RO system maintenance is a rotation, not a single chore. The sediment and carbon prefilters are changed most often, the postfilter less often, and the membrane least of all, with an annual sanitize and a storage tank pressure check tying it together. Keep that rotation and the membrane, the expensive part, lasts years; skip it and the membrane pays the bill.
The cartridge rotation and why the order exists
Prefilters are sacrificial. The sediment stage catches grit that would abrade the membrane, and the carbon stage strips chlorine that would chemically destroy it, so both are changed on the shortest interval the maker publishes. The postfilter polishes taste after the storage tank and follows its own schedule. The membrane is replaced only when its performance actually falls off. Manufacturers publish the intervals for each stage on their product pages, and running prefilters past them quietly transfers their job to the membrane.
Sanitizing and the storage tank
Once a year, typically at a filter change, the housings and storage tank should be sanitized: the system is depressurized, cartridges come out, a sanitizing solution runs through, and everything is flushed before new cartridges go in. At the same visit, check the storage tank's air precharge with the tank empty; a tank that has lost its charge delivers a weak dribble at the faucet even when the membrane is healthy. These two checks catch most of the complaints people wrongly blame on the membrane.
Signs the membrane itself is failing
Three signals matter. Product water total dissolved solids creeping toward the feed water reading means the membrane is passing what it should reject; an inexpensive TDS meter makes this a moment's check. A tank that takes far longer to refill than it used to points at a fouled membrane, provided the prefilters are fresh. A return of flat or off taste after cartridge changes says the same. When those line up, replace the membrane and restart the rotation. If you are still assembling your system, our ro system installation guide covers getting the layout right from day one.
Questions people ask about ro system maintenance
What happens if I never change RO prefilters?
Chlorine and sediment reach the membrane, which is not built to survive either. The membrane fouls or degrades early, and it costs far more to replace than the prefilters that protect it.
How do I know when the membrane needs replacing?
Test the product water with a TDS meter. When its reading climbs steadily toward the feed water figure, or the tank refills abnormally slowly on fresh prefilters, the membrane is done.
Do RO systems need professional maintenance?
Most homeowners handle cartridge changes and sanitizing themselves; housings open with the wrench supplied. A technician is worth calling for persistent leaks or repeated membrane failures.