Treat published intervals as starting points, then adjust for feed-water quality, usage and actual system performance.
Sediment prefilter
Typical replacement is around 6–12 months. Heavy sediment can shorten that dramatically.
Carbon prefilter
Typical replacement is also around 6–12 months. Carbon protects the membrane from disinfectants and can affect taste.
RO membrane
Many residential membranes last roughly 18–36 months, but feed chemistry, pressure and pretreatment can move that range significantly.
Post-carbon and remineralization
These are commonly changed around 6–12 months depending on design. Brand-specific proprietary systems should follow the exact cartridge schedule.
How to verify treatment claims for RO Filter Change Schedule: What to Replace at 6, 12 and 24 Months
Start with the contaminant or water-quality problem, then verify the exact finished system. Technology labels such as reverse osmosis, activated carbon, ion exchange or ultrafiltration describe a treatment mechanism; they do not prove that every product using that mechanism has the same reduction claims. For health-related contaminants, look for model-specific certification or a performance data sheet tied to the exact unit.
NSF/ANSI 42 commonly covers aesthetic effects such as chlorine taste and odor, NSF/ANSI 53 covers specified health-effect reductions, and NSF/ANSI 58 applies to reverse-osmosis systems. The presence of a standard number does not mean every optional contaminant claim in that standard was certified, so the individual listing still matters.
Flow, installation and three-year ownership cost
A filter that treats the right contaminant can still be a poor fit if the household dislikes its flow rate, reservoir workflow or installation requirements. Compare faucet flow, daily production, drain requirements, available cabinet or counter space and whether a powered pump or dedicated faucet is needed. Renters should give extra weight to reversible installations.
Then annualize the consumables. Add prefilters, membranes, postfilters or proprietary cartridges over at least three years and consider availability where you live. Higher-priced hardware can be the better value when filters last longer and remain easy to source; inexpensive hardware can become costly when several proprietary cartridges need frequent replacement.