The post-carbon filter is the small capsule-shaped inline filter, usually the last stage before the tap. It is cheap and easy to replace – and it is the first thing to change if your RO water tastes stale.
What does the post-carbon filter do?
Water sits in the storage tank for hours. The post-carbon filter polishes taste and removes any odour picked up in the tank, just before the water reaches your glass. It works like the pre-carbon stage but on already-purified water.
Pre-carbon vs post-carbon
| Pre-carbon (CTO/GAC) | Post-carbon (inline) | |
|---|---|---|
| Position | Before the membrane | After the tank, before the tap |
| Main job | Remove chlorine to protect the membrane | Polish taste and smell |
| Size | 10 inch cartridge (usually) | Small inline capsule |
| Guide | Carbon filter guide | This page |
Post-carbon and inline filters on our store
See all inline filters. Many purifiers also have a mineral or alkaline inline stage – see copper vs alkaline RO.
When to change it
- Every 6–12 months for most homes.
- Immediately if water from the tap smells or tastes stale even after draining the tank.
- When you change the RO membrane, change the post-carbon too.
How to replace an inline filter
- Switch off the RO and close the tank valve.
- Note the flow direction arrow on the old filter.
- Press the collet on each push-fit end and pull the pipe out (or unscrew the elbows, if threaded).
- Fit the new filter in the same flow direction, push the pipes in fully and lock the clips.
- Open the tank valve, run the tap for 2–3 minutes to flush carbon fines.
Need connectors? See RO connectors and elbows.
Frequently asked questions
Can I skip the post-carbon filter?
You can, but water may taste stale after sitting in the tank. It is cheap, so it is worth keeping.
Why is water black after changing post-carbon?
Loose carbon fines. Flush the tap for a few minutes until it runs clear.
Do all inline filters fit all purifiers?
Most use 1/4 inch connections; check the length and fitting type before buying.
Need help choosing the right part? Send a photo of your RO or its model name on WhatsApp (96252 23245) and we will tell you exactly what fits. Original parts at wholesale rates, Cash on Delivery and All India delivery.
Need the right part for your RO?
Original filters, membranes and pumps at wholesale rates. Send us a photo of your RO – we will tell you exactly what fits.
