In the aspiration to upscale their activities in the global South, development aid agencies have a tendency to design and implement generic models. These are often associated with desired characteristics and principles, such as participation or inclusion of the poorest. However, in the dynamic environment in which models are implemented, the design characteristics and principles are mitigated, adapted or reinforced by context-specific socially embedded institutions through a process of bricolage. This process is driven and shaped by power relations and, as a consequence, development interventions tend to reproduce local power structures, and benefits derived from the projects are likely to be captured by elites to the detriment of others. Models thus carry the danger of reproducing and even increasing existing inequalities. Similarly, initial claims of participation or inclusion of the poorest often fail to materialize. We develop these arguments by focusing on the Water Users Association model in Lilongwe, Malawi.