Carbon removes chlorine, and that much is not in dispute. The useful question is how completely, because the answer is set almost entirely by engineering rather than by chemistry: how much carbon the water passes through, how long it is in contact with it, and whether the media has been treated for the specific job.
Contact time is the whole variable
Chlorine removal happens as a surface reaction, and reactions need time. The industry measures this as empty bed contact time, which is simply the bed volume divided by the flow rate through it. A large whole house tank at normal household flow gives many seconds of contact and removes chlorine essentially completely. A carbon block in a cartridge gives less and removes most of it. A pitcher or faucet unit gives a fraction of a second and takes out enough to fix the taste while leaving a good deal of the load in the water.
Free chlorine against chloramine
The two are not equivalent duties. Free chlorine reacts readily at a carbon surface. Chloramine, chlorine bonded with ammonia, is deliberately more stable so that a residual survives to the far end of a distribution network, and standard carbon needs several times the contact to break it down. Catalytic carbon, surface treated to accelerate that specific reaction, is the correct media where chloramine is used, and fitting standard carbon against chloramine is the most common reason a system underperforms its specification.
The bed is consumed, invisibly
Unlike taste and odor adsorption, chlorine removal chemically consumes the carbon, so a bed has a finite chlorine capacity set by the total volume that has passed through it. That capacity expires with no visible sign: the water does not discolor and often does not taste of chlorine immediately, because the last of the bed still handles the taste threshold after it has stopped removing the bulk. Change on the manufacturer's stated volume, or test the outlet with a chlorine test, rather than relying on the taste of the water.
Matching format to purpose
If the goal is whole house chlorine removal, protecting a softener's resin, hoses, seals and skin, that is a backwashing carbon tank sized to peak flow, and nothing smaller does it. If the goal is drinking water, a carbon block under the sink is proportionate and effective. If the goal is simply a better tasting glass, a pitcher does the job it is sold for. Our whole house filter cost guide covers sizing a carbon bed properly, which is where most underperforming systems go wrong.
Questions people ask about does carbon filter remove chlorine
Does carbon remove chlorine completely?
A properly sized whole house bed does. Smaller formats remove progressively less, because contact time falls with bed volume.
What is empty bed contact time?
The bed volume divided by the flow rate through it. It is the number that determines how completely chlorine is removed.
Is standard carbon enough for chloramine?
Usually not. Chloramine is deliberately more stable and needs catalytic carbon or several times the contact time of free chlorine.
How do I know when the carbon is spent?
Not by taste. Chlorine removal consumes the media invisibly. Change on the stated volume or test the outlet with a chlorine test.