Pretreatment Failure Leads to Membrane Element Oxidation
This is a hidden fault easily overlooked by many users. Residual chlorine and oxidizing substances in the raw water are not completely filtered out, continuously corroding the reverse osmosis membrane layer and gradually damaging its desalination function, resulting in a sustained, slow decline in the desalination rate.
In a previous pharmaceutical water project, this client had not replaced the activated carbon filter for three consecutive months, causing the pretreatment to completely fail, and the residual chlorine content in the influent exceeded the standard by 0.3 mg/L. Visually, there was no abnormality in the water quality, yet the desalination rate of the equipment decreased by 2 percentage points each month. We replaced the activated carbon filter on-site with a brand new one, completely replacing the oxidized surface membrane water, followed by a professional maintenance cleaning. The desalination rate immediately rebounded to 98.9%.
Industrial Reverse Osmosis Equipment
Membrane Surface Scaling and Contamination
In reverse osmosis equipment operating continuously for extended periods, calcium and magnesium deposits, silica scale, and organic matter in the water adhere to the surface of the reverse osmosis membrane, clogging the pores. This prevents effective salt retention, naturally leading to a continuous decrease in desalination rate. This fouling is not due to hardware damage and can be resolved through cleaning without membrane replacement.
One chemical company client had their equipment not chemically cleaned for eight consecutive months last year, resulting in severe membrane scaling and a sharp drop in desalination rate from 99% to 92.1%. We formulated an acid-base cleaning agent based on the specific situation and implemented a segmented, circulating cleaning and maintenance operation, taking four hours in total. After cleaning and water recirculation, the equipment's desalination rate immediately rebounded to 98.7%, saving tens of thousands of dollars in membrane replacement costs.
Leakage Due to Aging of Membrane Module Sealing Accessories
The O-rings and gaskets inside the membrane housing of a reverse osmosis system are vulnerable parts. Prolonged exposure to water pressure and corrosion can cause them to age, deform, and crack, leading to short-circuiting of raw water into the permeate and a rapid drop in desalination rate.
Inappropriate Operating Parameter Settings
These parameters—inlet water pressure, recovery rate, and water temperature—may seem insignificant, but they directly impact the desalination performance of the reverse osmosis system. Insufficient inlet water pressure or excessively high recovery rates increase the filtration burden on the membrane, causing salt to permeate and ultimately lowering the overall desalination rate.
Permeate Element Performance Degradation
Any membrane used in reverse osmosis has a limited lifespan, typically between 3 and 5 years. (Click to view: How often should reverse osmosis membranes be replaced? Factors affecting lifespan) Once the recommended lifespan is exceeded, the membrane's layered structure will naturally age, gradually reducing its ability to block salt permeation. This is an irreversible physical loss, and the only solution is to replace the membrane with a completely new one.
Infeed Water Quality Fluctuations
Changes in the raw water source, such as a drop in groundwater levels or surface water mixing during the rainy season, can cause a sudden increase in TDS, hardness, and iron/manganese ion concentrations, exceeding the equipment's designed processing capacity and consequently reducing the desalination rate.
For more information on reverse osmosis equipment malfunctions, please refer to the 2026 updated version of the article "Reverse Osmosis Equipment Maintenance and Troubleshooting Techniques." To what extent has the desalination rate of your reverse osmosis unit dropped? Have you tried cleaning or replacing the seals? Feel free to share your repair experience in the comments section. Like and save this article so you can directly refer to it for troubleshooting next time you encounter a problem. This is both time-saving and cost-effective!
