African nations led by Somalia, Mauritania and Sudan have the most precarious water supplies in the world while Iceland has the best, according to a survey that aims to alert companies to investment risks.
The ranking, compiled by British-based risk consultancy Maplecroft, said climate change and a rising world population meant that stresses on supplies would be of increasing concern in coming decades for uses from farming to industry.
It notes that London-listed mining multinationals Anglo American and Rio Tinto are seeking to reduce their water usage.