From an article titled "Water policy 'fails world's poor'" by Mark Kinver on BBC News:

Almost 20% of the world's population still lacks access to safe drinking water because of failed policies, an influential report has concluded.

The UN World Water Development Report also blames a lack of resources and environmental changes for the problem.

The study calls for better leadership if a goal of halving the proportion of people without proper access to safe water by 2015 is to be achieved.