Shortages of human resources in the Water, Sanitation and Hygiene (WASH) sector will undermine the progress made by many countries over the last decades to increase access to water and sanitation. In this report, the first of its kind, the IWA provides an overarching recommendation for the development of national capacity development strategies that have high-level political buy-in with involvement from multiple actors to ensure sustained, adequate professional and technical capacity. The report also calls for concerted action at regional and global level to collect relevant human resources data, and perform further research to strengthen the evidence base on which action plans and strategies can be built.