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Why Is Fluoride In Our Water?

There’s a public health reason why some authorities choose to put the mineral in water supplies.

Holly Large - Editorial Assistant

Holly Large

Holly Large - Editorial Assistant

Holly Large

Jr Copy Editor & Staff Writer

Holly is a graduate medical biochemist with an enthusiasm for making science interesting, fun and accessible.

Jr Copy Editor & Staff Writer

Edited by Laura Simmons
Laura Simmons - Editor and Staff Writer

Laura Simmons

Editor and Staff Writer

Laura is an editor and staff writer at IFLScience. She obtained her Master's in Experimental Neuroscience from Imperial College London.

Fact Checked by Francesca Benson

Francesca Benson

Copy Editor and Staff Writer

Francesca Benson is a Copy Editor and Staff Writer with a MSci in Biochemistry from the University of Birmingham.

hand holding a glass being filled up with water from a tap

Adding fluoride to water has helped to reduce tooth decay.

Image credit: r.classen/

First introduced in 1945, the practice of adding fluoride to public water supplies has since become a common practice in many places around the world. It doesn’t come without controversy, however – and though unfounded, it’s not unusual to come across concerns about its safety. But why is it put into water in the first place? And what makes it safe to do so?

What is fluoride?

Fluoride is a naturally occurring mineral that can be found in soil, water, and air, having been released from rocks. Many people will be familiar with it from its use in dental care products such as toothpaste and mouthwash, though it can also be found in some medications and, on rare occasions, dietary supplements.


Why was it first added to water?

In areas where fluoride in the water supply is naturally low, some authorities have added it in because, at recommended levels, it can help to prevent tooth decay – that’s why it’s found in a lot of toothpastes. It does this by helping to rebuild and strengthen tooth enamel, the hard, protective outer coating on our teeth. As a result, consistent contact with fluoride helps to keep teeth strong and stop pesky cavities from forming.

This relationship was first spotted back in the 1800s, and after research into fluoride’s safety in the 1930s and 40s, Grand Rapids, Michigan became the first city in the world to fluoridate its public water supply in 1945. Nearly 80 years later, it’s estimated that community water fluoridation helps to reduce tooth decay by 25 percent in children and adults.

Case in point: a city in Ontario, Canada, stopped adding fluoride into the water supply after 50 years, only to end up adding it back in 5 years later when the number of children with tooth decay or requiring urgent dental care shot up by 51 percent.

"For decades, low-level public water fluoridation has proven to have a dramatic effect on the rates of tooth decay, particularly in children," UK dentist and writer on dental health matters Ollie Jupes told IFLScience.


"Where fluoridation has been introduced, there is invariably a measurable difference in the rates of decay, compared to non-fluoridated areas. Decay rates in fluoridated areas can reduce by up to 25 percent. Removing fluoride from the water supply is madness."

Why do some people want to remove it?

Though a significant body of evidence supports the conclusion that adding fluoride to public water supplies is safe, there’s an equally plentiful supply of myths surrounding its use. As a result, there have recently been calls to ban fluoridation – and in the US, there’s currently an ongoing court battle to decide whether the Environmental Protection Agency (EPA) should do so due to concerns about its potential effects on child development.

However, according to the Centers for Disease Control and Prevention (CDC), “Scientists in the United States and around the world have studied the safety and benefits of fluoridated water for a century and have not found consistent and convincing evidence to link water fluoridation with any potential unwanted health effect other than dental fluorosis.”

Dental fluorosis can occur in children when they’re overexposed to fluoride during development. However, it isn’t harmful to their health; it causes white, sometimes brown, speckles on the teeth. It’s why fluoride often isn’t found in toothpastes made for young children.


Whilst it’s true that at high doses fluoride can present a health hazard – it’s been associated with a bone disease called skeletal fluorosis – that kind of level isn’t being added to public water supplies. In the US, the decision to fluoridate is down to individual states or local authorities, but if they choose to do so, there’s still a legal limit set and regulated by the EPA.

The bottom line is that, when used at the right levels, fluoride in public water supplies makes for safe drinking water, helping to reduce tooth decay and its knock-on effects. And while there might be one court case with people aiming to ban fluoridation, there’s another that shows many others are hoping for the opposite.

All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.  

The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.   


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