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Chlorine and chloramine are disinfectants added to kill bacteria. While necessary for safe water, they create harmful byproducts, cause taste and odor issues, and may irritate skin and respiratory systems.
Chlorine has been used to disinfect drinking water since the early 1900s, and its introduction is considered one of the greatest public health achievements of the 20th century. Before chlorination, waterborne diseases like cholera and typhoid killed thousands of Americans each year. Today, virtually all public water systems in the United States use some form of chlorine-based disinfection to ensure water is safe to drink.
Chlorine works by destroying the cell walls of bacteria, viruses, and parasites, rendering them harmless. When added to water at treatment plants, it provides residual disinfection that continues to protect water as it travels through distribution pipes to your tap. This residual is essential because water can pick up contamination from pipe breaks, biofilm growth, or other issues in the distribution system.
Chloramine is a compound formed by combining chlorine with ammonia. About 68 million Americans (roughly 1 in 5) receive chloraminated water. Water utilities switched to chloramine because it produces fewer disinfection byproducts than chlorine alone, lasts longer in distribution systems, and provides more consistent disinfection throughout the pipe network.
While chlorine and chloramine themselves are considered safe at regulated levels, the disinfection byproducts they create pose the primary health concern. Additionally, some individuals are more sensitive to these chemicals than others.
Research suggests pregnant women exposed to high levels of disinfection byproducts may face increased risks. Some studies have found associations between high THM exposure and miscarriage, low birth weight, and neural tube defects, though findings are not conclusive.
Children consume more water relative to their body weight than adults, potentially increasing their exposure. While routine chlorine levels are safe for children, minimizing exposure to disinfection byproducts is advisable.
For most healthy adults, chlorine and chloramine at regulated levels pose minimal immediate health risks. The primary concerns are long-term exposure to disinfection byproducts and quality-of-life issues like taste and odor.
While chlorination protects these vulnerable groups from waterborne pathogens, they may also be more susceptible to irritation from chlorine and its byproducts.
Certain groups must remove chlorine and chloramine from water due to specific sensitivities:
When chlorine reacts with naturally occurring organic matter in water (from decaying leaves, algae, and other sources), it creates disinfection byproducts (DBPs). These compounds pose greater health concerns than chlorine itself and are the main reason some health advocates are concerned about chlorinated water.
The most common DBPs, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. THMs are classified as possible human carcinogens and have been linked to bladder cancer in epidemiological studies.
EPA limit: 80 micrograms per liter (annual average)
Another group of DBPs formed during chlorination. The EPA regulates five HAAs (HAA5), including dichloroacetic acid and trichloroacetic acid. Associated with liver toxicity and cancer in animal studies.
EPA limit: 60 micrograms per liter (annual average)
Byproducts of chlorine dioxide disinfection. Can affect red blood cells and nervous system at high levels.
MRDL = Maximum Residual Disinfectant Level
These standards represent a balance between ensuring water is adequately disinfected to prevent waterborne disease while limiting exposure to disinfection byproducts. Water utilities must maintain minimum residual disinfection levels while staying below maximum limits.
The EPA acknowledges that disinfection byproducts pose health risks but emphasizes that the benefits of disinfection in preventing waterborne disease outweigh these risks. Untreated water can contain dangerous pathogens that cause immediate, severe illness, while DBP-related health effects occur over decades of exposure.
Unlike most contaminants that enter water accidentally, chlorine and chloramine are intentionally added at water treatment plants. Understanding this process helps explain why levels vary and what you can expect in your tap water.
At the treatment plant, chlorine is typically added after filtration to kill remaining pathogens. The water is held in contact tanks long enough for disinfection to occur before entering the distribution system.
A small amount of disinfectant remains in the water as it travels through pipes. This residual protects water from recontamination during distribution. Chloramine is often preferred for this role because it lasts longer in pipes.
In large distribution systems, additional chlorine may be added at booster stations throughout the network to maintain adequate residual levels at the far reaches of the system.
Utilities periodically flush water mains to remove sediment and biofilm. After flushing, chlorine levels may temporarily increase. You might notice stronger chlorine taste or odor during these events.
Chlorine levels at your tap depend on distance from the treatment plant, water age in pipes, pipe material and condition, temperature (warmer water uses up chlorine faster), and time of year. Homes closer to treatment plants or booster stations typically have higher chlorine levels.
Testing for chlorine is simple and inexpensive, while testing for disinfection byproducts requires laboratory analysis.
Most people do not need to test regularly since utility data is available. Consider testing if you notice strong chlorine taste or odor, have sensitive skin that seems irritated by tap water, want to verify filter performance, or are curious about levels at your specific location in the distribution system.
The most common and effective method for home use. Carbon adsorbs chlorine as water passes through. Available in pitcher filters, faucet-mount, under-sink, and whole-house systems. Most affordable option with excellent results.
Cost: $20-50 for pitchers; $100-300 for under-sink; $500-2,000 for whole-house
Chlorine naturally evaporates when water is exposed to air. Fill a pitcher and let it sit uncovered for 30-60 minutes. Free and easy, but only works for chlorine (NOT chloramine). Not practical for large volumes.
Vitamin C neutralizes chlorine instantly through a chemical reaction. Used in some shower filters and for dechlorinating bath water. One gram neutralizes approximately 1 mg of chlorine per liter.
RO systems remove chlorine along with many other contaminants. Point-of-use systems typically include carbon pre-filters that remove chlorine before it can damage the RO membrane.
Specially treated activated carbon designed for chloramine removal. More effective than standard carbon. Look for filters specifically rated for chloramine or look for catalytic carbon designation.
Multi-stage RO systems effectively remove chloramine. The carbon pre-filter handles chloramine while the RO membrane removes other contaminants. Best overall protection.
For removing chloramine from all water in your home, including showers and baths. Larger investment but provides comprehensive protection.
Important: Standard carbon filters and letting water sit do NOT effectively remove chloramine. Always verify your filter is rated for chloramine if that is what your utility uses.
For drinking water only, point-of-use filters (under-sink or countertop) are cost-effective. If you experience skin or respiratory irritation from showers, consider whole-house filtration or a dedicated shower filter. Whole-house systems cost more but treat all water entering your home.
Yes, boiling accelerates chlorine evaporation. Boiling for 15-20 minutes removes most chlorine. However, boiling does NOT effectively remove chloramine and is impractical for large water volumes. Filtration is more convenient.
Chlorine levels fluctuate based on several factors: distance from treatment plant, time of year (utilities increase levels in summer), system maintenance activities, and water temperature. Levels are typically higher after system flushing or repairs.
For most people, yes. However, the warm shower environment causes chlorine to vaporize and be inhaled. This exposure may irritate lungs in sensitive individuals. Hot showers also open pores, potentially increasing skin absorption. Shower filters can help if you experience irritation.
Boiling water for cooking removes most chlorine anyway. However, using filtered water ensures consistent taste and eliminates any chlorine before cooking. If you are concerned about DBPs, filtered water is recommended since some byproducts can vaporize during cooking.
Check your water utility's Consumer Confidence Report or call them directly. You can also test: leave water uncovered overnight - if the chlorine smell disappears, it is chlorine. If the smell persists, it is likely chloramine.