionnaires, focus groups and interviews as appropriate, to gather information about hygiene practices, perceptions of the simplified sewerage network as well as challenges facing the residents from a sanitation perspective. These methodologies are designed with the Theory of Change in mind to realise the objectives, test the assumptions made and inform the current and future activities of the WaSH project teams.

The team plans on engaging with the residents in Vingunguti who are about to connect to the simplified sewerage network this summer, which will provide a clearer picture of the lives of the residents before and after being connected to the network. This will be done using questionnaires to determine certain health and hygiene markers and see whether there are improvements in these areas after being connected to the simplified sewerage network. This was an area of data collection identified by this year’s M&E team as requiring improvement.

In addition to the work that the M&E team will be doing this year, the team will be expanding its work to include developing the framework around the biodigester to better inform future strategic decisions around biogas. This is a new area for the M&E team and they are hard at work doing research into current industry standards and are trying to find the best way to make adaptations to the framework within which the biogas project is run.

The future:

The M&E carried out in the future will allow the WaSH Team to gauge the community engagement in the WaSH project. By gathering information on community attitudes and aspirations for the WaSH project, the M&E team hopes to inform the direction of the project going forwards so as to facilitate the full transition of the project into the community’s hands.


WaSH Spotlight: Network Construction

Key vocabulary & definitions:

DAWASA: Dar es Salaam Water and Sanitation Authority

Connection box: connects between a latrine and the network

Junction box: connects pipes in the route

Latrine: a toilet



The team:

The network team comprises 5 members, all volunteers of Kite DSM: 4 final year students (all studying Environmental Engineering) and a second year student, studying Water Resources and Irrigation Engineering.

This is the first year there have been no UK volunteers working on the simplified sewerage network team: this area of the project is being handed over completely to the Tanzanian team.


The location:

Vingunguti is an administrative ward in the Ilala district of Dar es Salaam, Tanzania. According to a 2012 census, the population of Vingunguti is 106,946. Nearly all the settlements in Vingunguti are informal and the area is largely dependent on pit latrines. CDI works in an area close to the Spenco waste settlement ponds.

These waste settlement ponds are the exit points for the sewage from our simplified sewerage routes. Waste from industry and households throughout the city is also treated here.


The concept: Simplified Sewerage

Simplified sewerage is a widely used sanitation technology throughout Pakistan and Brazil. It is based on the idea that conventional sewerage systems are overly conservative in many of their design features, and therefore unnecessarily expensive and technically complex. Traditional sewerage systems haven’t been able to keep up with the phenomenal rate at which informal settlements like Vingunguti are growing, and would be impossible to retrospectively install around the unplanned housing layout. Simplified sewerage uses smaller diameter pipes than conventional sewerage systems. These pipes are placed at shallower depths, reducing the required excavation volume as well as the cost and complexity of repairs.



In previous years, a new simplified sewerage route was constructed every summer. The first route was built in 2014. CDI have facilitated the construction of a further three routes.


The plan for this year:

The network construction team’s aims for this summer are to facilitate the construction of a further ten latrines and to connect them into existing network routes from previous years, in order to continue satisfying demand from the community. Beyond the summer, the team plans to continue facilitating the construction and connection of more latrines into the pre-existing network routes.

So far, surveys have been conducted to identify the number of houses which will be joined to the network, the number of people served and the technical complexity of each connection to the existing route. The team will carry out design work of the new connections, supervise construction (which will be contracted out to local technicians) and conduct maintenance due to operational failures.

The team is also in charge of collating documents for a proposal to DAWASA. A large part of this is preparing a budget estimate to submit to DAWASA for funding. At the end of the summer, when the latrines are finished, the total actual spending will be calculated and DAWASA reimbursed for any initial overestimation. However, the application to DAWASA is to fund the central network pipes and junction boxes only – the cost of the latrine construction will be paid back by the households in the route. This financing model will be explored further in the Spotlight on Community Engagement.


The future:

The goal is for an “alumni team” to be formed from up to four graduates of the network team and one graduate from the community engagement team. The importance of the alumni team lies in the rapidity of expansion: at the moment, network expansion happens at about 10 to 15 new connections each year, as the team only works for 2 months during the summer. However, a dedicated year-round network team will enable the rate of expansion to increase significantly, allowing more community members to gain access to safe and affordable sanitation in the near future.