Guides · Maintenance
How to Flush a New Cartridge
Why the first litre after a cartridge change tastes wrong, the flush steps manufacturers actually specify, and what to do with the water.
Why new cartridges need flushing
Carbon cartridges shed fine particles when new, and some media carry a residual taste from manufacturing. RO systems also need their storage tank and post-filter rinsed.
The flush is not superstition: it is the manufacturer's way of clearing fines before you drink the water.
What the manual typically says
Pitchers: soak or rinse the cartridge, then discard the first one or two pitchers of water. Many manufacturers also ask for a 15-minute soak before first use.
Faucet-mount and under-sink carbon: run 1–5 minutes to drain, or the manual's stated number of gallons.
RO systems: discard the first tank (typically 2–3 gallons), and some manuals ask you to repeat once. Post-filter flush instructions vary, so read the model-specific page.
Doing it without wasting the water
Catch the flush water in a bucket or large pitcher. It is fine for plants, dishes, cleaning, or the kettle base — just not for the first glass.
Use the same routine every time you change a cartridge. A habit survives a busy week better than a note on the fridge.
After the flush
If the water still tastes off after the full flush, check that the cartridge is seated correctly and that any protective wrap or cap was removed.
A persistent plastic taste in an RO system can mean the post-carbon cartridge was installed backwards or the tank needs draining again.
If a cartridge leaks after flushing, stop and reseat it before running the system unattended.
Recording the change
Write the date and the cartridge model number on a sticker inside the cabinet or on the unit. The rated interval starts today, not at purchase.
If your system has multiple stages, note which stage you replaced. Changing them out of order is a common and expensive mistake.
FAQ
Quick answers
+Can I skip the flush to save water?
You can skip the wait, not the flush. The fines and residual taste are the reason the step exists, and a small pitcher of discard water is cheaper than a spoiled first impression.
+How long until the water tastes normal?
Usually within the manufacturer's flush volume. If the taste persists well beyond that, check the seating and orientation of the cartridge.
+Do I need to flush a sediment pre-filter?
Briefly, yes — enough to clear loose material. Sediment cartridges have no carbon fines, so the manual's flush is typically much shorter.