As "market referees", regulators contribute to the delivery of essential public utilities. Their organisational culture, behaviour, actions and governance are important factors in how they, and the sectors they oversee, perform. The OECD Performance Assessment Framework for Economic Regulators (PAFER) looks at the institutions, processes and practices that can create an organisational culture of performance and results. This report uses PAFER to assess both the internal and external governance of Brazil's National Agency for Water and Basic Sanitation (ANA). The review offers recommendations for the regulator to build upon its strong technical reputation and good practices. It proposes an integrated set of recommendations to help ANA best fulfil its roles relating to water resource management and water-use regulation, dam safety, and water supply and sanitation.