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Can Chlorine in Drinking Water Cause Cancer?

Updated: Jun 24, 2023

Adding chlorine to our Drinking Water has been around for some time; there are several reasons drinking water is chlorinated.

Chlorine Skull

First, chlorine inhibits the growth of bacteria and other types of pathogens, including algae in our drinking water supply, pools, and spas.

However, the chlorine will not destroy or kill pathogens such as microorganisms like giardia or cryptosporidium. These organisms are resistant to most commonly used water disinfectants, including chlorine.

Nonetheless, chlorine appears to help prevent the most common water-borne diseases, like cholera. These plagued the world and still does in many Third World countries today; however, using chlorine to disinfect comes with a price.

Moreover, what happens to chlorine when it makes contact with organic elements in the water supply? First, residual chlorine generally emits an odour as it gases off drinking water. In Sydney, it is prevalent on rainy days.

However, if chlorine is added to drinking water to control and kill bacteria in the water, will it damage or affect our gut health.

Bacteria Closeup

One such study published in July 2015 confirms that the consumption of chlorinated water can lead to tumours in mice. They were mainly forming tumours and polyps in the colon and the small intestinal tract. However, the effects of chlorine vary by the chlorine concentration in the water.

The study also found that mice who consumed chlorinated water in higher concentrations for 40 days had a greater overall body weight than those who consumed lower chlorine concentrations.

However, this was more so the case for mice with a specific chromosomal instability. Therefore, those mice that already had a genetic disposition to cancer due to chromosomal instability were more likely to develop cancer, such as polyps or tumours in the intestinal tract.

Eczema Example

Chlorine, Can It Affect our Skin, the Biggest Organ?

Chlorine is an oxidising agent designed to kill pathogens at low concentrations. However, according to the 2015 Study, chlorine can kill bacteria in the gut or cause an imbalance, affecting the overall health of the intestinal tract.

Chlorine will likewise affect the balance of healthy bacteria on our skin, and it tends to strip our skin and hair of healthy oils. However, this will dry out the skin, making it itchy and the hair dry and brittle.

Dry and itchy skin stripped of its natural oils will cause existing skin conditions such as dry and itchy skin conditions to flare up, like eczema. However, not all types of eczema are affected, and this will vary from person to person.

You may want to read our article: Fluoride: is it safe?

Digestive Diagram

Can Chlorine Be Carcinogenic or Cancer-Causing?

However, water disinfection is required in our water supply to provide a safe drinking water supply, free from water-borne diseases.

Whether chlorine is the only solution is highly debatable, especially as many European countries have removed the practice of chlorinating the water with no ill health effects.

In the early 1970s, a Dutch researcher discovered the presence of Chloroform, a type of Disinfectant byproduct or (DBP). Although scientists have discovered many DBP years later, almost all DBP are probable carcinogens, according to the World Health Organisation (WHO).

These byproducts come about when chlorine reacts with natural organic matter found in the water supply.

Chlorine Skull


Chlorine can have detrimental health effects on the body. For example, it can dry out the skin and hair, in most cases making it uncomfortable for people with eczema. In addition, when organic matter makes contact with chlorine, it forms disinfectant byproducts or DBPs.

DBPs are cancer-causing agents, as listed by the WHO. Furthermore, studies in mice have shown that chlorinated water can affect those most susceptible to cancer, infants, and those with immunocompromised individuals.

Can drinking water be delivered without disinfectants like chlorine and still be safe
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Chlorinated water study 2015 tumour cancer
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