Water is a key prerequisite for human and economic development, and for maintaining ecosystems. However, billions of people lack access to water and sanitation services, mainly due to poor governance and inadequate investment and maintenance. This report, which emphasises the economic and financial aspects of water resources management and water service provision, the need for an integrated approach (including governance considerations) to address these complex policy challenges, and the importance of establishing a firm evidence base to support policy development and implementation, summarises the results of OECD work in this area.