Short answer: public water systems add chlorine, or chloramine (chlorine plus ammonia), to keep water free of bacteria on its way through miles of pipe. Both are regulated to safe levels. By the time water reaches your home the disinfectant has done its job, and a point-of-entry filter can reduce its taste and odor at every tap. Chloramine is harder to reduce than free chlorine, so the media matters, and so does knowing which one your town uses.
Why towns disinfect
Treating water at the plant is only half the job; it has to stay safe in the distribution system. A residual disinfectant in the pipes prevents regrowth of bacteria between the plant and your tap. The U.S. EPA sets a maximum residual disinfectant level of 4 mg/L (as chlorine) for both chlorine and chloramine, and systems are required to maintain a detectable residual. Puronics notes that typical residential levels are 0.5 to 1 ppm.
Chlorine versus chloramine
| Free chlorine | Chloramine (monochloramine) | |
|---|---|---|
| What it is | Chlorine gas or hypochlorite dissolved in water | Chlorine combined with ammonia |
| Why systems use it | Strong, fast-acting, long track record | Longer-lasting residual in large systems; forms fewer regulated disinfection by-products |
| Taste and odor | Noticeable "pool" smell, especially in hot showers | Milder odor but persistent; harder to remove |
| Reduction at home | Standard activated carbon works well | Needs catalytic carbon or specialized media with enough contact time |
| Fish and dialysis | Must be removed from aquarium water | Must be removed; standard dechlorinators may not work. Dialysis facilities remove it specifically |
| Plumbing | Mildly oxidizing | Puronics and others note chloramine is corrosive to lead and copper plumbing and some rubber components |
A municipality may use one, the other, or switch seasonally. The choice is published in the system's annual water quality report (Consumer Confidence Report), which every public water system in New York must provide to customers each year.
Why it matters to the treatment choice
Ordinary carbon filters that handle chlorine comfortably can let chloramine through. The Puronics C-series systems we install use ChloroShield Clearess media with what Puronics calls Chlorostatic technology, designed to reduce both chlorine and chloramine at every tap. The chlorine taste-and-odor claim is certified under NSF/ANSI 42; chloramine reduction is a manufacturer performance claim, and we describe it that way. The media is rated for up to 2,600,000 gallons of municipal water at normal flow, based on testing at 2.0 ppm chlorine and extrapolated for typical levels; higher disinfectant levels shorten media life. Details on the whole-house filtration page.
What filtration will and will not change
- Will change: the chlorine smell in showers and at the tap; the drying effect of disinfectant on skin and hair; fading of laundry; the taste of water used for cooking and coffee throughout the house.
- Will not change: the safety of the water, which was established at the plant. Removing the residual at the point of entry does not reintroduce bacteria into a sound household plumbing system, but it also does not make water that was unsafe become safe.
- Separate question: dissolved contaminants in drinking water (lead from household plumbing, PFOA/PFOS, arsenic, nitrate). Those are reverse-osmosis questions, answered by lab results. See reverse osmosis.
No alarm intended
This guide describes taste, odor, skin, laundry and plumbing effects. We do not make health claims about chlorine or chloramine at regulated levels; both are used because they prevent waterborne disease. If you have a specific medical reason to avoid a disinfectant (dialysis at home, for example), talk with your physician and your water utility.
One town’s report is not the county’s
Our service area contains dozens of separate public water systems and many thousands of private wells. Saratoga Springs, Clifton Park, Glens Falls, Schenectady and Troy each run or buy from different sources with different treatment, and the villages in between run small systems of their own. A report from one of them tells you nothing about the house two miles away on a well, or about a neighboring village on a different source. That is why we check your provider's report and measure the residual at your own tap during the in-home assessment instead of assuming from the county you live in.
How to find your town’s report
- Look for "annual water quality report" or "Consumer Confidence Report" on your town, village or city website, or on your water bill.
- Find the section on disinfection or disinfectant residual. It will name chlorine or chloramine and give the range measured.
- Bring it to the assessment, or send it with your request. It shortens the conversation.