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How Much Chlorine is in Tap Water?

*Reviewed by Ken Christopher, Senior Vice President at Rayne Dealership Corporation

Though we need water every day of our life, most of us don’t think too deeply about the journey of our tap water before it pours from our faucet. In the past, access to clean drinking water could literally be a life and death struggle. Today, we simply have to create an account with the local community water supplier.

Not only is access to water significantly easier than it was in the past, but the water we drink is also better. A key reason for this is disinfection. Disinfection of our water supply is an incredibly important component of our national public health system, and the backbone of water disinfection is the use of the chemical additive chlorine or chloramine. But how much  is in tap water? How does it  affect your water? Is chlorinated water safe to drink? The answers to these questions and others that you may have about chlorine/chloramine in your tap water are crucial for making an informed decision about what types and levels of contaminants, disinfectants and other substances you are comfortable having in your drinking water supply.

Why is Chlorine Added to Drinking Water?

Chlorine is added to drinking water to protect against harmful microbes and waterborne diseases. Treating drinking water is not a new process, but the transition to chlorination of water sources represents an important shift that had immense public health consequences. Chlorinated tap water typically has a high chlorine level and can even taste similar to pool water. Without a carbon filter or ascorbic acid, the free chlorine level in most city treated water may be higher than it should be for healthy water consumption.

While early treatment of drinking water dates back to at least 4000 B.C., it was primarily intended to address unpleasant tastes or smells in the water. It wasn’t until the understanding of germ theory emerged in the late 19th century that it became clear that microbes could spread disease through the water. Early efforts are reducing the number of microbes in water mapped closely to existing efforts to reduce turbidity in water, which is the cloudy appearance water can take on from suspended particles. Filtration was accomplished by passing water slowly through the sand, but it became clear that this filtration process didn’t remove all disease-causing microbes.

Some of the most destructive and lethal pathogens, including dysentery, cholera and typhoid were transmitted through water prior to the adoption of chlorination. The first city to add chlorine to drinking water was Jersey City in 1908, and the use of chlorine to treat drinking water subsequently spread throughout the United States as it became clear that it helped reduce the transmission of waterborne disease.

How Effective is Chlorination?

Chlorination is thought to be the primary way that outbreaks of waterborne diseases were reduced in the United States. For example, prior to chlorine treatment of drinking water systems, typhoid fever was responsible for a comparable death rate to modern automobile accidents. Roughly 25 in 100,000 people were killed every year in the United States from typhoid fever. Following the widespread adoption of chlorination, deaths from typhoid fever were nearly eliminated. The same is true for a wide range of other waterborne contaminants, including diseases caused by waterborne viruses, bacteria and protozoa.

Despite its effectiveness, chlorine isn’t the only substance used in water treatment. Many treatment facilities may use the chemical chloramine as well. Chloramine is usually used as an alternative to chlorination. Specifically, monochloramine is used to disinfect water, and shouldn’t be confused with dichloramine or trichloramine which are often used in indoor swimming pools. Chloramine treatment has been around since 1929, and many millions of Americans drink water that has been treated with chloramine.

Both chlorine and chloramine have drawbacks. One of the main drawbacks of chlorine in tap water is that it doesn’t last for a long period of time. Since it is necessary to ensure a sufficient level of disinfectant remains in the water after it has been treated but before it arrives at your tap, some community water suppliers turn to chloramine which is longer-lasting to provide ongoing protection against microbes.

Perhaps the most significant drawback of chlorine, chloramine, and other disinfection processes is that they produce disinfection byproducts in the water when they come into contact with organic material. These byproducts have potential health impacts that we’ll discuss in greater detail in a subsequent section.

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Safe Levels of Chlorine in Drinking Water

Though chlorination has proven to be a powerful tool for ensuring many people have safe access to drinking water in the United States, it isn’t without drawbacks or health risks. Like other contaminants in drinking water, the Environmental Protection Agency (EPA) has determined threshold values, known as the Maximum Residual Disinfectant Level (MRDL), for how much chlorine can be in drinking water while still being considered safe for consumption. Currently, this level is less than 4 milligrams per liter (mg/L) or 4 parts per million (ppm).

It is important to recognize that the levels set by the EPA are broad guidelines that may not be ideal for everyone. Some individuals have sensitivities to certain chemicals, including chlorine, which may lead to health concerns. Chlorine in water is also problematic if it’s used during dialysis treatment, which requires large amounts of water to clean waste out of the dialysis patient’s blood.

The levels of chlorine or chloramine in drinking water vary depending on a variety of factors. An easy way to get a basic understanding of the levels of disinfectants in your drinking water is to check the most recent water quality report published by your community water supplier. Most community water suppliers publish these reports on an annual or semi-annual basis, and while they don’t tell you how much disinfectant is in your water at any given time they will give you a general understanding of how your water supplier is treating the water that is piped to your home and what the levels of residual disinfectant in the water are. For example, this 2018 water quality report published by the City of San Diego shows that residual levels of chloramine exist in san diego tap water at an average of 1.9 ppm and range from undetectable levels to 3.4 ppm.

Disinfection Byproducts

Any discussion of chlorine levels in water must also include information about disinfection byproducts (DBPs) and their risks. Treatment using chlorine, chloramine, ozone, or nearly any other disinfection method used on a large scale will produce byproducts in the water. From a public health perspective, the risks that disinfectants and their by-products pose must be weighed against the obvious public health benefit that disinfection offers.

DBPs form when disinfectants like chlorine and chloramine are added to water and react with organic materials in the water. The most common DBPs are:

  • Trihalomethanes (TTHMs)
  • Haloacetic acids (HAA5)
  • Chlorite
  • Chlorate
  • Bromate

There are known health risks associated with the consumption of DBPs. For example, THMs are considered possibly carcinogenic. These compounds form when free chlorine comes into contact with organic material in water. Common THMs include chloroform, bromodichloromethane, bromoform and dibromochloromethane.

Reducing Levels of Disinfectants and Disinfection Byproducts

While disinfectants like chlorine and chloramine are a valuable component of our modern community water supplies, there are some very good reasons for removing these contaminants from your water once it arrives at your home. Though consumption of disinfectants and their byproducts are considered safer than potentially contracting a waterborne disease, they may pose a health risk when consumed over time. Additionally, disinfectants and their byproducts alter the taste and smell of the water you are consuming. Removing these substances from your water can ensure you limit exposure to contaminants while also enhancing the taste and smell of your water. If the water has arrived safely at your home, there is no need to maintain chlorine or chloramine treatment. The proper water filter system for your water source can remove the chlorine taste, ammonia, chlorine, and other disinfectants present in your drinking water supply.

Curious about how to get chlorine out of water? The most effective form of filtration for removing disinfectants and their byproducts is by using an activated carbon filter. Activated carbon is a special type of carbon that has been treated with heat or oxygen to expand its surface area. Once water enters an activated carbon system, disinfectants like chlorine or its byproducts are trapped on the surface of the carbon through a process known as adhesion.

Activated carbon filtration is also great for removing other contaminants that may alter the smell or taste of your water, such as volatile organic compounds (VOCs). Filtration systems utilizing activated carbon come in different forms, including systems that filter all of the water in your home or smaller systems that provide filtered water at a specific tap. To understand the best water filtration system for you, contact Rayne Water so that one of our water quality experts can assess your needs and find the right system for you.

Home water filtration systems are also an excellent way to save money on your drinking water. Many people consume bottled water because they prefer the taste, without realizing that they can achieve the same great tasting water with their own filtration system. Though some bottled water such as alkaline water is marketed for its perceived health benefits, it is often better for your long-term health to limit your exposure to contaminants. If you’re wondering, “is alkaline water good for you?”, check out our recent article on the subject to explore the topic in greater detail. You may be surprised to find that the pH of tap water has far less of an impact on health than ensuring your drinking water is free of contaminants.

Closing Thoughts

Chlorine is the most common chemical used by water suppliers for disinfection in the United States. While chlorine provides an enormous public health benefit, it isn’t without drawbacks. Chlorine alters the smell and taste of the water we drink and bathe with. When chlorine is added to water it reacts with organic material to form disinfection byproducts, which may increase the risk of certain cancers when consumed over long periods of time.

On a national scale, the health risks that disinfectants like chlorine and their byproducts pose to public health are small compared to the benefit that they provide. However, at an individual level it is up to us to determine if we are comfortable with the risk that being exposed to these chemicals and their byproducts carry.

Thankfully there are effective filtration systems for removing disinfectants, their byproducts, and a wide range of other contaminants that may remain in the water coming out of your tap. To learn about the best water treatment systems for dealing with chlorine, chloramines, and other chemicals, contact Rayne today. One of our water quality experts will help you find the best water treatment system for you. Whether you’re looking for water treatment for your home or business, our expert staff at Rayne Water have got you covered!



Expert Reviewer – Ken Christopher