This article aims to contribute to discussions on the management of water resources and the elements associated to water security. The discussion has focused on two main aspects, first, in the theoretical frame about discussions of water security and second, in the presentation of the elements which composes the current scenario of water management in the Metropolitan Region of Rio de Janeiro (RMRJ), based in the discussions about the centrality for Rio de Janeiro's water supply focused in Paraíba do Sul river, and in the role of agencies and organisms associated to water management in this territory. Based in the researching about the water availability and quality in Rio de Janeiro and the mechanisms presents in this State, the elements presented in this article demonstrated a context of water insecurity in RMRJ.