The main water purification/desalination processes currently in use fall under two categories: Thermal desalination and reverse osmosis. Of the two, reverse osmosis is more efficient and cost effective. However, the process is not without its kinks. The membrane used to filter impurities is susceptible to microbes in the impure water. As a result, a chlorine wash is necessary to combat the bio-film that collects on the membrane surface. Unfortunately, current membranes are significantly weakened by exposure to chlorine. -------------------------------------------------- johnyymathew Opinion Leader