Abstract
It is well known that water supply and sanitation remain grossly deficient in low-income districts of cities throughout sub-Saharan Africa, with likely severe negative impacts on health. Most low-income communities depend on non-networked (on-site) sanitation; few African cities have an extensive sewerage system, but nonetheless city-wide sewerage is widely seen as the long-term aim by municipal planners. In recent years, some sanitation specialists have argued that low-cost sewerage can be an appropriate solution for African cities; others that sewerage is inappropriate, because of its high financial cost, requirement for well-resourced local governance, and purportedly negative environmental impacts. Against this backdrop, this thesis sets out to assess whether sewerage can be an appropriate solution for African cities, and if so in what circumstances. An expert opinion survey early in the research indicated that most sanitation specialists consider sewerage to be an appropriate solution in some situations. A meta-analysis of existing health impact studies confirmed that sewerage interventions typically have a substantial positive impact on health. A detailed outcome evaluation of the PAQPUD settled sewerage project in Dakar (Senegal) was performed, and this work was supported by shorter evaluations of sewerage pro-poorness in Accra (Ghana) and Nairobi (Kenya), and by a review of outcome evaluations of previous sewerage projects in African cities. This research concludes that sewerage can certainly be an appropriate solution for high-density low-income districts of African cities; the key requirement is that governance standards and institutional capacity be sufficient to ensure effective planning, implementation and long-term management of a networked sewerage system. Common "environmental" arguments against sewerage (including that it will substantially increase domestic water use) are judged to be over-stated. Capital cost will invariably be higher than for non-networked systems: but in certain habitat types, sewerage may be the only solution that prevents disease. It is difficult to generate geographically generalisable estimates of the lifecycle costs of sewerage, and impossible to achieve generalisable cost-benefit relations: so comparative cost assessments need to be done in specific contexts. The thesis offers recommendations for effective planning and implementation of sewerage programmes serving low-income districts of African cities, stressing the importance of approaches ensuring high connection rates and genuine propoor targeting.