The RO membrane is the workhorse of the water purification system. It uses a thin film (membrane) technology to reject impurities. RO membranes are especially good at rejecting large atoms, molecules, and other items that exhibit a relatively strong electron charge. It is less effective in rejecting small atoms, molecules smaller than water, and those with relatively weak electron charge. RO membranes will allow all dissolved gases, including ammonia and carbon dioxide to pass through. The percent rejection rating for a membrane is an indication of how many of these impurities will pass through the membrane and on to the DI cartridge.

A membrane that has a 98 percent rejection rating will pass about half of the impurities that a membrane with a rating of 96 percent will pass. The direct result of using a 98 percent rejection membrane as opposed to a 96 percent membrane, is that the life of your DI cartridge will be doubled. It is important to note that all membrane manufacturers adhere to a lower percent rejection limit for small membranes, which means that you need to purchase your membranes from a source that screens for higher rejection rates to ensure that you are getting the quality you need.

Our experience has been that not all RO membranes are the same. SpectraPure's membranes are treated with a proprietary process to enhance percent rejection and production characteristics. We have been testing our RO membranes for more than 20 years, using the industry standard of 60psi. We have a significant amount of data to draw upon when sharing performance characteristics with our customers.

Rejected membranes are sold to another, far less demanding market. The difference in price reflects some of our investment to perform necessary testing. The price difference between a membrane that is tested and a membrane that is untested becomes insignificant when you obtain a one or two percent improvement in rejection and the life of your DI cartridge is extended. Even our untested membranes are subjected to a proprietary process which increases their rejection ratio over units purchased by other vendors from the same supplier. Those who claim that all membranes from a particular vendor are exactly the same may not be aware of the intensive testing processes we use to increase our rejection rates.

Critical products like membranes, DI cartridges, filters, housings, gauges, valves, and pumps are exhaustively tested and analyzed in the lab and field, to make sure they meet our performance standards before you make your purchase.