Chloramine is chlorine bound with ammonia, used by many utilities because it is far more stable than free chlorine and persists all the way to the tap. That stability is exactly the property that defeats ordinary filtration. A carbon cartridge sized and specified for chlorine will reduce chloramine slowly and partially, which is why so many households conclude their filter has failed when it is simply the wrong specification.
Establish that chloramine is what you have
This is free and takes minutes. The EPA notes that every community water system publishes an annual Consumer Confidence Report and maintains a finder for them, and the report names the disinfectant in use. Some systems run chloramine most of the year and switch to free chlorine for a short burn, which is why a filter can seem to work in spring and not in summer. Establish the answer before buying, because the difference between the two disinfectants changes the equipment, the size and the price.
Catalytic carbon is the media that works
Standard activated carbon reduces free chlorine through a fast surface reaction. Chloramine reduction is a different, slower chemistry, and the media made for it is catalytic carbon, whose surface has been modified specifically to drive that reaction. It is not a marketing grade: it behaves measurably differently. When comparing products, look for catalytic carbon named in the specification and for a chloramine reduction claim, rather than assuming that more stages or a bigger housing achieves the same thing.
Contact time is the other half
Even with the right media, chloramine needs the water to spend meaningfully longer in contact with the carbon than chlorine does. In practice that means a larger bed or a slower flow. A whole house unit sized on a chlorine rating will under perform on a chloraminated supply at the same flow, which is the single most common installation error here. At the point of use it means preferring a larger cartridge over a small one, and it is a reason a slower filter can outperform a faster one on the same water.
The alternatives, and where they fit
Reverse osmosis systems handle chloramine, though the carbon prefilter is doing much of that work and protecting the membrane while it does. Ascorbic acid neutralizes chloramine chemically and is used in some shower filters and in dechlorination products for ponds and aquariums. Boiling and standing, which work on free chlorine, do very little here. If the aim is to stop the smell in the shower as well as improve drinking water, a point of entry unit correctly sized for chloramine is the answer. Our replacement filter guide covers matching cartridges.
Questions people ask about chloramine filters
Why does my carbon filter not remove chloramine?
Standard carbon reduces it slowly and incompletely. Chloramine needs catalytic carbon and substantially longer contact time than free chlorine does.
How do I find out if my water is chloraminated?
Your utility's annual Consumer Confidence Report names the disinfectant, and the EPA maintains a finder for those reports.
Does boiling remove chloramine?
Very little. Unlike free chlorine, chloramine is stable and does not readily dissipate with boiling or standing.
Does reverse osmosis deal with it?
The system does, though the carbon prefilter is doing most of that work and is also protecting the membrane, which chloramine and chlorine both damage.