If action is not taken, by the year 2025, two-thirds of the world's population will live in areas with unstable water supplies. The global water problem is the result of several factors, most prominently the growing population. More people means more demand for water for domestic, agricultural, and industrial use. The growing population must eat. Production of a ton of grain requires roughly 1,000 tons of water.
Uneven distribution is also a factor.
For example, Africa's Niger Delta receives significant quantities of rain, while the nearby Sahara Desert gets very little. According to GEO-2000, there are 50 African rivers that provide water to two or more countries. The potential exists for armed conflict when the demand for water from these rivers outgrows the supply. Even when there are adequate water supplies, the water is not necessarily safe to drink. Sewage is a serious threat to water sources.