It affects every continent, hinders sustainability, and limits social and economic development. Although the global average water stress is only 11 per cent, 31 countries experience water stress between 25 per cent (when stress begins) and 70 per cent, and 22 countries are above 70 per cent and are seriously stressed. The highest stress levels occur in Northern Africa and in Western, Central and Southern Asia. Levels of stress are likely to increase as populations and the demand for water grow and the effects of climate change intensify.