Urban water services represent a cornerstone of human civilization. They are fundamental for the wellbeing of the people living in an area and the economic growth in the region. Given their monopolistic nature, and the increasing expectations placed on the quality, sustainability and affordability of those services, their regulation is necessary to meet the expectations of the citizens of the 21st century. Regulation of Urban Water Services provides an overview of the regulation of such services around the world and in Spain. A series of case studies presented by international experts, aiming to identify best practices in regulation especially useful in those parts of the world where the regulatory model has not been fully designed or implemented. The reader will conclude that in order to provide water services meeting high quality standards, to face the growing complexity of the social and environmental constraints and to guarantee that those services will be economically, socially and environmentally sustainable; an effective form of regulation is necessary.