Catalytic vs Standard Carbon for Chloramine in NC
Raleigh Water Pros • September 20, 2026 • 11 min read
Most national guides to catalytic carbon end at the same instruction: check your utility’s annual report, find out which disinfectant it uses, and buy accordingly. That is correct advice and it is also homework, which is why a lot of people close the tab and buy whatever the salesperson brought.
We read the annual water quality report for twenty-one North Carolina city systems and wrote the answer down. Nine of them carry a chloramine residual and twelve carry free chlorine, and that one difference decides whether standard activated carbon or catalytic carbon belongs in your tank. Choose wrong and you own a filter that looked right on the quote and disappoints at the sink.
Below: what chlorine and chloramine actually are, why standard carbon handles one easily and struggles with the other, how contact time and tank size change the answer, and a table of North Carolina utilities so you can find your own city, plus what to do if yours is not in it.
What is the difference between chlorine and chloramine?
Chloramine is chlorine with a small dose of ammonia added to it, and that one change makes it far more stable inside a water main.
Free chlorine is the fast, aggressive version. It disinfects hard and then fades, which is awkward in a system with thousands of miles of pipe between the plant and the last house on the line. So many utilities chlorinate at the plant, then add ammonia to form monochloramine, which holds its residual much further out.
Greensboro describes the sequence in its own words: chlorine “is the primary disinfectant used in the treatment process inside the plant”, while “chloramines are secondary disinfectants used in the distribution process”, formed by adding sodium hypochlorite and liquid ammonium sulfate to the finished water. New Bern’s report gives the reasoning: compared with free chlorine, chloramines “form fewer chemical by-products in the distribution system, improve taste and odor characteristics, and last longer in the distribution system to prevent bacterial growth.”
Both describe good engineering. The consequence lands at your tap: free chlorine gasses off if you leave a jug on the counter overnight and chloramine does not, which is why the old pitcher trick fails in Raleigh and works in Charlotte.
Does standard carbon remove chloramine?
Not at the speed a house runs water. Standard granular activated carbon strips free chlorine quickly and thoroughly. The reaction finishes in a fraction of the time the water spends inside the bed, so even a modest cartridge keeps up with a shower and a dishwasher running together.
Chloramine is built to resist exactly that kind of breakdown, because resisting breakdown is its job in the pipe. Against plain carbon the reaction is slow, and at household flow rates a good deal of it goes straight past the media.
Catalytic activated carbon is the same base material with its surface altered during manufacture so that it drives the chloramine reaction far faster. It is not a coating and not a different mineral: it is carbon tuned for a reaction plain carbon does slowly. That is the entire difference.
| Standard activated carbon | Catalytic activated carbon | |
|---|---|---|
| Free chlorine taste and smell | Handles it easily | Handles it easily |
| Chloramine | Slow; much of it passes at household flow | The media built for the job |
| Taste, odour and organics | Yes, behind a prefilter | Yes, behind a prefilter |
| Right for | Systems reporting a chlorine residual | Systems reporting a chloramine residual |
Want the answer for your own address rather than your city’s average? Request a free consultation and we test your water first, then quote in writing.
Why tank size and contact time decide the outcome
Media only works while water is touching it. The number that matters is how many seconds each gallon spends inside the carbon bed, and that falls as flow rises. A shower alone is gentle. A shower, a washing machine and an irrigation zone at once is not.
Free chlorine forgives a short contact time because the reaction is fast. Chloramine does not. That is why two houses can buy the same bag of catalytic carbon and get different results: the one with the larger tank and the correctly sized bed gets the contact time the reaction needs, and the one sized to a brochure figure does not.
So the sizing conversation in a chloraminated city is not really about the media. It is about your peak flow, the fixtures that realistically run together, and whether the tank backwashes often enough to stop the bed channelling. Ask for those three numbers on any quote for carbon filtration, and treat a quote naming a media type but no bed size as unfinished.
Pro tip: Raleigh Water converts the whole system to free chlorine for about five weeks every late winter, published in its own monthly report as 26 February to 2 April for 2026. Standard carbon would cope for those five weeks and fall behind for the other forty-seven, which is why catalytic is the year-round specification here rather than a seasonal one. More in Raleigh’s annual chlorine switch.
Which North Carolina cities use chloramine?
Nine of the twenty-one city systems we read carry a chloramine residual: Raleigh, Greensboro, High Point, Burlington, Monroe, Fayetteville, Greenville, New Bern and Southern Pines. Every figure below is the utility’s own published residual.
Chloramine systems. Specify catalytic carbon.
| City system | What its own report shows | Carbon to specify |
|---|---|---|
| Raleigh Water (also Garner, Wake Forest, Rolesville, Knightdale, Wendell, Zebulon) | Chloramines 2.80 ppm, ammonia fed at both plants | Catalytic |
| Greensboro | Chloramines 2.1 ppm, monochloramine described in the city’s own wording | Catalytic |
| High Point | Chloramines 2.55 ppm; switched from chlorination in early summer 2011 | Catalytic |
| Burlington | Chloramines 2.31 ppm; converted in July 2011 | Catalytic |
| Monroe | Chloramines 3.04 ppm; “chlorine and ammonia are added to disinfect the water” | Catalytic |
| Fayetteville (PWC) | Chloramination named outright as the main disinfectant | Catalytic |
| Greenville (GUC) | Chloramines 2.75 ppm, named as the secondary disinfectant | Catalytic |
| New Bern | Chloramines 2.96 ppm; began using chloramines June 2010 | Catalytic |
| Southern Pines | Chloramine residual 2.35 ppm in the compliance table, but the report never names a primary disinfectant. Inferred, not stated. | Catalytic, after a call to the town |
Free chlorine systems. Standard carbon is appropriate.
| City system | What its own report shows | Carbon to specify |
|---|---|---|
| Charlotte | Chlorine 1.04 ppm; the residual line reads Chlorine, not Chloramines | Standard |
| Huntersville | Charlotte Water serves it; the same 1.04 ppm figure applies | Standard |
| Concord | Chlorine 1.06 ppm | Standard |
| Gastonia | Chlorine 1.2 ppm | Standard |
| Mooresville | Chlorine 1.43 ppm; no chloramines row anywhere in the report | Standard |
| Winston-Salem | Chlorine 1.02 ppm, and the words chloramine and ammonia appear nowhere in the 2024 or 2025 report. Inferred, not stated. | Standard, after a call to the utility |
| Asheville | Chlorine 1.21 ppm, with ozone also used at the Mills River plant | Standard |
| Hendersonville | Chlorine 1.4 ppm, no ammonia feed anywhere in the process | Standard |
| Hickory | One disinfectant row, Chlorine, in the 2024 report | Standard |
| Wilmington (CFPUA) | Chlorine, alongside UV and ozonation at the Sweeney plant | Standard |
| Leland (H2GO) | Chlorine, roughly 0.80 ppm leaving the plant | Standard |
| Jacksonville | Chlorine 0.82 ppm | Standard |
Two rows are marked inferred on purpose. Winston-Salem reports a chlorine residual and never mentions chloramination, which points strongly to free chlorine without saying so outright. Southern Pines publishes a chloramine residual but names no primary disinfectant. Both are almost certainly what the table says, and neither is confirmed in the utility’s own words, so make the call first.
The full city-by-city reading sits in our North Carolina water quality guide, and the city water treatment page covers what we install on each type.
What if your utility is not in the table?
Two ways to get the answer, and both are free. The first is a phone call to your water utility with one question: does the system carry a chloramine residual or a free chlorine residual? Any operator answers that in a sentence. Durham is one of the systems outside the table, and our Durham water treatment cost guide covers its disinfectant and what catalytic carbon costs there.
The second is your Consumer Confidence Report. Every community water system in North Carolina publishes one each year, and the state’s report template requires a chloraminated system to report on the Chloramines line. Find the disinfectant residuals table and read the label:
- The row reads Chloramines, you are chloraminated. Catalytic carbon.
- The row reads only Chlorine, you are on free chlorine. Standard carbon does the job.
- Both rows appear. That is normal for a chloraminated system that converts to free chlorine for a few weeks a year. The averages alone will not tell you which is the year-round residual, so do not infer it from whichever number is higher: read the utility’s description of its own treatment process, and look for its changeover notice, which is where the practice is actually stated. On Raleigh Water both are published.
One trap worth knowing: the byproduct table in most reports attributes trihalomethanes to “by-product of drinking water chlorination”. That wording is federal boilerplate printed in every report in the country, chloraminated or not. Only the residual row tells you about your plant.
Frequently Asked Questions
Does a standard carbon filter remove any chloramine?
It removes some, just slowly. Standard granular activated carbon and chloramine do react, but not fast enough to finish inside the seconds a household flow rate allows, so the result at the fixture is partial reduction rather than the clean removal people expect. That is the gap catalytic carbon closes.
Is catalytic carbon more expensive than standard carbon?
The media costs more per cubic foot, but the installed system lands in the same band: a whole house carbon filter runs $1,500 to $3,500 installed either way, because the tank, valve, bypass and labour dominate the price. Our Raleigh cost guide breaks down what moves that figure. Treat any number here as a planning range, never a quote.
Does reverse osmosis remove chloramine?
The carbon stage in front of the membrane does that work, not the membrane itself, which is why a drinking water system’s prefilters matter as much as its cartridge count in a chloraminated city like Raleigh or Wake Forest. Our comparison of reverse osmosis and whole house filtration covers where each one belongs.
Does Raleigh use chlorine or chloramine?
Chloramine, year round, with one published exception: Raleigh Water converts to free chlorine for about five weeks each late winter. The 2026 window ran 26 February to 2 April. That is also true for Garner, Wake Forest, Rolesville, Knightdale, Wendell and Zebulon, which are inside the same public water system rather than separate utilities.
Do I need catalytic carbon on a private well?
Usually not for the chloramine reason, because a private well carries no disinfectant residual to remove. Most well carbon is sized for taste, odour and organics, and it usually sits behind iron, sulfur or pH treatment.
There are two real exceptions worth knowing before you rule it out. Catalytic carbon is also used against hydrogen sulfide, the rotten-egg gas, where its catalytic action does work standard carbon does not, so a well with a sulfur problem is a genuine application. And some wells run a chlorine injection system ahead of the treatment train, which puts a disinfectant residual into the water that then has to come back out downstream. In both cases the media choice follows the water chemistry, which is another reason the decision comes after a test rather than before one.
How do I find out what is at my own tap?
Start with your utility’s annual report for the citywide picture, then test at the fixture for your own number, because a citywide average describes the whole distribution system, not your kitchen sink.
Sources
Every disinfectant figure above comes from the utility’s own annual water quality report, read in September 2026. Reports update yearly, so confirm the current one before buying media.
- Raleigh Water reports index, for Raleigh’s chloramine residual, ammonia feed and burnout dates.
- Charlotte Water quality report, for Charlotte and Huntersville.
- City of Greensboro water quality report and City of High Point chloramines page.
- Greenville Utilities water quality report and City of New Bern annual water report.
- EPA’s guide to Consumer Confidence Reports, for how to find and read your own.
Getting the carbon right in Raleigh and the Triangle
If you are on Raleigh Water in Raleigh, Garner, Wake Forest or Knightdale, the media answer is catalytic and the real work is sizing the tank to your peak flow. If you are on another Triangle system, the phone call above settles it before anybody quotes you.
We install and size whole house filtration across Raleigh, Cary, Apex, Garner and Durham. Call (984) 384-6991 or book a free consultation, and you get a written price with the media type and the bed size on it, not just a brand name.
