The subject title is mis-leading. After all reverse osmosis is known for decades and huge plants for purification of water are in place throughout the world. Further, there are advantages and disadvantages for both ion-exchange resin systems and RO systems. Decision on using RO over ion-exchange resin systems depends on the quality of the water to be treated and the cost benefit analysis. When ultrapure water is required, even though RO is used as a pretreatment process, the final high purity can be achieved only using mixed bed ion-exchange resin columns.

RO systems do need chemicals to keep the membranes in good working condition. In fact, this cost is substantial and next only the electrical energy required for operating the RO systems.

If Siemens have made any innovations in their RO systems over and above what is presently known, they could perhaps high-light such information rather than making this misleading announcement.

H.S.Gopala Krishna Murthy