The UN suggests that each person needs 20-50 litres of water a day to ensure their basic needs for drinking, cooking and cleaning.
Source: World Water Assessment Programme (WWAP)
In 2010, 89 % of the world’s population, or 6.1 billion people, used improved drinking water sources, exceeding the MDG target (88 %); 92 % are expected to have access in 2015. By 2015, 67 % will have access to improved sanitation facilities (the MDG target is 75 %).
Source: WHO - See more at: http://www.unwater.org/statistics_san.html#sthash.i71FPTao.dpuf