The National Rural Water and Sanitation Project was implemented in Brazil in the 1980s. It did not succeed because it did not become an institutionalized public policy that reached the entire national territory, and it was discontinued a few years later. This article assesses the factors explaining this failure using the 5C Protocol. The results show that the flaws in the implementation impaired the sustainability of the established systems. Political reasons compromised the principles idealized during the conception of the project. Also, technical and institutional limitations constrained the implementation of the recommended innovations, such as social participation, and adaptive technologies.