Why Does My Tap Water Smell Like a Swimming Pool?

A swimming-pool-like smell in tap water often comes from a chlorine-based disinfectant or from compounds formed during disinfection, but smell alone cannot tell you which one is responsible. A fast way to start narrowing it down: does the smell happen in both hot and cold water, at every fixture in your home?

If it is the disinfectant, and your water meets drinking-water standards, EPA considers it safe for drinking, cooking, and bathing. Which disinfectant you actually have decides which fix works, so the sections below walk through how to identify it before recommending anything.

Free Chlorine vs. Chloramine

What Causes the Swimming-Pool Smell in Tap Water?

The swimming-pool smell in tap water traces back to one of two distinct chemical pathways, and they are not the same thing. When chlorine reacts with ammonia, it forms chloramines, a deliberate secondary disinfectant many utilities add on purpose.

When chlorine reacts with natural organic matter instead, it forms a different category entirely: disinfection byproducts, including trihalomethanes (THMs) and haloacetic acids (HAAs). Chlorine plus organic matter does not make chloramine. It makes disinfection byproducts, and confusing the two is the single most common mistake in explaining this smell.

Chloramine itself is a family of related compounds, not one single chemical. Monochloramine is the form utilities intentionally create and maintain, and they hold a target pH specifically so that monochloramine, rather than other chloramine species, is what forms. Dichloramine and other chloramine species form at much lower levels under normal drinking-water treatment conditions.

Characteristics of Chloramine

The characteristic odor of indoor swimming pools is strongly associated with chloramines, particularly more highly chlorinated species such as trichloramine.

According to the CDC's Healthy Swimming program, if you smell "chlorine" at a pool, you are probably smelling chloramines that have moved from the water into the surrounding air, a phenomenon more common at indoor pools with limited ventilation. 

Importantly, the CDC is explicit that the chloramines that form in pool water are different from the chloramine sometimes used to treat drinking water.

Pool-associated chloramines and the monochloramine used in your tap water belong to the same chemical family, but they are not the same compound, formed under the same conditions, or present at the same concentrations.

Utilities that use chloramine generally do so for two related reasons. According to EPA, chloramine is a weaker disinfectant than free chlorine but is more chemically stable, meaning it persists longer as water travels through a distribution system. More than one in five Americans use drinking water treated with chloramines, per EPA's estimate. 

Why Does My Tap Water Suddenly Smell Stronger?

A sudden, temporary change in smell often traces back to something your utility is doing on a schedule, not a new problem with your water. Some utilities that use chloramine periodically switch to free chlorine for a few weeks, sometimes called a chlorine burn, to scour biofilm from distribution pipes.

DC Water and the Washington Aqueduct, for example, run an annual temporary switch from chloramine to chlorine, typically in spring, noting customers may notice a temporary taste and smell change.

The City of Sugar Land, Texas, describes the same practice, pairing a temporary conversion with flushing to clear organic buildup from the pipes. This isn't universal practice at every utility, and schedules, where they exist, are often posted in advance.

What are the Factors of Strong Smells

Water main flushing is a related but separate maintenance activity, where a utility opens hydrants in sequence to pull fresh water through the system, which can temporarily stir up sediment and disinfectant residual in a way that's more noticeable than normal.

Warm weather plays a role too, in a way that's easy to test yourself: a hot tap carries odor more noticeably than a cold glass drawn from the same supply line, simply because warmer water releases more of any dissolved gas or volatile compound into the air you're smelling.

Standing water is another factor. Water that has been sitting in household plumbing, for example overnight or while you were away, can have a noticeably different taste or odor from freshly drawn water, simply from interacting with the plumbing itself rather than any concentration effect.

Your position in the distribution system also matters: homes near the start of a distribution loop tend to have a stronger, fresher disinfectant residual than homes near the end of a long pipe run, where residual levels naturally decline over distance and time.

Finally, personal detection thresholds vary substantially from person to person. It's entirely normal for one person in a household to notice an odor that another doesn't, and this difference doesn't by itself indicate anything is wrong with the water.

What Else Can Make Tap Water Smell Strange?

Not every unusual smell traces back to a disinfectant at all. A few other common causes are worth ruling out before assuming your water utility is the source.

Other Common Causes

The hot-versus-cold comparison deserves its own thirty seconds of attention, because it's one of the fastest ways to separate an incoming-supply problem from a water-heater problem. Fill two glasses, one from the hot tap and one from the cold tap at the same faucet, and smell them side by side.

If only the hot water smells off, the water heater itself, not your incoming supply, is the more likely source, since certain water heater conditions can produce their own distinct odors unrelated to what's coming from the utility.

The single-fixture case deserves a specific check too. If only one faucet or fixture smells off while everything else in the house is normal, the smell may actually be coming from the drain itself rather than the water.

Pour a sample into a clean glass and smell it away from the sink; if the water itself smells fine once separated from the drain opening, the fixture's drain, trap, or garbage disposal is the more likely source, not your water supply.

Decision path:

• Every tap, hot and cold → investigate the incoming water and its disinfectant.

• Hot water only → investigate the water heater or household plumbing.

• One fixture only → investigate that fixture or its drain.

• Started suddenly across the whole house → check utility notices, flushing schedules, or a disinfectant change.

• Utility confirms chloramine → look for a filter specifically tested for chloramine reduction.

• Utility confirms free chlorine → conventional activated carbon may be sufficient.

How Can I Tell Whether My Water Has Chlorine or Chloramine?

Your Consumer Confidence Report is the most authoritative place to start, since utilities are required to publish one annually by July 1 naming the disinfectant they use and reporting measured levels.

Asking your utility directly is often the fastest option, and they can also tell you whether a temporary disinfectant switch, like the seasonal chlorine burns described above, happens to be running right now.

Chlorine test strips can offer a rough signal if you're willing to do a bit of arithmetic: free chlorine plus combined chlorine equals total chlorine, so subtracting your free chlorine reading from your total chlorine reading gives you the combined chlorine figure.

However, combined chlorine can indicate chloramine or other combined chlorine species, so a combined chlorine reading on a test strip is not a definitive chloramine identification on its own. Your utility remains the best source for identifying its disinfectant with certainty.

Smell can offer a hint, with a real caveat attached: a sharp, bleach-like smell leans toward free chlorine, while a milder, faintly ammonia-like smell leans toward chloramine. Treat this as a hint, not a substitute for checking your CCR or asking your utility directly.

One more thing worth closing the loop on: if your utility confirms a different disinfectant than you assumed, or tells you the odor you're noticing isn't actually related to their disinfectant residual at all, don't choose a filter based on smell alone.

The wrong assumption here leads directly to buying a filter that isn't matched to what's actually in your water.

What Removes Chlorine and Chloramine From Tap Water?

Several common home remedies work well on free chlorine and poorly, or not at all, on chloramine, which is exactly the gap that causes the most confusion when people try to fix this on their own.

What Actually Works, by Method

Letting water sit lets free chlorine off-gas into the air over time, which is why open-pitcher water can lose its chlorine smell after sitting out. This does little for chloramine, since chloramine is far more chemically stable and doesn't off-gas the same way. Boiling removes free chlorine but does not remove chloramine; boiling doesn't make chloramine worse, it simply isn't an effective removal method for it.

Standard activated carbon, whether granular activated carbon (GAC), carbon block, or the carbon inside pitchers, faucet-mount filters, refrigerator filters, or whole-house tanks, is genuinely excellent at removing free chlorine. It performs far less well against chloramine, reaching what's called breakthrough (the point where the media stops effectively reducing the target compound) much faster than it does with free chlorine.

Catalytic carbon is one of the principal carbon-media approaches specifically developed for chloramine reduction, though it isn't the only consideration and isn't automatically superior for every situation. It's manufactured with modified surface chemistry that promotes catalytic decomposition of chloramine, rather than relying purely on adsorption the way standard carbon does.

In one column study reported in WaterWorld, at a 3 ppm chloramine concentration, standard granular activated carbon reached breakthrough at about 10 minutes, while catalytic carbon lasted roughly 50 minutes under the same conditions.

The same study found standard coconut-shell carbon decomposed about 20% of a hydrogen peroxide test solution within 10 minutes of contact time, versus more than 95% for catalytic carbon under identical conditions, a common way of measuring catalytic activity. 

These are study results under specific test conditions, not a guaranteed multiplier for every product on the market. Catalytic carbon is commonly sold in granular form, though product design varies, and a carbon block doesn't automatically perform the same way a granular bed does. 

Certification is worth checking directly rather than assuming. NSF/ANSI 42 covers aesthetic effects, and chlorine reduction is the most common claim tested under it.

Chloramine reduction is a separate, specific claim a product must be independently tested and certified for; a filter certified to 42 for chlorine is not automatically verified for chloramine. Certification attaches to a specific model, not a brand as a whole.

Check a specific model against NSF's certified products listing or the WQA Gold Seal database before buying based on a certification claim.

One more practical note: an overdue filter cartridge makes taste and odor worse, not better, regardless of which disinfectant it was sized to handle.

Which Water Filter Is Right for Chlorine or Chloramine?

The right filter depends on which disinfectant you actually have, where in your home you want it treated, and whether the specific product is verified for that job.

Filter Selection by Situation

The relationship that matters isn't simply "chloramine, so buy catalytic carbon." It runs from disinfectant, to treatment media, to treatment location, to contact time and flow requirement, to a verified reduction claim, and only then to a specific product.

Two catalytic carbon filters can perform very differently depending on flow rate rating and whether the specific model carries a verified chloramine certification. Confirming each link in that chain is what determines whether a filter performs the way you expect.

Browse chloramine reduction filters and systems →

Identify the disinfectant, match the media, verify the certification claim, size for your actual flow rate, and set a replacement schedule. That sequence, in that order, is what makes the difference between a filter that solves the problem and one that simply looks like it should.

Frequently Asked Questions

Can chloramine make tap water smell like chlorine?

Yes. Chloramine has a milder, more ammonia-like smell than free chlorine's sharper bleach-like odor, but many people still describe both as a general "chlorine smell." The specific character of the smell can offer a hint about which disinfectant is present, though your Consumer Confidence Report is the more reliable way to confirm it.

Why does my cold water smell fine but my hot water smells bad?

This points to your water heater or household hot-water plumbing rather than your incoming water supply. Compare a glass of cold water and a glass of hot water from the same faucet; if only the hot water smells off, the water heater is the more likely source, since it can develop its own distinct odor independent of the water utility.

Does letting chloraminated water sit overnight remove the smell?

Not reliably. Letting water sit uncovered allows free chlorine to off-gas into the air, which can reduce a chlorine smell over time. Chloramine is far more chemically stable and largely does not off-gas the same way, so sitting out overnight does little to reduce a chloramine-related odor.

Does boiling water remove chlorine and chloramine?

Boiling removes free chlorine but does not remove chloramine. Boiling doesn't make chloramine worse; it simply isn't an effective method for removing it, unlike its effect on free chlorine.

Does NSF/ANSI 42 mean a filter removes chloramine?

Not automatically. NSF/ANSI 42 covers aesthetic effects, and chlorine reduction is the most commonly tested claim under it. Chloramine reduction is a separate, specific claim that a product must be independently tested for, so a filter certified to NSF/ANSI 42 for chlorine is not automatically certified for chloramine as well.

Does a shower filter remove chloramine?

Some shower filters are designed and tested for chloramine reduction, but not all of them are, since standard carbon media performs poorly against chloramine compared to free chlorine. Check the specific product's certification and tested claims for chloramine, rather than assuming any shower filter handles it.

Why does my tap water smell like chlorine after the utility flushes the water main?

Water main flushing can temporarily stir up sediment and disinfectant residual in a way that's more noticeable than normal, and some utilities also run a temporary switch to a different disinfectant around the same time as scheduled maintenance. This is typically a short-term condition tied to the maintenance activity itself, not a new ongoing problem with your water.

Can chlorinated or chloraminated tap water hurt fish?

Yes. Chlorine, and especially chloramine, are harmful to aquatic life, since fish absorb them readily through their gills. Use a water conditioner rated specifically for your utility's actual disinfectant, since a plain dechlorinator can neutralize chlorine while leaving free ammonia behind, which is itself toxic to fish.