Explore Our Commercial Solutions

View Products

High-Quality Water, Anytime You Want It

Learn More

High Performance Materials, Innovative Designs

Learn More

Health Effects of Chlorine in Drinking Water

The U.S. General Accounting Office reports that there are serious deficiencies in water treatment plants in 75% of the states. More than 120 million people (about 50% of the population) may get unsafe water according to a study conducted by the Natural Resources Defense Council.

U.S. Health Officials estimate 900,000 people each year become ill – and possibly 900 die – from waterborne disease. The General Accounting Office estimates 66% of Safe Drinking Water Act violations aren’t reported.

The contamination of water is directly related to the degree of contamination of our environment. Rainwater flushes airborne pollution from the skies, and then washes over the land before running into the, rivers, aquifers, and lakes that supply our drinking water. Any and all chemicals generated by human activity can and will find their way into water supplies.

The chemical element chlorine is a corrosive, poisonous, greenish-yellow gas that has a suffocating odor and is 2 1/2 times heavier than air. Chlorine belongs to the group of elements called halogens. The halogens combine with metals to form compounds called halides. Chlorine is manufactured commercially by running an electric current through salt water. This process produces free chlorine, hydrogen, and sodium hydroxide. Chlorine is changed to its liquid form by compressing the gas, the resulting liquid is then shipped. Liquid chlorine is mixed into drinking water and swimming pools to destroy bacteria.

Until recently, concerns about drinking water focused on eliminating pathogens. The chlorine used to reduce the risk of infectious disease may account for a substantial portion of the cancer risk associated with drinking water. Chlorination of drinking water was a major factor in the reduction in the mortality rates associated with waterborne pathogen. The use of chlorine was believed to be safe.

This view is evident in an article, which appeared on the back page of the New York Times. The report stated that with the use of chlorine, “Any municipal water supply can be made as pure as mountain spring water. Chlorination destroys all animal and microbial life, leaving no trace of itself afterwards”. This statement reflected opinion accepted until recent years when halogenated organic compounds, such as chloroform, were identified in chlorinated drinking water supplies. Recent surveys show that these compounds are common in water supplies throughout the United States.

These concerns about cancer risks associated with chemical contamination from chlorination by-products have resulted in numerous epidemiological studies. These studies generally support the notion that by-products of chlorination are associated with increased cancer risks.

Chlorine is used to combat microbial contamination, but it can react with organic matter in the water and form dangerous, carcinogenic Trihalomethanes. According to Dr. Joseph M. Price, MD, in Moseby’s Medical Dictionary, “Chlorine is the greatest crippler and killer of modern times. It is an insidious poison”.

In a 1992 study that made front-page headlines, and was reported on in the July issue of the American Journal of Public Health researchers at the Medical College of Wisconsin in Milwaukee found that people who regularly drink tap water containing high levels of chlorine by-products have a greater risk of developing bladder and rectal cancers than people who drink unchlorinated water. The study estimates that about 9 percent of all bladder cancer and 18 percent of all rectal cancer cases are associated with long-term consumption of these by-products. This amounts to over 20,000 new cases each year.

Morris, with epidemiologist Thomas C. Chalmers and his colleagues at Harvard, used a new technique called meta-analysis to combine the results from the 10 best studies, yielding the new findings. They report that people drinking chlorinated water over long periods have a 21% increase in the risk of contracting bladder cancer and a 38% increase in the risk of rectal cancer. “I am quite convinced, based on this study, that there is an association between cancer and chlorinated water.”, says Robert D. Morris of the Medical College of Wisconsin in Milwaukee, who directed the new study.

About 90% of the population is drinking water which may contain hundreds of these Disinfection By-products (DBPs), also known as Trihalomethanes. The Environmental Protection Agency lowered the Maximum Contaminant Level for Disinfection By-products but it will be years before the new standard goes into effect.

In his book, Coronaries/Cholesterol/Chlorine, Joseph M. Price, MD presents startling evidence that Trihalomethanes, are the “prime causative agents of arteriosclerosis and its inevitable result, the heart attack or stroke.” These Trihalomethanes are created when the chlorine that is added to the municipal water supply reacts with organic matter such as leaves, twigs, or chemicals from agricultural runoff.

What The Experts Have To Say

Environmental Health News,
January 2025

“According to a recent meta-analysis published in Environmental Health Perspectives, drinking chlorinated water appears linked to a 33 percent increased risk of bladder cancer and a 15 percent increased risk of colorectal cancer. The study reviewed data from some 90,000 participants globally, and found elevated risks even when THM levels were below current regulatory limits.”

 

ScienceDaily (summary of the meta-analysis),
February 2025

“Disinfection by-products formed during chlorination—particularly trihalomethanes (THMs)—are associated with a higher risk of bladder and colorectal cancer, even at exposure levels below those considered safe by U.S. and EU standards.”

 

Nature Reviews Urology,
March 2025

“A systematic review highlighted that long-term exposure to THMs in drinking water is linked to increased bladder cancer risk, reinforcing concerns about the adequacy of current disinfection practices.”

 

Environmental Health Perspectives (EPA modeling study),
August 2022

“EPA researchers estimated that of the roughly 79,000 annual U.S. bladder cancer cases, around 8,000 might be attributable to exposure to chlorination disinfection by-products in public water systems.”

Additional Resources

Use the resources below to learn even more about the dangers of water contamination and the effects it has on the body.

Log in

You dont have an account yet? Register Now

Search

Wishlist

Your wishlist is empty.

Return to products

All Categories