PP sediment 3–6 months, carbon 6–12 months, RO membrane 24–36 months — lifespans differ sharply by stage, and time is not the only criterion.
Cartridge life depends on three things: feed-water quality, daily consumption and the cartridge specification. The same PP filter may clog in two months in high-turbidity areas and last six months where water is clean.
Rules of thumb: PP sediment 3–6 months; granular and carbon block 6–12 months; RO membrane 24–36 months, judged together with TDS rejection — replace when rejection drops noticeably or flow falls by more than 30%.
For OEM brands, putting the replacement interval into the manual and packaging is the most direct way to reduce after-sales complaints.