Every day, diarrhea diseases from easily preventable causes claim the lives of approximately 5 000 people, most of them young children. Sufficient and better quality drinking water and basic sanitation can cut this toll dramatically, and simple, low-cost household water treatment has the potential to save further lives. As we enter the International Decade for Action Water for Life 2005 - 2015, this report makes clear that achieving the target of the Millennium Development Goals (MDGs) for access to safe drinking water and basic sanitation will bring a payback worth many times the investment involved. It will also bring health, dignity, and transformed lives to many millions of the world s poorest people. The humanitarian case for action is blindingly apparent. The economic case is just as strong. Improved water and sanitation will speed the achievement of all eight MDGs, helping to: eradicate extreme poverty and hunger; achieve universal primary education; promote gender equality and empower women; reduce child mortality; improve maternal health; combat HIV/AIDS, malaria and other diseases; ensure environmental sustainability; and develop a global partnership for development. At US$11.3 billion a year, the dollar costs of achieving the MDG drinking water and sanitation target are affordable; the human costs of failing to do so are not. The International Decade for Action Water for Life provides the incentive for coordinated efforts to prevent the daily disaster of unnecessary deaths and develop a global partnership for development.