Everyone who’s ever been around a swimming pool recognizes the smell of chlorine. This chemical is also used in drinking water to remove the microorganisms that, throughout history, have caused millions of incidents of illness and death. Chlorination of our water supplies is a necessary step to greatly reduce the risk of disease, but it comes with possible adverse effects. Many people want to ensure that their families are exposed to as little chlorine as possible.
Why Chlorine Started to Be Added to Public Water Supplies
Before chlorine was found effective as a water disinfectant, city water supplies were responsible for causing one epidemic illness after another:
- 1849: Dysentery, widespread in the U.S.
- 1854: Cholera in London, UK
- 1982: Cholera in Hamburg, Germany
- 1897: Typhoid in Maidstone, Kent, UK
- 1905: Typhoid in Lincoln, UK
- 1910: Typhoid in Chicago, Illinois
- 1916: Dysentery in New York City
In 1908, Jersey City began adding chlorine to their city water supplies to kill microorganisms that cause serious or even fatal diseases. After this, more cities and countries around the world began adding chlorine to water supplies and these illnesses began to drop.
A Wide Variety of Illnesses Can Be Prevented Through Chlorination
Chlorination at the right concentration can prevent these illnesses:
- Typhoid fever
- Cholera
- Amœbic dysentery
- Bacterial gastroenteritis
- Shigellosis
- Salmonellosis
- Campylobacter enteritis
- Yersinia enteritis
- Pseudomonas infections
- Schistosomiasis
- Giardiasis
- Various viral diseases, such as hepatitis A
While many people have understandable concerns about the chlorine in public water supplies, or the use of chlorine to disinfect private water wells, chlorine has played an important role in protecting the health of humans and animals.
The Difference Between Chlorine and Chloramines
Disinfection with chloramines is an alternative to using straight chlorine. Chloramines are a group of chemicals that combine chlorine and ammonia. The specific type of chloramine used for water disinfection is called monochloramine. While chlorine tends to dissipate quickly once it is added to water, chloramines last longer and so can disinfect water farther from the point that chemicals are added. Monochloramine also produces fewer by-products than straight chlorine does—some of these by-products may be harmful. Many water companies switch from one disinfectant to the other on a specific schedule.
Dangerous By-Products of Chlorination That Can Cause Health Problems
It was already noted that monochloramine produces fewer by-products of disinfection than chlorine. What does this mean? It means that once either of these disinfectants are added to the water, they interact with substances already in the water and this interaction produces other substances that are sometimes toxic.
In the case of chlorine and drinking water, the chemical interacts with the following substances to form hazardous by-products:
- Decaying plant material
- Acids in the soil that result from the breakdown of organic matter
- Pesticides
- Algae
- Biofilms from fungi, algae, bacteria and other microorganisms
These by-products are referred to as trihalomethanes (THMs). There are four of these THMs commonly found in water that has been chlorinated. They are:
- Chloroform
- Bromodichloromethane
- Dibromochloromethane
- Bromoform
Contact with these chemicals has been linked with health concerns, such as an increased risk of cancer, harm to developing fetuses and children, and changes to human DNA. The International Agency for Research on Cancer has classified these chemicals as “probable human carcinogens” and has linked THMs to bladder cancer risk. There is a possible increased risk of endometrial cancer as well. Bromoform is also a central nervous system depressant which means it can affect brain functions as well as harm the kidneys and liver.
How Much Chlorine in Your Drinking Water is Acceptable?
According to federal and global health agencies, as long as chlorine levels stay low, drinking water that has been disinfected with this chemical is safe to drink. The Environmental Protection Agency has set a limit of 4 milligrams per liter of water as the maximum amount of chlorine in water that is safe to drink. This is equivalent to 4 parts per million of chlorine to water. The guideline from the World Health Organization is 5 parts per million.
It’s possible for toxicity from chlorine consumption to cause nausea, vomiting, and throat and stomach irritation but this is ordinarily due to consumption of swimming pool water with higher levels of chlorine. Some people may be sensitive to the chlorine in their drinking water and suffer from worsened asthmas or eczema.
Most people become accustomed to the small amounts of chlorine in drinking water and do not suffer significant ill effects.
Problems in Chlorination Can Lead to Excessively High Chlorine in Water
It’s not that uncommon for municipal water services to have problems with their chlorination systems. At these times, the chlorine levels in water distributed to their customers can be high enough to cause health problems.
For example:
- Jacksonville, Florida in 2019. Routine maintenance caused a normal release of chlorine into the water but some people received an excessive amount in their supply.
- Baltimore, Maryland in 2021. An equipment malfunction spiked the chlorine levels in the water. Customers were warned not to use the water.
- Las Vegas, New Mexico in 2022. Chlorination was increased in response to a concern about water contamination. A “Do Not Use” warning was issued for drinking or bathing.
- Longview, Texas in 2023. Again, there was a concern about detected or suspected contamination. Chlorine levels were too high and a similar warning was issued.
Excessive Chlorine Levels Are Possible After Private Well Disinfection
When a private well owner disinfects their own well, the disinfection instructions always call for the well to be thoroughly flushed until there is no smell of chlorine remaining. The time required to eliminate a chlorine disinfectant can range from a few hours to several days. The time required depends on the size of the well and the volume of water that can be flushed out by leaving all taps open.
Careful well owners should conduct a test of their water well after disinfection to determine that chlorine levels are below 4 parts per million. A follow-up test like this can also confirm that disinfection was completely successful in removing pathogens like E. coli, Salmonella, Legionella, Campylobacter and Vibrio cholerae.
An Additional Problem Caused by Chlorine in City or Well Water
Chlorine is a caustic substance. If you’ve ever spilled chlorine bleach in your clothes, you’ve seen this for yourself. It burns skin and fabric alike. Chlorine also corrodes metal pipes, fixtures and appliances over time. Corrosion from chlorine levels that are too high can lead to the need to repair or replace plumbing fixtures or appliances.
It is possible to reduce the corrosion problem by using materials that are less susceptible to this corrosion such as stainless steel or plastics, or by removing chlorine from the water with a whole-house filtration system.
For City Dwellers: Finding Out About Chlorine and THMs in Your Water
Those relying on municipal water may want to find out their levels of chlorine or THMs. A professional water testing company like ETR Laboratories can provide any concerned water user with a fast and accurate test of chlorine, THMs and hundreds of other toxins that are not desirable in a water supply.
The only problem with testing a municipal water supply is that the chemical levels in the water may vary from day to day. They also vary from one part of a city to another. Municipalities monitor their water on a constant basis because they have the equipment to do so. Residents can only test water quality at a specific location and time.
Testing a water supply can provide a snapshot of what contaminants are typically in a water supply. This can guide a water user as they choose a whole-house or under-sink filter to remove contaminants they don’t want their family exposed to.
How to Test Your Water for Its Chlorine Content
There are inexpensive water testing kits for drinking water and swimming pool water that provide a guide to the quantity of chlorine in the water. Kits for drinking water contain test strips that are dipped into water samples. By comparing the color of the small pads on the test strip to a color guide, it’s possible to get an idea of how much chlorine is in the water.
This kind of test is an approximate guide but is not a scientific test. To determine if chlorine actually does exceed 4 parts per million, it’s necessary to enlist the services of a professional testing lab.
There are several other types of test kits for detecting chlorine or THMs in water but they require specialized equipment and are usually only found in professional laboratories.
How to Remove Chlorine From Your Drinking Water
When removing chlorine from drinking water, it’s also advisable to remove the THMs or disinfection by-products from the water. After all, they can be just as harmful or more so than chlorine. When you are thinking about your family’s exposure to chlorine or THMs, remember that they can be exposed to these chemicals through drinking, cooking, showering or bathing. These chemicals can be released into the air when the water is heated for cooking or during showering and bathing.
An activated carbon or reverse osmosis filter for all the water coming into the home can be effective in removing chlorine, chloroform, bromodichloromethane, dibromochloromethane and bromoform from household water. These systems are available as under-sink or whole-house systems.
If a large system is out of reach financially, smaller filters can help. These are called Point of Use filters. They can be installed in your shower, bath or washing machine. They can even be obtained in the form of water bottles that filter out chemicals on the fly.
Keeping Your Family Safe from Both Illness and Chemicals
Chlorine is necessary in municipal water supplies to prevent the long lists of diseases that appear above. A regular schedule of disinfection of private water wells is necessary to keep these household wells safe for the whole family plus their pets.
There are certain situations that call for greater than usual care in monitoring what’s in your water. If these situations exist in a household, the purer the water, the greater the safety:
- Pregnancy: Some chemicals and contaminants can interfere with fetal development.
- Nursing: Many contaminants are transmitted to an infant during nursing. They can slow a baby’s development and growth.
- Children: Children drink more water relative to their body weights and so have a proportionally higher exposure to drinking water. Some contaminants interfere with a child’s growth, or physical or mental development.
- Cancer treatment: Some cancer treatments suppress the immune system. This can weaken a person’s ability to detoxify water contaminants.
- Organ transplant: The medications taken to keep a body from rejecting a donated organ also suppress the immune system. This leaves a person vulnerable to pathogens like Cryptosporidium, Giardia, and bacterial coliform.
- Being immunocompromised: Conditions like HIV and AIDS impair the immune system, as does smoking and aging. Some medications also lower immunity. Being immunocompromised not only leaves a person vulnerable to infection from microorganisms, but also to the toxic effects of chemical or mineral contamination.
The Correct Use of Professional Water Tests to Protect Your Family
For the homeowner who wants the best protection for their family, professional water tests are excellent tools. Fast, accurate water tests from a professional lab provide guidance in designing the right water filtration system for the whole house or for parts of it.
ETR Laboratories has helped tens of thousands of families monitor their private water well or their municipal water supplies. ETR Laboratories can help you choose the right water test for your situation. Choosing a very specific test for that chemical will help you pinpoint the chlorine content of your well. If you need help or advice choosing the best water test for your situation, call us at (866) 233-7982.