The Water Problem is a worldwide crucial policy issue for local and national governments. As several international experiences have largely testified, water's strategic role in economic and social development as well as freshwater shortfalls in many regions of the globe ask for a quick re-thinking of managerial practices and models. In this essay, we argue that water's mixed nature of private/economic and social/public
good suggests a mixed managerial model for water services implemented through different forms of public-private partnership (PPP). Therefore, by using insights from economic literature on privatisation, we propose some applied criteria which can drive governments in designing and architecting PPP for water services provision taking into account efficiency, equity and sustainability requirements.