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Chlorine vs. Chloramine for Water Disinfection

What is chloramine?

Chloramines (NH2Cl) are formed when there is a reaction between free chlorine (Cl2) and ammonia (NH3). The ideal pH for the reaction is 8.4, making the water slightly alkaline. Chloramines may be used as bleach, disinfectants or oxidators.

Using Chloramines for the Disinfection of Water

To disinfect water using chloramines, ammonia is added to previously chlorine-treated water. Municipal water treatment systems are beginning to make the switch from using chlorines to using chloramines instead, for the disinfection of water. Here are the pros and cons of using chloramine instead of chlorine:


  1. Using chlorine as a disinfectant results in the production of trihalomethanes (THM) and other carcinogenic byproducts. Few are formed when chloramines are used.
  2. Chloramines remain active in water for longer than chlorine, ensuring safety from waterborne pathogens for a longer period of time. Chlorine dissipates once it has been boiled, or exposed to air for an extended period.
  3. Many people choose to filter water that has been disinfected with chlorine, because of the bad taste and odor that chlorine leaves behind. However, chloramines improve the taste and smell of water.


  1. Using chloramine as a disinfectant often results in the formation of organic chloramines. These form when there is a large amount of organic material (>3ppm) present in the water. Organic chloramines are less effective at disinfection than inorganic chloramines.
  2. Chloramine is less reactive than chlorine, requiring a longer reaction time for effective disinfection. Part of the disinfectant remains in the water to be consumed by bacteria or broken down, a process which can take weeks. 
  3. While chlorine perishes when water lies still for a few days, chloramines do not and must be removed from the water instead, using granular activated carbon or acetic acid.
  4. Chloramines may be less effective than chlorine for the removal of pathogens, even though the EPA claims that they are as effective. Any studies refuting the EPA's claims have not been published.
  5. High amounts of ammonia in water can cause nitrate levels to rise. Nitrates cause the oxygen level in the blood to fall and can be carcinogenic. 
  6. When chloramines are removed, ammonia may be released. Ammonia causes corrosion of lead and copper, of which most water pipes are made. (Orthophosphates may be added to reduce corrosion.)
  7. Adding chloramine to the water supply can increase exposure to lead, due to the corrosion of lead pipes, resulting in increased lead levels in the bloodstream, which can pose a significant health risk.
  8. Exposure to chloramines may also cause respiratory problems, including asthma, especially in swimmers - if it is used in swimming pools. Chloramines may also have an effect on the lungs, if inhaled during a hot shower. 
  9. Like chlorine, chloramines are toxic to fish and cannot be used in aquarium water.

Removing Chloramines From Drinking Water

It appears that the disadvantages of disinfecting water with chloramine outweigh the advantages. Even though they improve the taste and odor of water, many people still choose to remove it, because of the potential carcinogenic effects. Chloramines can be removed by special type of granular active carbon filter, designed specifically for chloramine removal. Chloramines are difficult to remove by reverse osmosis filtration. Contact time is significant for the removal of chloramines from water. The longer the water is in contact with the filter, the more contaminants are removed. Filters Fast carries several types of chlorine and chloramine water filters.


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