Mekorot＇s activities and achievements in the implementation of RO technology to solve water supply and quality problems were reviewed. Two design concepts were applied: optimal usage of basic resources for large capacity systems, and simplicity in design and operation for small systems at remote locations. Special efforts are directed to minimize negative impacts on the environment. Existing systems of both large and small capacities, along with systems under design are being reviewed, including cost breakdown and analysis. The large capacity systems are characterized by high product recovery and low specific energy consumption. In two specific cases brine disposal cost has a negative value. In one case, the brine is used for raw seawater blending for a SWRO plant, and in another case, concentrating the brackish source via desalination facilitates the solution of an environmental problem.