Activated Carbon and Treated Carbon: What They Do Inside a Filtration System

Carbon shows up in pitchers, faucet filters, and reverse osmosis systems. Sometimes it's described as activated, other times as treated or catalytic.

It's easy to assume all of those terms mean the same thing. To understand what you're buying, it helps to know what each one describes.

What "activated" means

Activated carbon is a material that has been processed to develop a porous structure with a large internal surface area. It can be made from different raw materials, such as coconut shell, wood, or coal.

That structure allows for adsorption: certain substances adhere to its surface. Its capacity depends on the properties of the material and on the substances present in the water. Source: EPA

That's why what the carbon is made from is a product feature, but it isn't enough to prove how well it performs.

And what does "treated carbon" mean?

The term needs an explanation from the manufacturer. On its own, it doesn't point to any specific reduction capability.

When you come across it, ask:

• What treatment did the carbon receive?
• What function was it applied for?
• What testing backs up that function?
• Does the evidence apply to the material or to the complete cartridge?

That last distinction matters. The performance of a material tested on its own doesn't automatically describe the performance of the system installed in your home.

The case of catalytic carbon

Catalytic carbon has characteristics that promote certain reactions. It's used, for example, in chloramine reduction applications.

Calgon Carbon explains that its catalytic carbons can provide faster reactions than conventional carbons in specific applications. That benefit has to be carried over to each product through its design and testing, not assumed for just any cartridge. Source: Calgon Carbon

If your water provider uses chloramine, ask about that specific reduction. A claim for free chlorine doesn't necessarily address the same need.

What role it plays before a membrane

In some reverse osmosis systems, carbon helps reduce chlorine before the water reaches the membrane.

This can protect membranes that are sensitive to oxidants. DuPont, for example, states that its FilmTec membranes require free chlorine to be controlled through pretreatment to prevent damage. Source: DuPont

It's an example of how the stages complement each other. The prefilter can also contribute to how the system as a whole works.

Capacity and maintenance

Carbon doesn't keep its capacity indefinitely. Contact time, flow rate, the substances present, and the design all affect performance. Once its capacity is used up, it needs to be replaced or given the treatment intended for that application. Source: EPA

In a home system, follow the replacement instructions. Don't assume that washing it restores its performance.

A better question to ask when you buy

Instead of stopping at "does it have carbon?", ask: "what does this cartridge do in this system, and how has that been verified?"

At PFC, we want you to be able to understand the role of each component and maintain it properly throughout its use.

Free your water with PFC.

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