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How Safe Is Water Chlorination?

Most municipalities rely on water chlorination for safe tap water. New research suggests that chlorine may form dangerous by-products with other compounds.
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Most Americans take water chlorination for granted. This is how the majority of municipalities ensure that their tap water won’t make people sick. After all, chlorine is very effective at killing waterborne microbes. That is why public health officials view chlorination as one of the most important tools in preventing infection. It is critical for protecting people from diseases such as cholera or typhoid.

Does Water Chlorination Have Any Downsides?

A new study suggests that chlorine forms toxic chemicals in the presence of phenols (Environmental Science and Technology, Jan. 6, 2020). Such phenols are common in water supplies. The source may be personal care products or pharmaceuticals that end up in waste water and may be incompletely removed during purification. Plastic water pipes may also shed phenols into drinking water.

The authors point out that

“chlorine reacts with organic and inorganic water constituents to produce a variety of disinfection by-products (DBPs) that pose potential health risks.”

They note that over 700 DBPs have been identified, including some known carcinogens. The researchers found that phenols from consumer products interact with chlorine to cause some of these potentially toxic chemicals.

How Important Is Chlorine?

Do we really need water chlorination? Although it is a good way to guard against water-borne infections, chlorination is not the only technique that is effective. European public health officials often use other measures including filtration, ozone or ultraviolet treatment to purify water. There is no indication that people drinking such water are more likely to suffer illness as a consequence.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
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  • Prasse C et al, "Chlorination of phenols revisited: Unexpected formation of α,β-unsaturated C4-dicarbonyl ring cleavage products." Environmental Science and Technology, Jan. 6, 2020. DOI: 10.1021/acs.est.9b04926
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Ever since I moved to the town I currently live in, I started buying gallon jugs of purified water for cooking and drinking. I add mega-mag to the jugs, magnesium and trace minerals. Not perfect, but better than ingesting the Hydrofluorosilicic acid they pour into our water, for which there is NO justification. The Chlorine does have some justification, but we are by-passing both with the jugs of water. Does not help us when we shower, or boil pasta or potatoes, etc. For some reason American municipalities seem hell-bent on poisoning us, while Europeans seem to be trying to preserve the health of citizens. For the most part they use neither chlorine nor industrial waste containing fluorides in the public water supply. And virtue-signaling all the way. Why this is so is not at all clear to me.

What’s the history behind widespread chlorine injection into the water supply in the USA and why does the practice persist if alternative treatments are available? Is this another case of government subsidy gone awry?

I might suggest that if you are concerned about the potentially toxic effects of chlorination, you consider installing a point-of-use charcoal filter under the sink in series with the cold water supply line, i.e. the kitchen.

It is easily installed, and the purchase price including extra filters and additional supply lines was,for me, about $100.

Use that tap for drinking and cooking.

Btw, the filter removes other chemicals rendering the tap water clear and very tasty.

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