Nearly every US public water system disinfects its water before delivery. The two technologies used to do that are chlorine (used by about 70% of US utilities) and chloramine (a chlorine-ammonia compound used by the rest, including many large urban systems like Los Angeles, San Francisco, and Washington DC). Both kill bacteria, viruses, and pathogens at the treatment plant and as the water travels through the distribution system. Without disinfection, waterborne disease would kill thousands of Americans each year, as it did before chlorination became widespread in the early 20th century.
Both also cause side effects worth understanding — and both can be filtered out at the home tap.
Updated October 2026: product certification details corrected.
Chlorine vs. chloramine — what’s the difference
Free chlorine is elemental chlorine dissolved in water (technically hypochlorous acid). It’s a powerful, fast-acting disinfectant. It dissipates quickly — leave a glass of tap water out for a few hours and most of the chlorine taste goes away. That makes it the simpler disinfectant to remove, but it also means utilities need to add more of it to maintain residual disinfection throughout the distribution system.
Chloramine is chlorine combined with ammonia. It’s a weaker disinfectant per unit, but it’s much more stable — it persists through long distribution pipes and tanks. That’s why large metropolitan systems with sprawling pipe networks favor it. Chloramine does not dissipate when you let water sit out, and it’s significantly harder to filter.
Are chlorine and chloramine themselves harmful?
At the concentrations US utilities use (typically 1-4 mg/L for either), neither chlorine nor chloramine is considered acutely toxic to humans. The EPA’s legal limit (called the MRDL, or Maximum Residual Disinfectant Level) is 4 mg/L for both. EWG’s health guideline is more conservative but still treats typical levels as low-direct-risk.
The bigger issue isn’t the disinfectants themselves — it’s the disinfection byproducts (DBPs) they form when chlorine or chloramine reacts with organic matter in the source water. Total trihalomethanes (TTHMs) and haloacetic acids (HAA5) are the regulated examples. These are associated with bladder cancer and adverse pregnancy outcomes at long-term elevated exposure. See our disinfection byproducts guide for more.
Three other notes worth flagging:
Taste and smell. Most people can taste chlorine above 1 ppm and find it unpleasant. Chloramine has a milder odor but tastes slightly metallic to some.
Aquariums and fish. Chlorine evaporates in 24 hours but chloramine does not. Tap water with chloramine will kill fish unless dechlorinated. A simple activated carbon filter or a dose of dechlorinator before adding water to a tank handles this.
Sensitive individuals. A small subset of people report skin irritation, dryness, or breathing issues (during hot showers when chloramine off-gases) from chloraminated water. The medical evidence is weaker than the anecdotes, but the experience is real for those affected.
How to know which one your utility uses
Every utility’s annual Consumer Confidence Report (CCR) states the disinfection method. We list it on every utility’s TapWaterSafety page under the “About this water system” section. As a rough rule:
- Free chlorine: smaller systems, surface water with relatively pristine source water, systems with short distribution networks
- Chloramine: large urban systems, systems with extensive pipe networks, systems that have switched to reduce DBP formation (chloramine generates less TTHM/HAA5)
If you’re not sure, the simple test: fill a glass with tap water, let it sit overnight uncovered, and taste it. If the chlorine taste is gone in the morning, you have free chlorine. If it’s still there, you have chloramine.
How to filter chlorine and chloramine
Both are removed by activated carbon, but with different efficacy and contact time requirements.
For chlorine
Almost any quality activated carbon filter handles free chlorine effectively. NSF/ANSI Standard 42 certification specifically tests for chlorine reduction. The bar to clear is low — a basic carbon pitcher filter (Brita, ZeroWater) will get you most of the way there.
For chloramine
Chloramine is much harder to remove. It binds to ammonia and requires longer contact time with activated carbon (specifically catalytic carbon, a denser form). Standard pitcher filters often don’t remove chloramine effectively.
Look for filters specifically rated for chloramine reduction. The certifications to look for: NSF/ANSI 42 with “chloramine reduction” claim explicitly, not just “chlorine reduction.” Reverse osmosis systems also reliably handle chloramine.
Top filter recommendations for chlorine and chloramine
Best pitcher for chlorine: Clearly Filtered Water Pitcher (certified to NSF/ANSI 42 and 372 for chlorine, taste, and odor; around $80-95) or the Waterdrop Chubby pitcher (certified to NSF/ANSI 42). Neither pitcher’s certification listing includes chloramine, so if your utility uses chloramine, choose one of the options below.
Best under-sink option (chlorine and chloramine): Aquasana AQ-5300. Three-stage activated carbon system, certified by WQA to NSF/ANSI 42, 53, 401, and 372, including chlorine and chloramine reduction. Around $180-240, with 6-month filter life.
Maximum protection: Reverse osmosis (AquaTru or Aquasana OptimH2O). These systems include carbon stages; AquaTru is certified for both chlorine and chloramine reduction, and both handle a wide range of other certified contaminants. Overkill if chlorine taste is your only issue, perfect if you also want to address heavy metals, DBPs, or PFAS.
What does NOT work
- Letting water sit out — works for free chlorine, does not work for chloramine
- Boiling water — accelerates chlorine evaporation but does not remove chloramine
- Most refrigerator filters — check the spec sheet; many are only rated for chlorine, not chloramine
- “Alkaline” or hydrogen water pitchers without specific carbon stage rated for chloramine
The bottom line
Chlorine and chloramine are necessary public health interventions — without them, US tap water would not be safe to drink at scale. They’re also easy to filter out at the kitchen tap, which gives you both the safety benefit of utility disinfection and the taste/sensitivity benefit of removing the disinfectant before drinking.
If your utility uses chlorine, a basic carbon pitcher works fine. If it uses chloramine, you need a filter specifically rated for chloramine removal — confirm a chloramine reduction claim in the certifier’s listing before purchasing.
Looking up your specific water utility? Find your water by ZIP code to see your disinfection method, your contaminant levels, and recommended filters matched to your specific water profile.