Desalination refers to any of several processes that remove excess salt and other minerals from water. Water is desalinated in order to convert salt water to fresh water so it is suitable for human consumption or irrigation. Most of the modern interest in desalination is focused on developing cost-effective ways of providing fresh water for human use in regions where the availability of fresh water is limited. This book reviews research in the field of desalination including the growth of scientific and commercial interest to cogenerative and hybrid technologies for desalination and power generation; Membrane Distillaion (MD) process as a new membrane technology used for desalination and recycling; two alternative systems for conventional reverse osmosis desalination plants by incorporating the use of gravitational potential energy and others.