Reverse osmosis (RO) is one of the most effective processes for providing a consistent supply of high purity water in healthcare applications.
Typically, an RO system works by feeding a conventional mains supply under pressure into a module containing a semi-permeable membrane. The membrane removes a high proportion of impurities, including up to 98% of inorganic ions, together with virtually all colloids, micro-organisms, endotoxins and macromolecules, with almost 70% of the feed-water passing through the membrane as a purified permeate, with impurities being removed in a residual concentrate stream that is run to drain.
RO systems generally include a pre-treatment package designed to meet the characteristics of the feed-water. Typically, this equipment includes a base-exchange softener to remove hardness that would otherwise scale the membranes. Further protection being provided by passing the water through activated carbon filters, to remove free chlorine and organic contaminants, with any remaining particulates being removed by a fine filter before the pre-treated water enters the RO plant.

For applications that require even higher purity water, such as Heamodiafiltration, it is normal to use double pass reverse osmosis. This involves processing the permeate through two sets of membrane filters, but produces water that has extremely low levels of endotoxins and bacteria.
Finally, portable and self-contained containerised RO units can be located outside hospital buildings to maximise the space available internally. These systems can be installed quickly and simply, with a minimum of disruption to hospital schedules; once in place they have low operating costs, requiring minimal maintenance or user intervention, and can be used to provide a 24/7 supply of high purity water.

Economic RO system water treatment machine