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Inline Coconut Carbon Post Filter — Taste Polish, 10″ × 2″
PAC-QC
Post filter · Taste polish
This page covers where the filter goes, how to install it, when to change it, and the parts that fit it.
Is this your filter?
Check these against the filter in your hand. All four should match.
- ✓A white inline filter about 10″ long and 2″ across
- ✓The label says PAC · coconut activated carbon · post filter, taste polish (dark blue)
- ✓1/4″ quick-connect ports at both ends and a flow arrow on the label
- ✓SKU / Reorder # PAC-QC on the label, and a QR code that opens this page
Post filter or stage 2? Check the label
- PAC — post filter, after the RO membrane (dark blue label) — this page. It gives RO water its final taste polish.
- CAC — pre-carbon, stage 2, before the RO membrane (light blue label). Same coconut carbon, labeled for its position so the two never get mixed up. CAC-QC support page →
- Mineral or alkaline filter — goes after this filter, as the very last stage. Alkaline filter (ALC-QC) →
- Other inline filters (sediment, DI, specialty) — see the full guide. Inline filter guide →
Specifications
| Model / SKU | PAC-QC |
| Media | Coconut-shell activated carbon |
| What it does | Final taste polish for RO water: reduces taste and odor picked up in the storage tank and tubing, and any chlorine taste left over. It does not reduce fluoride, hardness or dissolved solids (TDS). |
| Position | After the RO membrane (and after a DI filter, if you have one) · before any mineral or alkaline filter |
| Size | 10″ × 2″ |
| Connection | 1/4″ quick connect · elbow adapters for 3/8″ OD tubing |
| Pressure / temperature | Max 90 PSI · 36–100°F, cold water only |
| Typical life | 12 months or 1,500 gallons (sooner if a stale or plastic taste returns) |
| Brand | MyWaterClub |
Reorder this filter
This filter · PAC-QC
Inline Coconut Carbon Post Filter
On MyWaterClub.com you choose 1/4″ or 3/8″ tubing, and the price per filter drops when you buy more.
Where it goes
PAC is a post filter: it goes after the RO membrane, where it polishes the taste of the finished water. If you have a mineral or alkaline filter, PAC goes before it.
| Your setup | Order of stages |
|---|---|
| Countertop RO | Faucet adapter → sediment (SED) → pre-carbon (CAC) → RO membrane → post filter (PAC) → faucet |
| Countertop RO with DI | … → RO membrane → DI → post filter (PAC) → faucet |
| RO with a mineral or alkaline filter | … → RO membrane → post filter (PAC) → mineral or alkaline filter → faucet |
| Under-sink RO | Pre-filters → RO membrane → storage tank → post filter (PAC) → RO faucet |
| Fridge, ice maker or coffee maker line | Cold water line → sediment filter → PAC → appliance |
Placement rules
- Mineral and alkaline filters always go after this filter, never before. Carbon removes minerals too.
- Before the RO membrane in a countertop RO — use the CAC stage-2 filter there, so each filter carries the label for its position.
- With a DI filter — DI goes first, then PAC. TDS at the faucet reads a few ppm higher than right after the DI; that’s normal.
- Hot water lines — not for hot water. Cold water only, 36–100°F.
Connections
Before you cut anything
- Check your tubing size. It is either 1/4″ OD or 3/8″ OD, usually printed on the tubing. Use the matching adapters. Never force 1/4″ tubing into a 3/8″ port, or the reverse.
- Water must flow the way the arrow on the label points — toward the faucet.
- You need a tubing cutter (or a sharp utility knife), a towel and a small bucket.
- 1/4″ tubing goes straight into the filter’s quick-connect ports. For 3/8″ tubing, add a 3/8″ elbow adapter to each port first.
- Cut the tubing square. A cut off by about 15° or more will leak. The last inch should be round, smooth and free of scratches.
- Remove any blue C-clips from the adapters. A clip left in stops the tube from seating.
- Push the tube in until it stops, then pull gently to confirm it holds.
- Refit the blue C-clips on every quick-connect port.
To remove a tube later: turn off the water and release pressure, take off the C-clip, push the collar in toward the filter and pull the tube out while holding the collar.
Replacing it in a countertop RO
- Turn off the faucet and disconnect the faucet adapter. Open the RO tap to release pressure.
- Take photos of the system from both sides before you remove anything, so the tubing and the flow arrows are visible.
- Hold a towel under the filter, release both tubes and take out the old post filter.
- Put in the new PAC filter with the flow arrow pointing toward the faucet. Push both tubes in until they stop, tug to check, and refit the C-clips.
- Reconnect the faucet adapter and turn the water on slowly. Check for leaks now, after 10 minutes, and the next day.
- Flush for at least 5 minutes before drinking the water. Grey water or a few black specks at first are carbon dust from a new filter — that’s normal.
- Write the install date on the label.
Adding it to an under-sink RO
First time? Watching a short video helps: search YouTube for “add inline filter to RO system”.
- Shut off the RO water supply and the tank valve, then open the RO faucet to release pressure.
- Find the spot: after the storage tank, before the RO faucet — and before any mineral or alkaline filter.
- Check the tubing size and that the adapters match, then cut the tubing square over a towel.
- Connect the filter with the flow arrow pointing toward the faucet, and refit the C-clips.
- Secure the filter with a clip: a 2.5″ × 2″ clip onto the membrane housing, or a 2″ × 2″ clip onto another inline filter.
- Open the supply and tank valves. Check for leaks now, after 10 minutes, and the next day.
- Flush for at least 5 minutes with the RO faucet open. Let the tank fill, then discard the first full tank.
- Write the install date on the label.
When to change your filter
| Filter | Typical interval | Change sooner if… |
|---|---|---|
| Coconut carbon post filter (PAC) | 12 months or 1,500 gallons |
A stale, flat or plastic taste comes back, or flow drops |
A TDS meter won’t tell you when to change a carbon filter — carbon doesn’t change dissolved solids. Go by the calendar and the taste. Most people change it at the same yearly service as the sediment and stage-2 filters.
Parts that fit this filter
| Part | Notes |
|---|---|
| Pre-carbon filter, stage 2 (CAC-QC) | Before the RO membrane |
| 5 micron sediment filter (SED5-QC) | Stage 1 |
| Alkaline filter (ALC-QC) | Optional last stage, right after this filter |
| 1/4″ stem × 3/8″ quick-connect elbow, 2-pack | Adapters for 3/8″ tubing |
| Blue C-clips for 1/4″, 10-pack | Locks the tube in a 1/4″ port · clips for 3/8″ elbows |
| 2.5″ × 2″ mounting clips, 2-pack | Clips the filter onto an RO membrane housing · 2″ × 2″ clips |
| 1/4″ OD tubing, white | If you need extra length · tubing cutter |
Common questions
| What you’re seeing | Most likely cause |
|---|---|
| Grey water or black specks right after a change | Carbon dust from a new filter. Flush for at least 5 minutes; it clears quickly. |
| Stale, flat or plastic taste came back | The carbon is used up. Replace the PAC filter. |
| TDS at the faucet is a few ppm higher than right after the DI | Normal. A carbon post filter adds about 2–6 ppm. |
| TDS reading didn’t change after the new filter | Expected. Carbon doesn’t reduce dissolved solids — the RO membrane does that. |
| Low flow | Filter installed backward, kinked tubing, or an RO membrane due for a change. Check the arrow and the tubing first. |
| Drip at a quick-connect port | Tube not fully in, scratched or cut at an angle, or the C-clip was left in. Release, recut square, push it fully in and refit the clip. |
Need help?
Contact us
Send a photo of the filter label and your system, and we’ll tell you where it goes
Call or text (858) 345-7345. Bought on Amazon? You can also reach us through Amazon: Your Orders › Contact seller.
Scope note: This is an activated carbon post filter. It reduces taste, odor and chlorine. It does not reduce fluoride, hardness or dissolved solids, and it is not a certified microbiological purifier. Use it on municipally treated or otherwise microbiologically safe water.
Please note: Filter life depends on your water quality, pressure and usage, so results vary from home to home. This product is not certified to treat water of unknown quality and is not a substitute for testing your water.