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Replacing the membrane of a reverse osmosis system is probably the most important part of maintaining the unit in a good condition.
This doesn’t have to be done too often – usually, an RO membrane can last for 2-5 years without any issues.
For some people, this raises the question of whether it makes sense to look out for discounts and buy membranes cheaply to store them for later on.
But is that a good idea? What’s the shelf life of an RO membrane?
If it’s never taken out of its original packaging, a reverse osmosis membrane does not have a shelf life – it can last pretty much indefinitely in storage. It’s very important to avoid breaking the packaging though, as this will compromise the membrane in the long run.
If a membrane has already been used, meaning it got wet, it can never be dried and stored in this manner. You must use a special solution to store the membrane in this case, otherwise you risk the development of microorganisms which can make the use of the membrane hazardous.
Although storing a reverse osmosis membrane in a preservative solution is not something you would usually do on your own at home, sodium bisulfite can be used for this purpose. Storage time for preserved RO membrane elements is up to one year.
Try to keep the storage temperature low, but not too low. The ideal range is between 50°F (10°C) and 95°F (35°C). The membrane should be kept in a dry, dark place.
If the membrane has been in use, it must be stored in a preservative solution. In this case, storing between 22 and 113°F (-5°C and 45°C) is possible – out of direct sunlight.
On average, a reverse osmosis membrane tends to last for 2-5 years before it needs to be replaced. There are various factors that can influence this though.
The harder your water is, the faster it will wear down a reverse osmosis membrane. Hard water results in scaling on the membrane, which makes it clog up faster.
If you’re using a TFC (Thin Film Composite) membrane, it should last longer than a CTA (Cellulose Triacetate) one. CTA has mostly been phased out in the production of modern RO membranes, so if you bought yours recently, there’s a good chance it’s TFC anyway.
Heavily contaminated water can result in your RO membrane wearing out faster and requiring more frequent replacements. The same goes for all additional filters you use in the system.
A larger household with more people drinking water every day will naturally place more strain on the RO membrane. You may need to replace it more often if you live with multiple people who all share the same RO system.
If you have any questions about RO membrane shelf life please don’t hesitate to leave a comment below!
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