Notes : "Safe drinking water is one of the most basic human requirements and one of the Millennium Development Goals (MDGs) by 2015 is to reduce by half the proportion of people unable to reach or afford safe drinking water. As a result, estimates of access to safe drinking water are a cornerstone of most international assessments of progress, or lack thereof, toward solving global and regional water problems." (PWI).
Source: Pacifica Water Institute. The World's Water 2006-2007 Tables.