This study explores the current situation of the membrane desalination market; it estimates how many countries and which ones will suffer from water scarcity by 2050 and presents three case studies (India, China and Algeria). Finally it highlights some challenges for the implementation of desalination in water scarce countries. The projections in this study indicate that 44 countries (2 billion people) will suffer from water scarcity by 2050, i.e. their available water resources will be less than 1000 m³/cap/year. Thirty five of these countries (1·9 billion people), which correspond to 95% of the total population in water scarcity countries will live in developing countries by 2050. Moreover, case studies performed in this study showed that some developing countries such as India and China have already turned their industries to desalination and this strategy may be applied in other countries. However, desalination is still energy intensive and produces considerable amounts of Green House Gas emissions. Therefore, the need for resource saving, low impact green desalination technologies is evident to solve water scarcity in many parts of the world.