112 The Future of Water in African Cities
Notes 1. For a detailed description of all scenarios see Eckart et al., 2012. 2. Assumptions of the study are as follows: Nairobi has two dry periods of three months each. Three-month water supply storage provides for the three dry months. The assumption is that stormwater collection would provide sufficient water throughout the year. For the detailed dimensioning of the storage reservoir, the real rainfall pattern would be used for the different locations of the clusters, as the rainfall in Nairobi varies significantly with location. 3. This will be caused by limits to infrastructure and resources. The capacity of the infrastructure needs upgrading in the near future (Eckart et al., 2012a). Even then the potential of the existing resources cannot meet future demand, especially during the dry season. 4. Greywater and blackwater recycling are sanitation options that also contribute to the water resources. In the peri-urban areas onsite sanitation systems such as ecosan and composting toilets have been proposed (see Eckart et al., 2012a). 5. Detailed information about population density, water consumption, and costs of implementation (represented in net annual costs) in the remaining clusters are provided in Eckart et al. (2012a), section 4.4. 6. Information for this section has been drawn from a desk study (Biedler, 2012).