How to Store Used Reverse Osmosis Flat Membranes?

In water treatment, reverse osmosis (RO) systems stand out as one of the most effective methods for water purification. These systems heavily rely on their membranes for drinking or industrial use. But what happens when the system isn’t in use? Proper storage of these membranes is crucial for their efficiency and longevity. This article delves deep into how to store your used reverse osmosis flat membranes best.

How to Store Used Reverse Osmosis Flat Membranes?

Short-Term Storage of RO Membranes

When and Why?

Your RO system won’t need special treatment for short intervals, such as 24-48 hours of inactivity. However, to reduce the chance of organism growth, the system should be run for an hour every 24-48 hours.

The Steps:

  1. Routine Maintenance: Regularly run the RO system in work mode for an hour within every 24-48 hour gap.
  2. Optional Permeate Flushing: Some RO systems have the option of permeate flushing or automatic CIP flushing, ensuring the system remains in a “ready-to-run” state.
  3. Emergency Stop: If an immediate shutdown is necessary:
    1. Ensure membranes can be stored in the housing or disassembled and stored separately.
    2. Choose a preserving agent like 3.0% bisulfite, citric acid-based products, DPNPA or isothiazoline-based disinfectant, or a mix of 1% sodium bisulfite (food grade) and 18% propylene glycol.
    3. For drinking water RO systems, bisulfite is typically recommended. Follow a set procedure of cleaning in place (CIP), preparing bisulfite solution with RO permeate water, and ensuring the RO section is filled with the solution.
    4. Regularly monitor the pH and concentration of the solution. Ensure that the pH remains between 3.5 and 9.5.
    5. Before reoperation, flush the system and verify the residual disinfectant in the product water.

Long-Term Storage of RO Membranes

When and Why?

A more intensive maintenance procedure is necessary for more extended periods of inactivity.

The Steps:

  1. Cleaning: Start with an online cleaning of the system.
  2. Preparation: Fill the CIP tank with RO product water and add a low-pH cleaning agent.
  3. Circulation: Allow the solution to circulate within the RO unit for 15-20 minutes.
  4. Shutdown: Turn off the device and close all valves. The acid solution can either remain in the unit or be drained.
  5. Post-cleaning: Disassemble the membrane, letting it drip dry. Soak it in a solution containing 1% sodium bisulfite and 18% propylene glycol for 30 minutes, then seal it in a plastic bag (without soaking liquid).
  6. Storage: Store in a cool, dry place with temperatures between 10-20°C.


Whether taking a short break from using your RO system or putting it on hold for a more extended period, understanding how to store your reverse osmosis flat sheet membranes is essential. With proper care, you can ensure the longevity and efficiency of these membranes, making your water treatment process more effective and reliable. Always remember the health of your RO system starts with the health of its membranes!

FAQs on Storing RO Membranes

Why is short-term storage different from long-term storage?

Short-term storage prepares the membrane for quick reoperation, while long-term storage focuses on preserving membrane integrity over extended non-use.

Is it necessary to monitor the pH of the solution regularly?

Yes. Maintaining a pH between 3.5 and 9.5 ensures the membrane is not damaged due to acidic or alkaline exposure.

Why do we need a low-pH cleaning agent for long-term storage?

A low-pH cleaning agent ensures the system remains free from scale and microbial growth during extended periods of inactivity.

How long can a membrane be stored using the long-term method?

With the right conditions and method, the membrane can be stored for up to one year without compromising performance.

Is refrigeration required for long-term storage?

It’s beneficial. Maintaining temperatures between 10-20°C can enhance preservation.

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