Replacement timing is not universal
The same cartridge can age differently in two homes. Consumption, sediment load, source-water variation and operating conditions all affect service life.
Ask for a service record
Keep the model, installation date, component changes, measured observations and technician notes in one place.
Watch performance, not only dates
Changes in flow, taste, odour, noise or operating behaviour should be discussed with the service team rather than ignored until a calendar date.
Confirm costs before work
Ask for the parts, labour, travel and any testing charges before approving maintenance outside the included warranty.
Protect the membrane
Appropriate pre-filtration, correct pressure and timely replacement of protective stages can help avoid unnecessary strain on the RO membrane.