**6. Sanitation in the urban ecosystem**

All relevant urban sanitation stakeholders should be consulted in the planning process, such as water and sewerage utilities, the private service providers and the end‐users. This helps the understanding of the heterogeneous urban environment and gives access to first‐hand information from different perspectives. Depending on the stakeholder, data can be collected through different tools, such as household surveys and expert interviews, as well as other participatory methods that are focus group discussions, town hall meetings, transect walks or

New technologies facilitate data collection and visualisation. Mobile data collection and geo‐ referencing tools quicken the process, increase the quality of the data collected and allow rapid visualisation of complex urban areas. Mobile data collection is gaining importance as data can be collected with any mobile phone and viewed in real time [36]. With the decreasing costs and complexity of geospatial data collected from satellites, these data become accessible not only to all urban planners but also to civil society, which can even participate in the monitoring

An innovative way to visualise outcomes and communicate the urban sanitation challenge at the city‐wide level are the so‐called 'shit/excreta flow diagrams' (SFDs), which clearly show how excreta is or is not contained as it moves along multiple pathways from defecation to disposal or end‐user. As illustrated in **Figure 2** for the city of Dar es Salaam, Tanzania, the SFD

**Figure 2.** The excreta flow diagram for Dar Es Salaam, Tanzania, shows the proportion of faecal matter that is safely

managed (in green) compared to unsafely managed streams (in red) [37].

efforts. This is often already done, for instance, with the monitoring of water points.

participatory mapping [5, 9].

128 Sustainable Urbanization

Integrating sanitation in the urban ecosystem, that is seeing it as more than merely collecting and treating wastewater, is seen as a main driver or incentive for more efficient and sustainable sanitation services. This can take different forms: (i) synergies between different services (e.g. energy, communication); (ii) multi‐functional sanitation concepts; (iii) urban valorisation of sanitation end products (e.g. treated wastewater, nutrients, heat or biogas).

Good city sanitation plans recognise the links between sanitation and other municipal services [5]. For example, uncollected solid waste ends up in drains and sewers, greatly increasing maintenance requirements. Consideration of the integration between these different services is important to ensure effective sanitation service delivery. Storm water drainage also needs to be planned in parallel, as neglecting it can quickly lead to the collapse of the sanitation system, especially combined with the lack of solid waste management.

A utility which manages different urban services may be more sustainable if one of these public services is lucrative. For example, in Cuenca, Ecuador, the utility manages water, sanitation and communication. In that case, the communication sector contributed to the development of inclusive and state‐of‐the art sanitation services, through cross‐financing. This would not have been possible if both services were managed separately. Managing several services at the same time can also support the often delicate issue of fee collection. For example, collecting sanitation fees together with the electricity bill can significantly increase the collection rate, and thus the cost recovery.

Similarly, multi‐functional sanitation concepts increase the sustainability of the sanitation component through the provision of other services. Multi‐functional public toilet concepts in low‐income settlements have made their proof, like the Ikotoilet in Kenya, which brings together toilets, showers, sale of personal care products and, in collaboration with local companies, supports advertising, telephony, and shoe‐polishing services as well as sales of snacks, drinks and newspapers. In general, linking productive assets with sanitation services increases sustainability. Activities needing biogas, such as communal kitchens, can for instance be built in synergy with sanitation infrastructure in green markets; similarly, decentralised treatment plants can be built so that the treated effluent can directly be used by urban farmers for irrigation. Linked with solid waste management and landscaping, multi‐functional sanitation concepts can also contribute to increase the recreational value of a neighbourhood.

The valorisation of sanitation end products should be fostered. In high-income countries, grey water recycling in buildings, on‐site reuse of treated wastewater for urban gardening and heat recovery from sewage are increasingly being implemented, as well as the biogas production in centralised treatment plants for electricity production or as a fuel for public transportation. Technological advances, increasing scarcity of water and rising prices of fuel and fertilisers will soon make such techniques more affordable and competitive in low‐ and middle‐income areas as well.
