Water knowledge
How Often Should RO Filters Be Changed?
By SACHSTAR · Editorial update: 9 October 2026
The short answer
Follow the replacement schedule for your purifier and fitted cartridges. Water quality and heavy use may require earlier service; normal taste or appearance is not a reason to extend a manufacturer’s replacement limit.
Different parts need different schedules
Sediment filter
Traps suspended material such as sand and rust. A restriction can reduce flow, but appearance alone cannot determine the remaining service life.
Carbon cartridge
Reduces specified substances such as chlorine or some taste and odour compounds. Its capacity is finite and cannot reliably be judged by looking at it.
RO membrane and post-treatment parts
Have their own operating and replacement instructions. Compatible parts and timely pretreatment maintenance matter.
What may require earlier inspection
- Flow or filling speed changes.
- Water source, daily demand or inlet quality changes.
- A manufacturer alarm or service reminder.
- Taste, odour or output readings change.
- The unit has been unused for a long period.
Keep a useful service record
Write down each fitted component, installation date, replacement date and the manufacturer’s next recommended interval. Ask the technician to note inspections and flushing or sanitisation instructions. This is more useful than one generic replacement interval for every model.
What to ask before replacing
Confirm the cartridge specification, compatibility, price and labour charge. Ask whether other work is recommended and why. Do not assume a same-sized filter has the same treatment performance.