What is Chloramine in Water Treatment?

Dec. 22, 2021

Breaking down what is chloramine in water treatment, & the pros &. cons of chloramine use

About the author:

Brian Campbell founder for WaterFilterGuru.com. Campbell can be reached at [email protected].

All public drinking water must be treated before it can be delivered to our homes. A big part of the water treatment process involves using a chemical disinfectant to kill microorganisms like viruses and bacteria, making water safe to drink. 

Traditionally, chlorine was used to disinfect water. Nowadays, however, a compound combining chlorine and ammonia is rapidly increasing in popularity: chloramine. 

This quick guide will look at how chloramine works to disinfect water, what makes it different to chlorine disinfection, and why chloramine is becoming so popular in the water treatment industry.

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What is Chloramine?

Chloramine is made from a group of chemicals that contain ammonia and chlorine. The most commonly used chloramine in municipal water treatment is monochloramine. This is added to water in measured amounts, ensuring that microorganisms are killed, but water is still safe to drink. 

The EPA estimates that today, more than one in five Americans drink water that has been disinfected with chloramine. 

Water containing up to 4 milligrams per liter (mg/L) or 4 parts per million (ppm) of chloramine is safe for drinking, bathing, cooking, and other household uses, and meets the EPA’s regulatory standards. Health effects are unlikely to occur when chloramine is present in these levels. 

How Does Chloramine Disinfect Water?

As a chlorine-based compound, chloramine is one of the only disinfectants capable of killing harmful pathogens, while still maintaining water quality. 

There are a number of theories on how chlorine and chlorine-based compounds work to disinfect water. Scientific American highlights this possible sequence of events: 

  • Chloramine disrupts the cell wall barrier of the cells of microorganisms;
  • The cells release vital cellular constituents, which are needed for the microbes’ survival;
  • As a result of this alteration, membrane-associated functions are terminated; and
  • The cell is no longer able to perform cellular functions, and can no longer replicate.

Chloramine disinfection is usually the seventh stage in the water treatment process. By the time of disinfection, water has been collected, screened and strained, and undergone processes including coagulation and flocculation, clarification and sedimentation, and filtration. Chloramination is the last treatment stage before water is stored and distributed.

A History of Chloramine Water Treatment

According to the CDC, chloramine has been used for water treatment since 1929. Cleveland, Ohio; Springfield, Illinois; and Michigan were among the first places to replace chlorine with chloramine in the water disinfection process. 

An EPA survey carried out in 1998 found that at the time, chloramine-disinfected water was being delivered to around 68 million Americans. This number is steadily increasing as major cities like Washington, D.C, and San Francisco have switched to chloramine for water treatment. 

What Makes Chloramine Different from Chlorine?

Chlorine and chloramine are structurally different. Chlorine is made from chlorine atoms, while chloramine combines chlorine and ammonia. 

You might wonder why chloramine has been introduced if chlorine and chloramine can both be used for the same purpose. However, there are some notable differences between chlorine and chloramine: 

  • Chloramine is less volatile. This is the major difference between chloramine and chlorine. Volatile substances, like chlorine, easily evaporate at room temperatures. Being less volatile than chlorine, chloramine stays in water longer, providing longer-lasting protection. 
  • Chloramine has a less distinct taste and odor. While chlorine can have a bleach-like smell and taste in water, chloramine is less potent. 
  • Chloramine is more corrosive. Compared to chlorine-treated water, water treated with chloramine can have more of a corrosive effect on pipes and plumbing. 

Unless you have a very sensitive palette, you probably will not be able to tell the difference between chlorine and chloramine by smelling or tasting your water. The easiest way to know which chemical disinfectant your water contains is to look at your Water Quality Report. Alternatively, contact your municipality directly. 

Why Have So Many States Switched to Chloramine Use?

Because the EPA deems chloramine a safe disinfectant, all water treatment plants in the country are allowed to use this chemical compound to disinfect drinking water. There are benefits and drawbacks to using both chlorine and chloramine as disinfectants, but, with chloramine having more benefits, this disinfectant is more popular today. 

The biggest issue with chlorine is that it produces traces of dangerous chemicals, known as disinfection byproducts, as it travels to our homes. This is especially likely if the water that has been treated contained high quantities of microorganisms that reacted with chlorine. Disinfection byproducts include chlorate and benzene, which both have known health effects with long-term exposure. 

Additionally, chlorine is used up at a faster rate, which means that, in water that’s particularly badly contaminated, there may not be enough chlorine to kill all the microorganisms before the water needs to be used for drinking. 

Chloramine does not release disinfection byproducts and lingers in water for longer, which makes it more popular in water utilities. 

The Pros and Cons of Chloramine Use

To summarize the advantages and disadvantages of using chloramine as a disinfectant: 

Pros of Chloramine Use: 

  • Chloramine is more stable, remaining in water for longer and providing longer-lasting protection against harmful microorganisms.
  • Because chloramine has a low oxidation potential, it does not produce concerning levels of disinfection byproducts. 
  • Chloramine is easy to use and inexpensive in large-scale applications. 
  • Chloramine does not have such a strong chemical taste or odor in water. 

Cons of Chloramine Use: 

  • To make monochloramine on-site, chlorine gas or hypochlorite are needed, and safety measures must be imposed.
  • Additional safety precautions are needed to prevent ammonia from vaporizing and to stop nitrogen trichloride from forming. 
  • Chloramine is weaker than chlorine as a disinfectant against viruses and cysts, and requires longer contact times with water to produce the same outcomes. 
  • Chloramine is more corrosive to metal pipes.

The Bottom Line

Chloramine is a safe, effective disinfectant that is becoming more and more popular as a chloramine alternative in municipal water treatment. In low levels, chloramine does not have any known health effects. However, like chlorine, you may still taste chloramine in your water. 

Although chloramine is essential to maintain safe, pathogen-free water as it travels underground to our homes, this chemical compound can be safely removed from water with an at-home filtration system before drinking. 

About the Author

Brian Campbell

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