Chloramines can be removed from tap water, but the methods that work for free chlorine often fall short. The two most reliable approaches for home use are catalytic or granular activated carbon filtration and chemical neutralization with ascorbic acid (vitamin C). Each has trade-offs depending on whether you need treated water for drinking, bathing, aquariums, or medical use like kidney dialysis. Understanding why chloramines are stubborn compared to chlorine helps you pick the right solution and avoid wasting money on filters that won’t do the job.
Why Chloramines Are Harder to Remove Than Chlorine
Most municipal water systems use either free chlorine or chloramines to keep water disinfected as it travels through miles of pipes to your tap. Chloramines are formed by combining chlorine with ammonia, producing a more stable disinfectant that lasts longer in the distribution system. That stability is the whole point for your water utility, but it is also the reason chloramines are harder for you to get rid of at home.
Free chlorine is volatile. It escapes from water relatively quickly when exposed to air, which is why leaving a pitcher of chlorinated water on the counter overnight, or boiling it for a few minutes, can drive off most of the chlorine. Chloramines behave differently. Monochloramine, the form most commonly used in drinking water, has a much lower tendency to evaporate from water compared to free chlorine. Research measuring the volatility of various chlorine species found that at 40°C, monochloramine’s tendency to escape into the air was far lower than that of trichloramine or even hypochlorous acid, the active form of free chlorine.1Water Research. The fate of chlorine and chloramines in cooling towers Henry’s law constants for flashoff In practical terms, boiling or aerating your water will not meaningfully reduce monochloramine levels. It simply does not flash off the way free chlorine does.
This also means that the cheap carbon pitcher filters many people keep in their refrigerator are not reliable for chloramine removal. Those filters use small amounts of activated carbon with very short contact time. For free chlorine, that can be enough. For chloramines, the water needs to spend significantly more time in contact with a much larger bed of carbon to achieve real removal.
Granular Activated Carbon Filtration
Activated carbon is the workhorse technology for chloramine removal, and it is used everywhere from home under-sink filters to the massive systems that treat water for hospital dialysis units. The carbon does not simply trap chloramine molecules the way a sieve catches debris. Instead, it catalyzes a chemical reaction on the carbon surface that breaks the nitrogen-chlorine bond in monochloramine, converting it into harmless byproducts.
The catch is that this reaction requires adequate contact time between the water and the carbon. In the water treatment world, this is measured as “empty bed contact time,” essentially how long the water spends flowing through the carbon bed. Research on granular activated carbon for dialysis-grade water found that depending on the type of carbon used, anywhere from less than 8 minutes to as much as 20 minutes of contact time was needed to bring monochloramine down to the strict dialysis standard of 0.1 mg/L.2Journal AWWA. Monochloramine destruction by GAC—effect of activated carbon type and source water characteristics That is a long time for water to sit inside a filter, which is why small countertop or pitcher filters with a few tablespoons of carbon cannot do the job properly.
For home use, a whole-house or under-sink carbon filter rated specifically for chloramine removal is the practical choice. Look for filters that use catalytic carbon, a specially treated form of activated carbon designed to break down chloramines more efficiently than standard granular carbon. Standard activated carbon still works, but catalytic carbon can achieve the same removal with a smaller filter or faster flow rate, which matters when you are trying to fit a system under your kitchen sink. The key is ensuring the filter is sized for your actual flow rate. A filter rated for chloramine removal at 0.5 gallons per minute will not protect you if you are running water at 2 gallons per minute, because the water blows through too fast for the reaction to complete.
Carbon filters also have a finite life. The carbon surface gradually becomes less reactive over time, so replacement schedules matter. With the right type of carbon and adequate bed size, a well-maintained system can run for a long time at steady-state performance, but neglecting filter changes means chloramine eventually breaks through.
Vitamin C and Other Chemical Treatments
If you need a quick, no-equipment method, ascorbic acid (vitamin C) neutralizes chloramines through a chemical reduction reaction. This approach has been used for decades in medical settings. Research on dialysis water treatment confirms that chloramines can be neutralized by adding ascorbic acid directly to water, and that this method is a recognized alternative to carbon filtration in clinical contexts.3PubMed. Chloramine removal from water used in hemodialysis
For practical purposes, a small amount of ascorbic acid added to a bathtub or a bucket of water can dechloraminate it within minutes. This is popular among aquarium keepers and homebrewers, who need chloramine-free water but do not always want to invest in a dedicated filtration system. Sodium ascorbate works the same way and has the advantage of not lowering the water’s pH the way ascorbic acid does. The reaction is fast and relatively complete, though the exact dose depends on the chloramine concentration in your tap water, which varies by utility and by season.
Potassium metabisulfite and sodium thiosulfate are two other dechloraminating chemicals used in aquarium and brewing supply shops. They work well but are less intuitive for general household use. For bathing, vitamin C shower filters have become popular, and while the chemistry behind them is sound, the practical challenge is the same as with carbon filters: how much contact time the water actually gets with the dechloraminating agent as it flows through. A thin disc of vitamin C in a shower head dissolves quickly and may not last as long as advertised at high flow rates.
UV Light Treatment
Ultraviolet light can break down chloramines, but the practical picture is more complicated than it might seem. All three forms of inorganic chloramines, monochloramine, dichloramine, and trichloramine, are susceptible to UV photolysis, meaning UV light can break their nitrogen-chlorine bonds.4PubMed. UV photodegradation of inorganic chloramines The efficiency depends on the UV wavelength, with shorter wavelengths around 255 nm being more effective at breaking down monochloramine, while dichloramine actually degrades faster at longer wavelengths.5PubMed. UV Photolysis of Mono- and Dichloramine Using UV-LEDs as Radiation Sources: Photodecay Rates and Radical Concentrations
Trichloramine is the easiest of the three to destroy with UV, showing the fastest depletion rates in testing.6Water Research. Photolysis of inorganic chloramines and efficiency of trichloramine abatement by UV treatment of swimming pool water That is useful in swimming pool applications, where trichloramine is the main irritant that causes the harsh “chlorine smell” and eye-burning sensation. But for home drinking water, where monochloramine is the dominant species, UV treatment requires high UV doses that most residential point-of-use UV systems are not designed to deliver. Residential UV units are typically built to kill bacteria and parasites, not to photolyze chemical disinfectants, and the lamp intensity and exposure time needed for chloramine destruction are substantially greater than what is needed for microbial disinfection.
UV treatment is therefore better thought of as a supplementary or commercial-scale tool rather than a standalone home solution for chloramine removal. In pool and spa settings, medium-pressure UV systems are increasingly used to control trichloramine levels in the air and water, improving air quality for swimmers and staff. For home drinking water, carbon filtration remains the more practical choice.
What About Reverse Osmosis?
Reverse osmosis (RO) is one of the most thorough water purification methods available to homeowners, and many people assume it handles everything. For chloramines, the reality is less straightforward. Chloramines are not effectively removed by RO membranes alone.3PubMed. Chloramine removal from water used in hemodialysis The monochloramine molecule is small enough to pass through the membrane, and because it does not carry a strong charge at typical drinking water pH, the membrane’s charge-rejection mechanism does not catch it the way it catches dissolved salts.
Worse, chloramines can actually damage the RO membrane itself. Research on polyamide thin-film composite membranes, the type used in most residential and commercial RO systems, found that exposure to monochloramine solutions caused a 30% increase in water flux within just the first 6 hours, indicating physical damage to the membrane structure.7Journal of Membrane Science. Investigation of oxidative degradation of polyamide reverse osmosis membranes by monochloramine solutions A damaged membrane lets more contaminants through, defeating the purpose of having RO in the first place.
This is why most quality RO systems designed for chloraminated water include a carbon pre-filter stage. The carbon removes the chloramines before the water ever reaches the membrane, protecting the membrane and ensuring the chloramines are actually eliminated. If you already own an RO system but your water utility uses chloramines, check whether your system includes a carbon pre-filter rated for chloramine removal, not just taste-and-odor carbon, which may be insufficient.
Emerging Membrane Technology
A newer line of research has explored graphene oxide membranes for chloramine removal. In laboratory testing, these membranes reduced both chlorine and monochloramine levels below the detection limit of 0.1 ppm. Thicker graphene oxide membranes maintained this performance for over six days of continuous filtration, while thinner versions developed microcracks and lost effectiveness after about 30 hours.8Journal of Membrane Science. Removal of chlorine and monochloramine from tap water using graphene oxide membranes This technology is still in the research phase and not yet commercially available for home use, but it represents a potentially simpler approach than the carbon-plus-RO combination many households currently rely on.
Special Situations That Demand Serious Removal
For most people, chloramines in drinking water at the levels maintained by water utilities are not a health emergency. The concern becomes acute in specific situations where even trace amounts can cause harm.
Kidney Dialysis
Dialysis patients face the most serious risk. During hemodialysis, large volumes of water come into direct contact with the bloodstream through the dialysis membrane. Chloramines in that water can oxidize hemoglobin and destroy red blood cells. A well-documented incident at an outpatient dialysis center in 1987 illustrates the stakes: when a carbon filter in the water treatment system failed, patients were exposed to chloramine-contaminated dialysate, and 41 patients required blood transfusions to treat the resulting hemolytic anemia.9PubMed. Illness in hemodialysis patients after exposure to chloramine contaminated dialysate Dialysis centers are required to treat water to a very strict standard, keeping monochloramine below 0.1 mg/L, and typically use dual carbon beds with continuous monitoring to ensure no breakthrough occurs.
Aquariums and Fish Keeping
Fish are highly sensitive to chloramines because the compound passes through their gills and directly damages blood cells, similar to the mechanism in dialysis patients. Unlike free chlorine, which dissipates from an open aquarium within a day or so, chloramines persist. Aquarium keepers in chloraminated water districts need to treat every water change. Sodium thiosulfate-based dechlorinators sold at pet stores are formulated for this purpose, and most also bind the ammonia released when the chloramine bond is broken, which would otherwise spike ammonia levels and stress or kill fish.
Homebrewing
Brewers care about chloramines for a different reason: even tiny residual amounts can react with organic compounds in the mash or wort to produce chlorophenols, which create a harsh, medicinal off-flavor detectable at parts-per-billion levels. Carbon filtration or a campden tablet (potassium metabisulfite) crushed into the brewing water are the standard fixes. One campden tablet in 20 gallons of water is a common rule of thumb among homebrewers, and the reaction is nearly instantaneous.
Health Concerns From Chloramine Exposure
For the general population drinking chloraminated tap water, the health evidence does not suggest cause for alarm at regulated concentrations. The more documented health effects relate to airborne exposure, particularly in indoor swimming pools. When chloramines react with organic matter from swimmers (sweat, skin cells, urine), they form volatile byproducts, especially trichloramine, that accumulate in the air above the pool. Multiple studies have shown a relationship between airborne trichloramine levels and eye irritation and upper airway irritation in pool workers and regular swimmers, and exposure can aggravate asthma symptoms in people who already have asthma.10PubMed. Inorganic chloramines: a critical review of the toxicological and epidemiological evidence as a basis for occupational exposure limit setting
If you notice a strong “chlorine smell” in your shower or bathroom, that is often chloramine or its breakdown products volatilizing in the warm, enclosed space. A carbon shower filter or a whole-house carbon system addresses this. Some people with sensitive skin or respiratory conditions report improvement after switching to filtered water in chloraminated districts, though controlled studies on household exposure at typical tap water levels are limited.
What Chloramines Do to Your Plumbing
Chloramines do not just affect you when you drink or bathe. They can quietly degrade certain components inside your home’s plumbing system. After several water utilities switched from free chlorine to chloramines, reports began emerging of accelerated degradation of rubber seals, gaskets, and O-rings in the distribution system and in home plumbing.11Journal AWWA. Drinking water quality concerns from chloramine‐induced degradation of elastomeric compounds Testing confirmed that different rubber compounds react differently: natural rubber, neoprene, nitrile, styrene butadiene rubber, and EPDM all degraded at different rates and in different ways when exposed to chloraminated water.12Opflow. Understand Chloramine’s Effect on Elastomer Components
Interestingly, the real-world picture is not always as bad as laboratory testing suggests. Accelerated lab tests on flat sheets of rubber showed dramatic swelling and degradation, but actual pipe gaskets used in ductile-iron water mains showed only slight chlorine penetration and no visual degradation over a full year of testing.13Journal AWWA. effect of Chloramines on Ductile‐iron Pipe Gaskets of various eslastomer compounds The shape, compression, and design of an installed gasket appear to provide some protection that flat test coupons do not have. Still, if you live in a chloraminated water district and notice toilet flappers or washing machine hoses failing prematurely, chloramine exposure is a plausible contributor. Replacing rubber components with chloramine-resistant materials (certain EPDM formulations or silicone) can extend their life.
A separate plumbing concern involves the bacteria that naturally colonize the inside of your home’s pipes. Chloramines are more stable than free chlorine, which is an advantage in long distribution mains, but inside the shorter, warmer pipes of a home, certain bacteria called nitrifiers can colonize the pipe walls and actually break down the chloramine, consuming it as a nitrogen source. Research has shown that when nitrification takes hold in household plumbing, chloramine decay rates accelerate dramatically, and the resulting loss of disinfectant residual can lead to higher levels of bacteria in the water than would be found with free chlorine.14Journal AWWA. Accelerated chloramine decay and microbial growth by nitrification in premise plumbing This is one of the counterintuitive downsides of chloramination that does not get much public attention.
The Lead Leaching Problem
Perhaps the most consequential infrastructure issue with chloraminated water involves lead. The most prominent case study is Washington, D.C., where a switch from free chlorine to chloramine as the secondary disinfectant triggered a crisis of elevated lead levels in drinking water. Research found that free chlorine reacts with dissolved lead to form an insoluble lead solid that essentially coats and seals lead service lines and solder joints, keeping lead out of the water. Chloramine does not produce this protective reaction.15Journal AWWA. role of chlorine and chloramine in corrosion of lead‐bearing plumbing materials
Further testing showed that chloramines sometimes dramatically worsened lead leaching from brass fixtures compared to free chlorine. In Washington, the highest lead concentrations were found not in the first draw of water from the tap, but after about a minute of flushing, which was particularly troubling because utilities had been telling residents to flush for a minute to reduce lead exposure.15Journal AWWA. role of chlorine and chloramine in corrosion of lead‐bearing plumbing materials If you live in an older home with lead service lines or lead solder joints and your utility uses chloramines, a point-of-use filter certified for lead removal (NSF/ANSI Standard 53) is worth considering regardless of your interest in chloramine removal itself.
Disinfection Byproducts and Chloraminated Water
One reason utilities switched to chloramines in the first place was to reduce the formation of certain disinfection byproducts, particularly trihalomethanes and haloacetic acids, which form when free chlorine reacts with organic matter in water. Chloramination does reduce those particular byproducts. But chloraminated water produces its own set of byproducts, including N-nitrosodimethylamine (NDMA), a probable human carcinogen that has been detected in chloraminated drinking water systems.16PubMed. The role of chloramine species in NDMA formation
NDMA formation depends on the specific organic precursors present in the source water. Water sources that contain certain nitrogen-containing organic compounds, including those from algal blooms, are more prone to producing NDMA during chloramination.17PubMed. Comparison of the formation of N-nitrosodimethylamine (NDMA) from algae organic matter by chlor(am)ination and UV irradiation NDMA is not currently regulated under federal drinking water standards in the United States, though it is monitored and several states have set advisory levels. Activated carbon filtration can reduce NDMA concentrations along with removing the chloramines themselves, which is one more reason a quality carbon filter serves double duty in a chloraminated water district.
How to Test What Is in Your Water
Before investing in treatment equipment, it helps to confirm that your water actually contains chloramines and at what level. Your water utility’s annual Consumer Confidence Report (or Water Quality Report), which is required by the EPA and usually available on the utility’s website, will tell you what disinfectant is used and the average residual levels at the tap. Typical monochloramine residuals in distribution systems range from about 1 to 4 mg/L.
For real-time testing at your own tap, inexpensive test strips and colorimetric test kits are available from pool supply and aquarium stores. The important thing is to use a kit that differentiates between free chlorine and total chlorine. The difference between those two readings gives you a rough estimate of the combined chlorine (chloramine) level. DPD-based test kits are widely available and work for this purpose. If you are treating water for a sensitive application like dialysis or a reef aquarium, a more precise digital colorimeter is worth the investment so you can confirm your removal system is performing.