Brief History of Chlorine

Chlorine (Cl2)

Federal regulation of drinking water quality began in 1914, when the U.S. Public Health Service set standards for the bacteriological quality of drinking water. The standards applied only to water systems which provided drinking water to interstate carriers like ships and trains, and only applied to contaminants capable of causing contagious disease. The Public Health Service revised and expanded these standards in 1925, 1946, and 1962. The 1962 standards, regulating 28 substances, were the most comprehensive federal drinking water standards in existence before the Safe Drinking Water Act of 1974. With minor modifications, all 50 states adopted the Public Health Service standards either as regulations or as guidelines for all of the public water systems in their jurisdiction.

By the late 1960s it became apparent that the aesthetic problems, pathogens, and chemicals identified by the Public Health Service were not the only drinking water quality concerns. Industrial and agricultural advances and the creation of new man-made chemicals also had negative impacts on the environment and public health. Many of these new chemicals were finding their way into water supplies through factory discharges, street and farm field runoff, and leaking underground storage and disposal tanks. Although treatment techniques such as aeration, flocculation, and granular activated carbon adsorption (for removal of organic contaminants) existed at the time, they were either under utilized by water systems or ineffective at removing some new contaminants.

Health concerns spurred the federal government to conduct several studies on the nation’s drinking water supply. One of the most telling was a water system survey conducted by the Public Health Service in 1969 which showed that only 60 percent of the systems surveyed delivered water that met all the Public Health Service standards. Over half of the treatment facilities surveyed had major deficiencies involving disinfection, clarification, or pressure in the distribution system (the pipes that carry water from the treatment plant to buildings), or combinations of these deficiencies. Small systems, especially those with fewer than 500 customers, had the most deficiencies. A study in 1972 found 36 chemicals in treated water taken from treatment plants that drew water from the Mississippi River in Louisiana. As a result of these and other studies, new legislative proposals for a federal safe drinking water law were introduced and debated in Congress in 1973.

Chemical contamination of water supplies was only one of many environmental and health issues that gained the attention of Congress and the public in the early 1970s. This increased awareness eventually led to the passage of several federal environmental and health laws, one of which was the Safe Drinking Water Act of 1974. That law, with significant amendments in 1986 and 1996, is administered today by the U.S. Environmental Protection Agency’s Office of Ground Water and Drinking Water (EPA) and its partners.

Since the passage of the original Safe Drinking Water Act, the number of water systems applying some type of treatment to their water has increased. According to several EPA surveys, from 1976 to 1995, the percentage of small and medium community water systems (systems serving people year-round) that treat their water has steadily increased. For example, in 1976 only 33 percent of systems serving fewer than 100 people provided treatment. By 1995, that number had risen to 69 percent.

Since their establishment in the early 1900s, most large urban systems have always provided some treatment, as they draw their water from surface sources (rivers, lakes, and reservoirs) which are more susceptible to pollution. Larger systems also have the customer base to provide the funds needed to install and improve treatment equipment. Because distribution systems have extended to serve a growing population (as people have moved from concentrated urban areas to more suburban areas), additional disinfection has been required to keep water safe until it is delivered to all customers.

Today, filtration and chlorination remain effective treatment techniques for protecting U.S. water supplies from harmful microbes, although additional advances in disinfection have been made over the years. In the 1970s and 1980s, improvements were made in membrane development for reverse osmosis filtration and other treatment techniques such as ozonation. Some treatment advancements have been driven by the discovery of chlorine-resistant pathogens in drinking water that can cause illnesses like hepatitis, gastroenteritis, Legionnaire’s Disease, and cryptosporidiosis. Other advancements resulted from the need to remove more and more chemicals found in sources of drinking water.

According to a 1995 EPA survey, approximately 64 percent of community ground water and surface water systems disinfect their water with chlorine. Almost all of the remaining surface water systems, and some of the remaining ground water systems, use another type of disinfectant, such as ozone or chloramine.

Many of the treatment techniques used today by drinking water plants include methods that have been used for hundreds and even thousands of years (see the diagram below). However, newer treatment techniques (e.g., reverse osmosis and granular activated carbon) are also being employed by some modern drinking water plants.

Source: (Full article:The History of Drinking Water Treatment)


Chlorine the Good, Bad and Concerns

Following are statements and quotes from a variety of sources

The Good news

is that chlorine has done a good job in killing most microorganisms in the water.

In fact, the United States has one of the safest water supplies in the world. Without chlorine (or some other form of water disinfection treatment), millions of people would die from devastating infections such as cholera, salmonella, and others.

The Bad news

is that chlorine treatment does not absolutely ensure that by the time our drinking water comes out of our home faucet it is free of unhealthy microorganisms.

Dangerous bacteria (such as e-coli and coliform) are still found in chlorinated tap water on occasion. When this happens it is primarily due to problems related to the treatment system itself or to the transport of the water to our homes. Relying on chlorine disinfection alone is a false guarantee that the water from your tap is safe to drink.

Even minimal exposure to these types of bacteria can cause symptoms similar to the flu, such as headaches, diarrhea, cramps, nausea or vomiting.

The Concerns

Relitive to drinking chlorinated water has only recently been documented. It has to do with the long-term health effects of chlorine and its disinfection by-products (DBPs).

Studies have found is that chlorine itself is not the main problem; rather it has to do with what happens when the chlorine mixes with any type of organic matter in the water. In the 1970s scientists discovered that when chlorine is added to water, it forms Trihalomethanes (THMs), one of which is chloroform. THMs increase the production of free radicals in the body and are highly carcinogenic (cancer causing).

Chlorine and THMS have been linked to various types of cancer, kidney and liver damage, immune system dysfunction, disorders of the nervous system, hardening of the arteries, and birth defects.

The Affects

Unfortunately, we are learning the hard way that our attempts to prevent illness by adding chlorine in drinking water has contributed to another problem—the increase of cancer and heart disease.

Here’s what the experts have to say:

“Cancer risk among people using chlorinated water is as much as 93 percent higher than among those whose water does not contain chlorine,” according to the U.S. Council of Environmental Quality.

According to the,“One common factor among women with breast cancer is that they all have 50 to 60 percent higher levels of these chlorination by-products (THMs) in their fat tissue than women without breast cancer . . .”

“Long-term drinking of chlorinated water appears to increase a person’s risk of developing bladder cancer as much as 80 percent,” as documented in a study published in the Journal of the National Cancer Institute. Some 45,000 Americans are diagnosed every year with bladder cancer.

“The drinking of chlorinated water has finally been officially linked to an increased incidence of colon cancer. An epidemiologist at Oak Ridge Associated Universities completed a study of colon cancer victims and non-cancer patients and concluded that the drinking of chlorinated water for 15 years or more was conducive to a high rate of colon cancer,” according to Health Freedom News, January/February 1987.

“Scientists found there was a higher incidence of cancer of the esophagus, rectum, breast, and larynx and of Hodgkins Disease among those drinking chlorinated surface waters.”
“Volatile organics can evaporate from water in a shower or bath.”
“Conservative calculations indicate that inhalation exposures can be as significant as exposure from drinking the water, that is, one can be exposed to just as much by inhalation during a shower as by drinking 2 liters of water a day.”

“People who shower frequently could be exposed through ingestion, inhalation and/or dermal absorption.”

IS YOUR WATER SAFE TO DRINK? Consumer Reports Books, Chlorinated Drinking Water Linked to Cancer

“Showering is suspected as the primary cause of elevated levels of chloroform in nearly every home because of the chlorine in the water.”
Dr. Lance Wallace


Aquarium enthusiasts know that when filling an aquarium with tap water the first thing that needs to be done is to use a de-chlorinator, chlorine neutralizer or chlorine remover. This is critical to the survival of the fish because the fish will not be able to survive in chlorinated water!