The central element of any reverse osmosis water filter is the semi-permeable reverse osmosis membrane. Of course, the membrane alone is not sufficient to deal with every and all types of tap water contaminants, which is why most reverse osmosis filters are complex, multi-stage systems that comprise several types of filter media (e.g. activated carbon, ceramics, polypropylene, etc.) to achieve the in-depth filtration reverse osmosis systems are known for.

reverse osmosis membrane

The maintenance of a reverse osmosis filter involves the periodic replacement of the filter cartridges that make up the system along with the replacement of the RO membrane. While replacing the filter cartridges in a reverse osmosis system is a straightforward and simple process, replacing the RO membrane follows a slightly different procedure.

RO membrane replacement guide

Unlike the other filters that make up the reverse osmosis system, the reverse osmosis membranes will last anywhere from 1 to 3 years, or even more, depending on the membrane model and the chemistry of your water. If your water is hard and you’re putting a lot of water through the system, you may find yourself replacing the membrane more often than what is recommended by the manufacturer. A TDS (Total Dissolved Solids) meter can actually help in determining whether you need to replace your membrane.

Shut off the water going into the RO system and shut off the reverse osmosis tank

Once you have the replacement membrane that is compatible with your system, before you attempt to replace the old membrane, make sure you shut off the water flowing into the RO system and the tank that services the system.

Disconnect the tubing going into the membrane housing and remove the membrane from its housing

To get to the membrane, you need to disconnect the tubing that connects to the large end of the membrane housing. Make sure you have towels placed on the floor or use a bucket to capture the water that will come out of the system. Disengage the housing, remove the cap on the membrane housing and by using a pair of needle nose pliers remove the membrane with a twisting motion.

Discard the old membrane and insert the new membrane, then flush the membrane

To make sure the membrane housing is fully sealed, you may use plumbers’ silicone grease to lubricate the O-ring and the main seal. The process of flushing the membrane takes a bit more time. Turn on the water supply and the RO tank, allowing the system to refill it. Wait about two hours, then turn on the faucet letting the air out of the system and flushing the membrane. Repeat the flushing process at least two times, waiting for at least 2 hours between each procedure.

Test your water to see if it tastes good. If you notice a strange taste, repeat the flushing process once more.