Water will become the most sought-after natural resource most likely to cause wars in the 21st century, according to the World Bank. Chronic water shortages already affect 40 per cent of the world’s population in 80 countries and the situation is set to become far worse with an expanding population and ever-increasing demand for water. Whereas the main constraint on food production in the developing world has in the past been a shortage of land, it will be a scarcity of water in the future, according to a study by the World Bank. Global demand for water is increasing at a rate of 2.3 per cent a year, doubling every 21 years. ”Supply can no longer keep up with this rate of growth,” the World Bank warns. A billion people in the world today do not have access to clean drinking water and almost as many again lack adequate sanitation facilities.