CTO Carbon Block Filter is a type of activated-carbon water filter. CTO stands for Chlorine, Taste and Odour, which describes its main purpose. It is made by compressing activated carbon into a solid block rather than using loose carbon granules.
What it does
A CTO carbon block can help reduce:
-
Chlorine from municipal water
- Bad tastes and odours
- Certain organic compounds and VOCs
- Some fine sediment/particles, depending on its micron rating
- Some specific contaminants such as certain heavy metals, but this depends on the particular carbon and manufacturer's specifications.
The carbon works mainly through adsorption: contaminants attach to the enormous internal surface area of the activated carbon. The solid block also forces water through the carbon rather than allowing water to easily channel through loose granules.
CTO vs your 100% coconut post-carbon filter
The important difference is that "CTO" describes the function, while "100% coconut carbon" describes the carbon material.
So you can actually have a 100% coconut-shell CTO carbon block. Some manufacturers specifically make CTO blocks from activated coconut-shell carbon.
| Filter |
Main purpose |
| Coconut-shell post carbon |
Final polishing, taste and odour improvement |
| CTO carbon block |
Chlorine, taste, odour + finer carbon filtration |
| Sediment filter |
Dirt, sand, rust and particles |
| RO membrane |
TDS, salts and many dissolved contaminants |
For an RO system
A CTO carbon block is particularly useful before the RO membrane, because chlorine can damage certain RO membranes. It can therefore act as a protective carbon stage before the membrane.
It can also be used after RO as a polishing stage, depending on the system design.
One important point
Don't assume that a CTO filter makes unsafe water safe to drink. A standard carbon block is not a microbiological sterilisation system and does not automatically remove bacteria and viruses.
