While the world's population tripled in the 20th century, the use of its renewable water resources grew six-fold.

Within the next 50 years, the world population will increase by another 40% to 50%. This population growth - coupled with industrialisation and urbanisation - will result in an increasing demand for water and will have serious consequences for the environment.

Although food security has been significantly increased in the past 30 years, this improvement has depended on increasing the use of water for agriculture. Irrigation represents 66% of total water withdrawals (up to 90% in arid regions); the other 34% is used by domestic households (10%) or industry (20%), or has been evaporated from reservoirs (4%).

As per capita use increases with changes in lifestyle, and as population increases, the proportion of water for human use is increasing. This, coupled with spatial and temporal variations in water availability, means that the water to produce food for human consumption, industrial processes, and all the other uses is becoming scarce.

There is more wastewater generated and dispersed today than at any other time in history - a time when 3,900 children die every day from waterborne diseases, more than 1 out of 6 people lack access to safe drinking water, and more than 2 out of 6 lack adequate sanitation (a total of 2.6 billion people).

Water is a renewable - though finite - resource. "The crisis is not about having too little water to satisfy our needs. It is a crisis of managing water so badly that billions of people - and the environment - suffer badly."