FIELD NOTES · HOME WATER
Chlorine vs. Chloramine: Why Your Filter Probably Misses It
This is the single most common mistake I see people make with home water: buying a carbon filter that was never designed to remove what their city actually puts in the water. The fix starts with knowing the difference between chlorine and chloramine.
Why cities switched to chloramine
For decades, utilities disinfected water with chlorine. Many have since switched to chloramine — chlorine combined with ammonia — because it's more stable and lingers longer in the pipes, which helps keep water safe over long distribution networks. From a public-health standpoint, that's a reasonable trade-off.
From a home-filtration standpoint, it's a problem, because chloramine behaves very differently from chlorine when it hits a carbon filter. The disinfectant that's easiest for a city to manage is one of the harder ones for a homeowner to remove.
Why ordinary carbon struggles with it
Standard activated carbon — the media in most pitchers, fridge filters, and budget whole-house cartridges — adsorbs chlorine quickly and effectively. With chloramine, that same carbon works far more slowly and far less completely. Water often moves through the filter faster than the carbon can break the chloramine down, so a chunk of it sails right through.
The result is people who think they're filtering their water but are really only filtering part of it. The taste improves a little, so they assume it's working — while the chloramine is largely still there.
Catalytic carbon is the real answer
Catalytic carbon is processed specifically to accelerate the reaction that breaks chloramine apart. It's the media I use in the second tank of my own system precisely because my city uses chloramine. If your water has chloramine, this is the difference between a filter that works and one that just looks like it does.
It costs more than standard carbon and you need enough of it (contact time matters), which is part of why I run a dedicated tank rather than a small cartridge. A tiny inline cartridge simply can't give the water enough seconds in contact with the media to do the job, no matter what the box claims.
A quick reality check on “removes chlorine” labels
Be skeptical of packaging that proudly says “removes chlorine” when your problem is chloramine. Technically the claim may be true and completely beside the point for your water. Manufacturers know “chlorine” is the word shoppers recognize, so it ends up on the box even when the media inside is poorly suited to the ammonia-bound version your city actually uses. Read for the specific word “chloramine,” and if it isn't there, assume the product wasn't built for it.
How to find out what your city uses
You don't have to guess. Every U.S. water utility publishes an annual water-quality report (sometimes called a Consumer Confidence Report). Pull yours and search it for the word "chloramine." You can also confirm with a test strip designed to distinguish total chlorine. If chloramine is in there, skip the generic carbon filter and go straight to catalytic carbon — I walk through reading that report in a separate guide.
Common questions
Why does standard carbon remove chlorine but not chloramine?
Standard activated carbon adsorbs chlorine quickly and effectively, but it reacts with chloramine far more slowly and less completely. Water usually moves through the filter faster than the carbon can break the chloramine down, so a chunk of it passes right through. The taste improves slightly, which fools people into thinking the filter is working.
How can I find out whether my city uses chlorine or chloramine?
Every U.S. water utility publishes an annual water-quality report, sometimes called a Consumer Confidence Report. Pull yours and search it for the word chloramine. You can also confirm with a test strip designed to distinguish total chlorine.
What actually removes chloramine from home water?
Catalytic carbon is processed specifically to accelerate the reaction that breaks chloramine apart, so it is the real answer when your city uses chloramine. It costs more than standard carbon and needs enough contact time to work, which is why a dedicated tank beats a tiny inline cartridge. A small cartridge simply cannot give the water enough seconds in contact with the media.
Can I trust a filter that says it removes chlorine?
Be skeptical when the label says removes chlorine but your real problem is chloramine, because the claim can be technically true and still beside the point for your water. Manufacturers use the word chlorine because shoppers recognize it, even when the media inside is poorly suited to the ammonia-bound version. Look for the specific word chloramine, and if it is not there, assume the product was not built for it.