Chloramine vs. Chlorine

What's the Difference?

Chloramine and chlorine are both disinfectants commonly used in water treatment processes. However, they differ in their chemical composition and properties. Chlorine is a strong oxidizing agent that rapidly kills bacteria and viruses in water. It is highly effective in eliminating pathogens but can produce by-products, such as trihalomethanes, which are potentially harmful to human health. On the other hand, chloramine is a combination of chlorine and ammonia. It is less reactive than chlorine and provides a longer-lasting residual disinfectant in the water distribution system. Chloramine is known to produce fewer disinfection by-products, making it a preferred choice in some water treatment facilities. However, it is less effective against certain pathogens and requires longer contact time for disinfection.


Chemical FormulaNH2ClCl2
CompositionCombination of ammonia and chlorineElemental chlorine
OdorLess noticeable odor compared to chlorineStrong, distinct odor
Disinfection EfficiencySlower acting, but longer-lasting disinfectantFast-acting disinfectant
StabilityRelatively stable, remains in water for longer periodsLess stable, tends to dissipate more quickly
ByproductsForms fewer disinfection byproductsForms more disinfection byproducts, such as trihalomethanes
Effect on pHIncreases pH slightlyDoes not significantly affect pH
UsageCommonly used in water treatment as an alternative to chlorineCommonly used in water treatment for disinfection

Further Detail


When it comes to water treatment, two common disinfectants used are chloramine and chlorine. Both substances are effective in killing harmful bacteria and viruses, but they have distinct attributes that make them suitable for different applications. In this article, we will explore the characteristics of chloramine and chlorine, their advantages, disadvantages, and their impact on human health and the environment.


Chloramine, also known as monochloramine, is a compound formed by the reaction of chlorine with ammonia. It is commonly used as a secondary disinfectant in water treatment plants and is particularly effective in controlling the growth of biofilms and reducing the formation of disinfection byproducts (DBPs). Chloramine has a longer-lasting residual effect compared to chlorine, which means it can provide continuous disinfection throughout the distribution system.

One of the advantages of chloramine is its stability. Unlike chlorine, chloramine does not readily dissipate when exposed to sunlight or heat, making it a reliable disinfectant for water that needs to travel long distances through pipelines. Additionally, chloramine has a milder odor and taste compared to chlorine, which can be appealing to consumers who are sensitive to the strong smell and taste of chlorine in tap water.

However, chloramine has some drawbacks. It is less effective than chlorine in killing certain pathogens, such as Cryptosporidium, which is a parasite that can cause gastrointestinal illness. Chloramine also requires a longer contact time to achieve the same level of disinfection as chlorine, which can be a challenge in emergency situations where rapid disinfection is necessary.

Another concern with chloramine is its potential to corrode certain types of plumbing materials, such as lead and copper. This can lead to the leaching of these metals into the water, posing a risk to human health. To mitigate this risk, water utilities using chloramine often implement corrosion control measures, such as adjusting the pH and adding corrosion inhibitors.


Chlorine is the most commonly used disinfectant in water treatment worldwide. It is highly effective in killing a wide range of pathogens, including bacteria, viruses, and protozoa. Chlorine is a strong oxidizing agent that rapidly reacts with organic matter, destroying harmful microorganisms in the process. It is also relatively inexpensive and easy to produce, making it a cost-effective choice for large-scale water treatment.

One of the key advantages of chlorine is its rapid disinfection capability. It can quickly neutralize pathogens, making it ideal for emergency situations or when immediate disinfection is required. Chlorine also has a long history of use and is well-studied, with established guidelines and regulations in place to ensure its safe and effective use.

However, chlorine has some drawbacks as well. It can react with organic matter present in water to form disinfection byproducts (DBPs), such as trihalomethanes (THMs) and haloacetic acids (HAAs). Some DBPs are known to be carcinogenic and can pose health risks if consumed in high concentrations over a long period. To address this issue, water treatment plants often employ advanced treatment processes, such as activated carbon filtration, to remove or reduce DBPs.

Another concern with chlorine is its strong odor and taste. Many people find the smell and taste of chlorine in tap water unpleasant, which can lead to a decrease in consumer satisfaction. However, chlorine can be easily removed or reduced through the use of activated carbon filters or by allowing the water to sit exposed to air for a period of time.

Impact on Human Health and the Environment

Both chloramine and chlorine have potential impacts on human health and the environment. Chloramine has been associated with respiratory issues, particularly in individuals with pre-existing respiratory conditions, such as asthma. It can also cause skin and eye irritation in some individuals. However, the health risks associated with chloramine are generally considered to be lower compared to chlorine.

Chlorine, on the other hand, has a stronger disinfection capability but can produce harmful DBPs. Long-term exposure to high levels of DBPs has been linked to an increased risk of bladder and colorectal cancer. However, it is important to note that the levels of DBPs in treated water are regulated and monitored to ensure they are within acceptable limits.

In terms of environmental impact, both chloramine and chlorine can have adverse effects on aquatic ecosystems. Chloramine has been found to be toxic to fish and other aquatic organisms at high concentrations. Chlorine, when discharged into water bodies, can react with organic matter and form toxic compounds that can harm aquatic life. To minimize these impacts, water treatment plants often dechlorinate the water before discharging it into the environment.


In conclusion, chloramine and chlorine are both effective disinfectants used in water treatment, each with its own set of advantages and disadvantages. Chloramine provides a longer-lasting residual disinfection and has a milder taste and odor compared to chlorine. However, it is less effective against certain pathogens and can potentially corrode plumbing materials. Chlorine, on the other hand, offers rapid disinfection and is highly effective against a wide range of pathogens. However, it can form disinfection byproducts and has a strong taste and odor. Both substances have potential health and environmental impacts that need to be carefully managed. Ultimately, the choice between chloramine and chlorine depends on the specific requirements of the water treatment application and the balance between disinfection efficacy, cost, and potential risks.

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