RO Maintenance: Filters, Membranes and Slow Flow

Identify the model before buying parts

RO systems vary in filter connections, membrane specifications, storage arrangements and service procedures. Record the model and replacement part numbers. A kit advertised for the same number of stages may still be incompatible. Follow the manufacturer rather than assuming all under-sink systems use the same components.

Separate filters from the membrane

Prefilters protect the system and postfilters may affect taste; the membrane performs a different role. They may not share one replacement interval. Ask the provider to distinguish scheduled cartridge service from membrane replacement and to document the basis for changing each component.

Describe slow flow precisely

Does the faucet run slowly from the beginning, or does the system run out after a long draw? Supply pressure, tank condition, restricted filters, valves and membrane condition can produce different patterns. Note whether a refrigerator also uses the system and whether the symptoms started after plumbing work.

Include sanitation and flushing

Ask which sanitizing and initial-flush procedures the manufacturer requires. The quote should include leak checks on housings, tubing and shutoffs and explain when water can be used again. Replacing a cartridge without addressing a cracked housing or failed valve does not complete a repair.

Keep a small service record

Record dates, part numbers, symptoms and any appropriate feed and treated readings. A TDS reading is a useful operational clue for some assessments, but it is not a comprehensive safety test. If the concern is a specific contaminant, use the appropriate test and exact product reduction claim.

Choose maintenance or diagnosis

Use RO filter and membrane replacement for a defined service interval and RO repair for an unexplained fault. Confirm the provider's scope, parts and appointment terms before authorizing work.