Water knowledge
Signs Your RO Membrane Needs Replacement
By SACHSTAR · Editorial update: 9 October 2026
The short answer
Reduced output or a change in inlet-to-output TDS reduction can justify a membrane inspection. These symptoms do not identify the failed part by themselves; feed pressure, pre-filters, bypass settings and other faults also need checking.
Signals worth investigating
- The tank takes longer to fill under comparable conditions.
- Output TDS has changed compared with previous service readings.
- The system runs unusually long or stops producing water.
- Source water or pretreatment conditions have changed.
Why diagnosis comes first
A clogged filter, pressure problem, faulty pump, bypass or connection issue can resemble a membrane fault. Ask for the checks and measurements that support the diagnosis. A TDS comparison helps assess dissolved-solids reduction but does not test for every contaminant.
Confirm compatibility before fitting
- Membrane type, rated capacity and manufacturer compatibility.
- Housing, pump and pressure requirements.
- Feed-water operating limits and pretreatment needs.
- Flushing procedure, replacement price and warranty terms.
After the work
Ask for a record of the fitted part, commissioning readings and manufacturer instructions before normal use. If water quality is in doubt, use a known safe source while the system and water are assessed.