How Do Reverse Osmosis Membranes Work?

As one of the most common and popular forms of water filtration methods in the world, the term reverse osmosis gets surprisingly little recognition from the general public. Some people may recall that it is a kind of system or process through which water is purified, but for most people the actual mechanical function and inner workings of reverse osmosis systems are still something they cannot comprehend. Even people who regularly use RO systems in their home may have a hard time explaining how they work to a stranger. This doesn’t have to be the case because the acutal mechanics, operations and technical functionalities of a reverse osmosis system is not very complicated.

From small under-counter kitchen RO systems to large warehouse filled RO treatment centers, the process of reverse osmosis water filtration is the same. Thin-Film Composite (TFC) membranes are created from multiple sheets or leaves of polyamide layered with polysulfone and polyester support webs which are then rolled together over a purified water delivery tube. The membrane element is then placed in a housing chamber that is designed to separate the purified water (permeate) from the rejected (concentrate) water. When a sufficient water pressure is applied to the chamber, water will flow through the membrane channeling in a spiral direction from the top layer sheets down towards the center tube. The many membrane layers provide both a delivery path for the water and a filter barrier for water contaminants. The water that ultimately makes its way down to the center tube will have passed through multiple membranes leaves where 90-99% of the dissolved solids are captured and transported away through a separate waste line. The purified water molecules that pass unimpeded through the membrane will then flow out from the inner tube to be collected and stored for later use.

TFC elements use an innovative crossflow design that utilizes the existing water pressure and flow to rinse and clean the membrane layers throughout the entire filtration process. The membrane is continually flushed and contaminants are carried out of the vessel on a separate line which reduces waste buildup and accumulation in the element. This feature helps protects the membrane from clogs and obstructions caused by bio-fouling, scale hardness and contaminant saturation and this allows the membrane to last 4-5 years before replacement is needed.

Learning how a reverse osmosis system works for the first time may seem intimidating and complex, however, the actual operation of these systems is very simple and trouble-free. Average people from all walks of life have owned, installed and maintained their own home RO systems completely with the need of professional assistance. With a very minimal amount of maintenance and care, most RO systems will last many years and provide your family with an unlimited supply of safe, healthy drinking water.