In this paper we present six scenarios about the possible evolution of the water supply and sanitation sector in Europe, considering both liberalised and non-liberalised environments. The scenarios were developed around three macro-storylines, namely (1) pressure for more competition and private sector participation; (2) opposition to liberalisation and pressure to return to direct public or community management; and (3) maintenance of the status quo. We then define the institutional framework of each scenario taking into account the specificities of the sector. The institutional framework aims at illustrating the relative positioning and changing power attributes of the main actor groups. We conclude this institutional analysis of the scenarios by assessing their viability based on three criteria, in particular stability, efficiency and accountability.