Why Most Carbon Water Filters Can’t Remove Chloramine in Canadian Tap Water

For years, most Canadians figured any carbon water filter—a pitcher, fridge cartridge, or simple under-sink unit—was enough to make their tap water safe from disinfectant chemicals. That was mostly true, since cities used chlorine, which standard carbon filters remove pretty well. But now, many Canadian water suppliers are switching to chloramine, which behaves very differently in water and in filters. This change means that many “chlorine filters” can’t really do the job anymore. If you want to remove these new chemicals properly, you need a real chloramine filter.

Why Canadian Cities Are Switching to Chloramine

Chloramine is made by mixing chlorine with a little ammonia. Water utilities like it because it stays in the water much longer than just chlorine. While chlorine disappears quickly and reacts with things in the pipes, chloramine hangs around, providing better protection against bacteria, especially in large or older water networks.

There's also a public health driver behind the switch. Chlorine reacts with natural organic matter in source water to form disinfection by-products (DBPs) such as trihalomethanes, compounds that regulators have linked to elevated cancer risk. As a peer-reviewed environmental health study explains, growing concern over these chlorination by-products led U.S. and Canadian regulators to tighten limits on them, which in turn pushed an increasing number of municipal water systems toward chloramine as an alternative disinfectant that produces far fewer of these by-products.

Now, many Canadian cities—including large ones in Ontario and other provinces—use chloramine as their main disinfectant. For you, this means the water at your tap is different from what your parents had. And it means you need a carbon water filter made to handle chloramine—a true chloramine filter—to keep your water safe at home.

Why Standard Carbon Filters Fail to Remove Chloramine

To see why standard carbon filters have trouble with chloramine, it helps to know how carbon filters work with chlorine. Regular granular or block activated carbon removes chlorine quickly, thanks to a fast chemical reaction at the surface of the carbon. The chlorine molecules react almost instantly with the carbon and are neutralized on contact.

Chloramine doesn't behave the same way. Because the chlorine atom in chloramine is already bonded to ammonia, the molecule is more stable and far less reactive. It resists the same simple surface reaction that destroys free chlorine so efficiently. Industry water-treatment literature on activated carbon dechlorination notes that chloramine molecules are small, largely non-ionic, and chemically stable — properties that make them resistant not just to standard carbon filtration, but also to reverse osmosis membranes, water softening, boiling, and distillation, none of which reliably remove chloramine either.

The real-world result? A typical carbon water filter labeled for “chlorine, taste, and odor” might take out most of the chlorine but let a lot of chloramine slip right through. That’s because removing chloramine is a much slower process, and most household filters don’t keep water in contact with the carbon long enough. So, if you want to remove chloramine effectively, you need a dedicated chloramine filter—not just any carbon water filter.

How Catalytic Carbon Is Different

Catalytic carbon might look like regular activated carbon, but it’s made differently—and that difference is what makes it actually work on chloramine.

Catalytic carbon is typically produced by treating activated carbon at very high temperatures (up to roughly 750°C) in the presence of nitrogen-containing gases such as ammonia. This process strips away unreactive acidic oxide groups from the carbon's surface and replaces them with new, catalytically active carbon sites. According to technical analysis published by Water Conditioning & Purification magazine, the resulting nitrogen-doped surface doesn't simply adsorb chloramine the way ordinary carbon adsorbs many contaminants — it acts as a catalyst that chemically decomposes the chloramine molecule. In the proposed reaction pathway, active sites on the catalytic carbon convert chloramine into an intermediate carbon-oxide compound, which then further breaks the molecule down into harmless chloride ions, rather than trapping chlorinated compounds on the carbon surface where they could eventually saturate and break through.

Because this is a catalytic process rather than pure adsorption, the carbon isn't "used up" quite the same way a simple adsorption filter is — a much higher percentage of the surface area actively participates in destroying chloramine molecules. Fine-mesh catalytic carbon (much finer than the coarse granules used in ordinary filters) exposes dramatically more surface area to accelerate the reaction and increase overall capacity.

This is why water experts all agree: if you want to remove chloramine at home, you need a catalytic carbon water filter, not just any carbon filter. Water authorities across Canada—including Alberta, BC, and Ontario—are clear about this: only a catalytic carbon filter is truly effective for chloramine.

Where Unfiltered Chloramine Becomes An Issue

For the average person drinking, cooking with, and bathing in chloraminated tap water, the health risk from typical municipal chloramine levels is low — the U.S. EPA and Health Canada both permit its use as an approved residual disinfectant, and the digestive process neutralizes chloramine before it can enter the bloodstream through normal consumption. However, there are specific applications where chloramine exposure is not a minor inconvenience but a serious, sometimes life-threatening hazard:

Kidney dialysis. During hemodialysis, water is brought into direct contact with a patient's blood across a semi-permeable membrane, bypassing the digestive system's natural neutralizing process entirely. In this context, chloramine — like chlorine — is toxic if it enters the bloodstream directly. Dialysis facilities and home dialysis equipment must use pre-treatment systems specifically engineered to eliminate chloramine before water ever reaches the dialysis machine, and both regulatory guidance and industry standards require trained staff to routinely verify that this treatment is functioning correctly.

Fish, aquariums, and aquaculture. Fish and other aquatic animals absorb chloramine directly into their bloodstream through their gills. Once absorbed, chloramine reacts with hemoglobin to produce methemoglobin, a form of the molecule that cannot carry oxygen effectively — leaving fish gasping at the water surface even in a well-aerated tank. Unlike chlorine, which dissipates from standing water within a day or two, chloramine remains stable in water for weeks, meaning the old trick of "letting tap water sit out" before adding it to a tank does essentially nothing to protect fish. Aquarists, aquaculture operations, and businesses with lobster or fish tanks all need dedicated dechloramination, not just dechlorination.

Medical and laboratory uses. Any application where water contacts blood, tissue, or sensitive biological cultures — including some medical devices, wound irrigation in specific contexts, and laboratory work — requires chloramine-free water for the same reason dialysis does: the compound's toxicity is a bloodstream issue, not a digestive one.

Home brewing and food production. Chloramine imparts off-flavors and can react with organic compounds during brewing or fermentation to create medicinal or plastic-like taste defects that ordinary chlorine rarely causes at the same concentration, since chloramine does not boil off the way chlorine does.

In every one of these cases, the stability that makes chloramine attractive to municipal utilities — the very quality that lets it protect drinking water for weeks as it travels through the distribution system — is exactly what makes it so difficult to eliminate at the point of use without the right filtration media.

Chloramine, Gardening, and Sensitive Plants

For most outdoor garden beds and lawns, chloraminated tap water at typical municipal concentrations isn't a major concern — just as it isn't for drinking water. But two garden-adjacent situations deserve closer attention.

Soil biology and sensitive houseplants

Because chloramine doesn't dissipate the way chlorine does, it stays active in water much longer, which means it keeps disinfecting after it leaves the tap — including against the beneficial bacteria and fungi that live in potting soil and support root health. Standing tap water overnight, a common trick gardeners use to "let the chlorine evaporate off," does nothing for chloramine, essentially, since it doesn't off-gas the way free chlorine does. Repeated watering with chloraminated water can gradually suppress the microbial populations that support nutrient cycling in organic potting mixes, and several common houseplants — including calatheas, spider plants, and peace lilies — are frequently reported as chloramine-sensitive, showing root stress or leaf-tip browning over time with sustained exposure.

Hydroponics — where the risk is much more specific and better documented

Hydroponic systems remove soil from the equation entirely, which means plant roots sit in continuous direct contact with whatever is in the nutrient solution — including any residual chloramine in the source water. This is where the clearest scientific evidence of chloramine plant toxicity exists. A study published in the Journal of the Japanese Society for Horticultural Science, Induction of Root Browning by Chloramine in Lactuca sativa L. Grown in Hydroponics, investigated a common problem hydroponic growers encounter when nutrient solutions are prepared with tap water: a browning and breakdown of lettuce roots. The researchers found that root browning occurred only when both hypochlorous acid (the active form of chlorine) and ammonium ion were present together in the nutrient solution — not when either was present on its own — identifying chloramine, the reaction product of the two, as the specific cause. A related follow-up study on the same crop found that lettuce growth was measurably inhibited by chloramine exposure as brief as one hour at concentrations as low as 0.5 mg Cl/L, a level well within the range commonly found in municipally chloraminated tap water.

The practical takeaway for hydroponic growers, greenhouse operators, and anyone mixing nutrient solutions from municipal tap water: unlike garden soil, which buffers and dilutes disinfectant residuals to some degree, a recirculating hydroponic reservoir keeps roots in constant contact with whatever chloramine is present, making dechloramination of source water a meaningfully more important step than it is for conventional soil-based gardening.

Choosing an Effective Chloramine Filter: The PR110

Since removing chloramine requires catalytic carbon, and so many “carbon filters” on the market aren’t actually built for this job, choosing the right filter is more important than ever. If you want real chloramine protection, make sure your carbon water filter is actually a true chloramine filter with catalytic carbon.

One example of a filter engineered specifically around this problem is the PR110, a 10-inch under-sink catalytic carbon cartridge specifically designed to tackle chloramines. The PR110 is built around catalytic carbon derived from coconut shell carbon that has been modified at the electronic-structure level — the same category of surface modification described in the technical literature above — which increases adsorption capacity, speeds up the chloramine-destroying reaction, and extends the filter's usable lifespan compared to standard carbon.

A few design details make the PR110 particularly relevant to the chloramine problem specifically, rather than chlorine removal alone:

• It targets the ammonia by-product, not just the chloramine molecule.  When catalytic carbon breaks chloramine down, it leaves ammonia behind as a residual by-product. Many filters ignore this step entirely. The PR110 uses additional specialized media stages specifically to address that leftover ammonia, which is part of why treated water is described as odorless with noticeably improved taste, rather than simply "less chlorinated."
• It layers chloramine removal with heavy-metal reduction.  The cartridge combines catalytic carbon with redox media and molecular sieve minerals intended to address lead and other heavy metals in the same pass — relevant given that aging lead service lines remain a documented problem in many older Canadian homes.
• It's certified media (NSF/ANSI 42), not a generic carbon.  Because catalytic carbon's effectiveness depends heavily on its manufacturing process (mesh size, degree of nitrogen doping, surface treatment), independent certification is one of the few ways a consumer can distinguish a genuinely catalytic filter from a standard carbon cartridge marketed with catalytic-sounding language but without the underlying chemistry.

The Bottom Line

Chlorine and chloramine may both be called "disinfectant residuals," but as far as your home filtration system is concerned, they are two very different problems. Standard carbon filters — the kind built into most pitchers, fridges, and basic under-sink systems — were designed around chlorine's chemistry. That design does not translate to chloramine, a more stable molecule that resists simple adsorption and requires an actual catalytic reaction to break down. For most households drinking municipally chloraminated tap water, that gap mostly affects taste and odor. But for anyone running a home dialysis machine, keeping an aquarium, raising fish or growing lettuce, or brewing beer, an ineffective filter isn't a minor shortfall — it's the difference between safe water and a genuine hazard. Knowing whether your municipality uses chlorine or chloramine, and choosing a filter built with true catalytic carbon media rather than standard activated carbon, is the only reliable way to close that gap.