Water and sanitation is a key sector where much effort is needed: with over a billion people without access to drinking water and 2.6 billion lacking basic sanitation, developing the relevant infrastructure constitutes a major challenge. Financing the achievement of the Millennium Development Goal (MDG) targets for water and sanitation in developing countries (i.e. halving the proportion of people without access to drinking water and sanitation by 2015) would require investments of some USD 72 billion per year (18 billion for coverage extension and 54 billion for maintenance). OECD countries also face significant financial challenges to replace ageing water infrastructure and comply with ever-stringent water regulations: France and the UK for instance need to increase spending on water by 20% and Japan and Korea by over 40% to 2030 to maintain current services. To meet these tremendous needs and expand their infrastructure in a context of tight budgetary constraints, but also in an attempt to improve the efficiency of – often deficient – water systems, many developing and emerging countries have sought the involvement of the private sector.