Water is a vital part for all creatures, however, huge variation exists between countries in terms of clean water availability. Most countries suffer from extreme shortage in water resources along with fast increase in population. This resulted in even more complicated problem that has a direct impact on the economical and development aspects of countries. This paper employs the Preference Selection Index (PSI) in selecting the most suitable water desalination process for different types of feed water. Seven water desalination technologies were compared: The electrodialysis, reverse osmosis, multi flash distillation, multi effect desalination, vapor compression, ion exchange and nanofiltration. A total of 12 criteria were considered in evaluating the selected desalination methods, these were related to the technology cost, lifespan, simplicity, reliability, quality and environmental impact. Results showed that the ion exchange is the most suitable desalination technology.