Journal / Water knowledge
Chlorine, chloramine and your water
Start with your supplier, then match the claim to the substance.
Both have a purpose.
Utilities use disinfectants to control germs as water is treated and distributed. Chlorine and chloramine are different disinfectants; monochloramine is the chloramine used in drinking-water treatment.
Why utilities use a disinfectant residual.
Treatment controls germs at the plant; a disinfectant residual continues to protect water as it travels through the distribution network. CDC explains that chloramine can remain active longer than chlorine, which helps it reach farther through pipes.
That is why the disinfectant belongs in a home filtration discussion. Start with what your own supplier uses, then look for a filter claim that names that substance.
Read the names precisely.
A report may express a disinfectant concentration “as chlorine.” Keep the full row label and its notes: the unit convention does not by itself tell you which disinfectant is present.
| Label | What it refers to |
|---|---|
| Chlorine | A disinfectant used in water treatment. |
| Monochloramine | The chloramine used for drinking-water disinfection. |
| Free chlorine claim | A filter claim about free chlorine under specified conditions. |
| Chloramine claim | A separate claim to look for when the supply uses chloramine. |
Keep taste and treatment questions separate.
Describe a taste or odor change to the supplier, including when it started and whether it appears at more than one tap. Compare the current notice with the annual report, which describes an earlier reporting period.
For a product comparison, bring the disinfectant name, the incoming-water information and the intended outlet. Drinking water and shower water have different use patterns, temperatures and flow requirements.
Ask your own supplier.
Do not infer the disinfectant from the name of a nearby city or from a general national trend. Read your supplier’s current report and notices. The information that matters is the treatment used for your service area.
If taste or odor has changed, describe the change to your water supplier. A new taste alone is not enough to identify a substance or determine its concentration.
Make the filter claim match.
Look for a named reduction claim for the substance you want to address. A product tested for free chlorine is not automatically tested for chloramine.
NSF’s certification resources let you check specific models and their reduction claims. Keep the exact cartridge and operating conditions with the comparison.
Keep care part of the routine.
Read the installation and care instructions, use the specified replacement and follow its service interval. Keep the cartridge reference and installation date with your product documents.