·         We review general adaptation cost estimates for the continent and the main economic appraisal methods, before then describing 13 previous adaptation appraisals for the African water sector

·         We conclude that this list of 13 is very sparse and that many gaps still remain for further work on this topic – yet few advancements have occurred since 2010

·         Key challenges to better appraisal estimates include: (1) the need for greater focus on the non-infrastructural, ‘soft’ costs of potential adaptation responses and (2) the need for appraisal methods that adequately capture the cascade of climatic and socio-economic uncertainties and assumptions that underlie the planning of context-specific adaptation responses