How Long to Flush RO Membrane?

Reverse Osmosis (RO) systems have increasingly become essential to water purification across industries and households. Just like any sophisticated system, the RO Membrane demands regular maintenance. One key aspect of its upkeep is membrane flushing. This comprehensive guide delves deep into understanding the whys, whens, and hows of flushing your RO membrane.

RO Membrane Flushing

Why is Flushing the RO Membrane Essential?

Flushing the reverse osmosis membrane is a maintenance necessity. This process ensures:

  1. Prolonged Service Life: Regular flushing can extend the membrane’s lifespan, ensuring its optimum functioning for longer.
  2. Stable Water Quality: Proper maintenance ensures the water remains stable and high quality.
  3. Prevention of Contamination: Regular flushing helps keep the membrane free from contaminants and prevents heavy build-ups.

When Should You Flush the RO Membrane?

It’s vital to recognize when your RO membrane needs cleaning:

  • Performance Indicators: If the standardized water production decreases by more than 10%, the pressure difference between feed and concentrated water increases by over 15%, or the salt penetration rate increases by more than 5%, it’s time to act.
  • Regular Monitoring: Always implement regular checks and data recording. Any pollution impact on the membrane is gradual. Therefore, the cleaning cycle could vary between 3-12 months based on the contamination level.
  • Before Long-term Shutdowns: If you plan to shut down the system for an extended period, ensure you clean the membrane beforehand.

Quick Tip

When the membrane is only slightly polluted, a simple cleaning will suffice. However, for heavily polluted membranes, replacement is advisable.

How Long to Flush RO Membrane?

Experts recommend flushing your RO membrane 2-3 times, lasting around 10-20 minutes or until the water runs clear. To maximize membrane longevity and maintain consistently high water quality, thoroughly clean the membrane monthly. This proactive approach extends the membrane’s service life and ensures the stability and excellence of your water quality.

How Long to Flush New RO Membrane?

When installing a new RO membrane, it’s vital to rinse it for at least 1 hour. This duration ensures that all the protective solution is thoroughly washed away, while the protective solution will compromise the quality of the water produced, making it substandard. A more extended flush of at least 24 hours is recommended for those using the resulting water for drinking purposes. This ensures that all impurities, solvents, and residual protective solutions are entirely removed from the system.

Why is Flushing New RO Membrane Necessary?

When a new RO membrane is dispatched from the factory, it’s coated with a protective liquid. This is not a manufacturing oversight or a defect; it’s done purposefully to shield the membrane during storage and transit.

The Purpose of the Protective Liquid

The protective liquid plays a crucial role in maintaining the integrity of the RO film. It prevents it from drying out and ensures the membrane remains effective when used. However, as essential as this protective layer is, it’s not something you’d want in your filtered water. This brings us to why flushing a new RO membrane is non-negotiable.

How to Flush RO Membrane? Step-by-Step Guide

  1. Preparation:
    • Close the reverse osmosis inlet and outlet valves.
    • Open the side valve of the RO flushing pipeline.
  2. Inject Cleaning Solution:
    • Activate the cleaning solution tank and pump.
    • Introduce the cleaning solution, commonly a sulfuric acid, into the RO system.
  3. Circulate the Solution:
    • Allow the cleaning solution to circulate for about 15-30 minutes.
    • Adjust the cycle time based on specific needs.
  4. Rinse the Membrane:
    • Deactivate the cleaning solution pump and tank.
    • Open the RO inlet and outlet valves, letting clean water flow through to remove any residual solution.
  5. Post-cleaning Operation:
    • Let the RO system run for a while post-cleaning to ensure water replacement throughout the system.

Safety Precaution

Always check the system’s functionality before flushing. Adhere to user manual guidelines and avoid skin, eye, and clothing contact with the cleaning solution.

Precautions to Observe

  • Optimal Pressure: Ensure the pressure during cleaning is such that the system barely produces pure water.
  • Cleaning Solution Quality: Prepare the cleaning solution using RO product water or deionized water. Ensure it’s mixed uniformly.
  • Solution Reuse: Prepare a fresh batch if the reused cleaning solution is discolored or turbid. Also, monitor pH changes and adjust or replace the solution if needed.
  • After-Cleaning Process: Rinse with RO product or deionized water post-cleaning for 30-60 minutes. Always try to put the system back into operation within 24 hours of chemical cleaning.


Keeping your RO membrane in tip-top shape extends your system’s lifespan and guarantees you’ll get high-quality water every time you turn on the tap. Regular flushing is the key step of this maintenance routine. You’ll keep your RO system performing at its best for years by getting the timing, steps, and precautions right.

FAQs on RO Membrane Flushing

How often should I flush my RO membrane?

Experts recommend flushing the membrane once a month. Doing so regularly prolongs the membrane’s life and maintains consistent water quality.

How long does each flushing session typically last?

Typically, it would be best to flush the membrane 2-3 times, with each session lasting 10-20 minutes, until you see the water run clear.

What type of cleaning solution should I use for flushing?

Typically, use the cleaning or sulfuric acid solution that comes with the new RO membrane. Always adhere to the manufacturer’s guidelines.

What is the difference between preventive cleaning and emergency cleaning?

Perform regular preventive cleaning to avoid fouling and extend the membrane’s lifespan. Conduct emergency cleaning when you notice significant fouling or a drop in water quality.

Should I clean the RO membrane myself?

Although users can perform the process, we recommend hiring professionals to prevent damage to the membrane elements and adhere to proper cleaning procedures.

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