How to Determine Whether the Membrane Of Reverse Osmosis System Needs Replacement？
ONE、Refer to the three core performance indicators (most accurate approach): If any one of the following criteria is met and chemical cleaning proves ineffective, the membrane must be replaced:
1.Significant decline in permeate flow rate
Under the same pressure and temperature conditions, the permeate flow rate has dropped by 15% to 20% or more compared to when the membrane was new, and cannot be restored after chemical cleaning.
→The membrane is fouled/deteriorated and must be replaced.
2.A significant decrease in salt rejection rate and a marked increase in permeate conductivity
The salt rejection rate drops from 98% to below 95%, or even lower, and does not recover after chemical cleaning.
→The membrane has suffered perforation, degradation, and damage, and must be replaced.
3.Excessive interstage differential pressure
The differential pressure of the first stage and the total differential pressure are 15% to 20% higher than the initial baseline values, and the pressure does not drop after chemical cleaning.
→Severe blockage of membrane channels is beyond recovery and requires membrane replacement.
TWO、Observing Operational Indicators (Judging Without Instruments)
High operating pressure with abnormally low permeate flow.
→The membrane is completely fouled.
Sudden spike in permeate conductivity, accompanied by a salty taste in the product water.
→Membrane oxidation damage or O-ring leakage
Cleaning leads to progressive performance deterioration and fails to yield any improvement.
→The membrane is irreversibly fouled and must be replaced.
Service life exceeded but performance remains normal.
RO membrane lifespan: 2 to 3 years
Poor feed water quality and inadequate maintenance: the membrane may fail within 1 to 2 years.
→When the design service life is reached, replace the membrane directly — do not attempt to extend its operation.
THREE、Membrane replacement is not required in these situations — don't be misled!
- Permeate production declines, but recovers significantly after chemical cleaning.
- Isolated high differential pressure that fully normalizes after chemical cleaning.
- It's just an intermittent conductivity fluctuation caused by O-ring or connection fitting issues.
These are cases of fouling or minor faults — cleaning or repair will resolve the issue, and membrane replacement is unnecessary.