10 Reasons Why Fluoride Is In The Tap Water We Drink

Almost 80% of people in the U.S. that get their water from a city water supply receive fluoridated water. Fluoride is thought to prevent around 25% of cavities in both adults and children, and is just one of the reasons why fluoride is in our tap water.

Fluoride occurs naturally in water from the erosion of minerals and rocks, but it is added to our tap water because of its health benefits. This article explains why fluoride is in our water, what the benefits are and the history of fluoride in our water.

Not all areas of the U.S. have fluoride in their water, so this post also provides information on which states and counties add fluoride to their tap water and the population it serves. Plus who the BEST and WORST states are when it comes to fluoridation and you can even check out how your own state fares.

10 Reasons Why Fluoride Is In Our Tap Water

Before we learn about the 10 reasons why fluoride is added to tap water, it’s important to know that fluoride does actually occur naturally – in minerals and rocks. Weathering and erosion of rocks allows the fluoride to enter our water supplies (both groundwater and surface water).

In fact, fluoride isn’t just in our water supplies, it’s in our rainwater and seawater. The concentration in seawater is far higher than that of our drinking water. The EPA recommendation is 0.7mg/L for tap water – but our oceans can have up to double that amount!

This is because the fluoride has accumulated over time from the breakdown of rocks.

So, while fluoride can be present in our drinking water naturally, community and public water systems also add it to the water before it reaches our tap. This is to make sure we are getting the right amount to reap the benefits!

Reasons why fluoride is in our tap water. Fluoride improves overall oral health by minimizing demineralization and tooth decay from bacteria, and increasing remineralization.
10 Reasons why fluoride is in our tap water. Data sourced from CDC, Harvard Health and EPA. Image created for Waterpurificationguide.com.

Ok, let’s delve into the 10 reasons why fluoride is in our tap water:

1. Keeps a low level of fluoride in saliva all day

When we drink tap water, the dissolved ions or minerals in it end up in our mouth, and can end up in our saliva. Fluoride is a dissolved ion. So, when we drink tap water that has fluoride in it, our saliva has an increased fluoride concentration.

In fact, a person living in an area with fluoridated water can have increases in the fluoride concentration of their saliva several times during a day. This is a good thing – keep reading to find out why!

2. Keeps teeth strong

Ok, time to get a bit science-y

The main component of tooth enamel is called hydroxyapatite.

Hydroxyapatite is made of calcium, phosphate and hydroxide (oxygen and hydrogen). When fluoride is in our saliva it means fluorapatite forms part of our tooth enamal instead of hydroxyapatite. I am sure you have already guessed it – but fluorapatite is made of fluoride! And calcium and phosphate too.

Why is that important for our teeth? Well, fluorapatite is much stronger than hydroxyapatite. So, by drinking tap water with fluoride in it, we are actually making our teeth stronger.

3. Reduces tooth decay (demineralization of tooth enamel)

Tooth decay is actually a disease! – A disease caused by bacteria growing on the surface of our teeth.

Bacteria (like Streptococcus mutans) make acids, which dissolve the main component of our tooth enamel – this is also known as demineralization of tooth enamel.

Fluoride in our plaque (the sticky, colorless film that constantly forms on our teeth) acts as a barrier or veneer on our teeth – and prevents the acid-producing bacteria from damaging our teeth and reduces tooth decay.

4. Prevents cavities

Cavities are holes in our teeth – places in our teeth that bacteria have permanently caused damage over months or even years. While tooth decay is just damage to our enamel (the outer layer of our teeth), cavities are holes that go through the enamel, the dentin (the layer under the enamel) and into the soft dental pulp below.

Fluoride makes our teeth strong and forms a barrier over our teeth, which prevents the bacteria from permanently damaging our teeth.

5. Reduces the need for fillings

Fillings are how dentists treat cavities. Dentists remove the decayed part of your tooth and fill it with an artificial substance – things like gold, silver amalgam, porcelain, or plastic and glass composite.

But, since drinking tap water with fluoride in it reduces cavities, this means it also reduces fillings.

6. Reduces the number of teeth removals

Teeth are removed when tooth decay is so bad that there is no way the tooth can be restored. The decay itself is horrible and typically painful. The teeth can even be black – yuck!

Up to two thirds of all teeth removals are due to cavities, according to an article published in the journal of Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology. That means just by drinking tap water with fluoride in it, up to two thirds of all teeth removals might be avoided.

7. Increases remineralization of tooth enamel

When we drink tap water with fluoride in it, the fluoride goes into the film that covers our teeth, which is also called plaque fluid. The fluoride combines with the components of any dissolved tooth enamel and forms a ‘fluorapatite-like’ (fluoride-calcium-phosphate) remineralized veneer (or covering) over the remaining surface of the tooth enamel.

This fluoride-calcium-phosphate covering is much more acid-resistant than the original tooth enamel and even forms more quickly than ordinary non-fluoride tooth enamel.

8. Reduces oral pain and suffering

It might seem obvious after reading some of the reasons why fluoride is in our tap water – but, by simply drinking tap water with fluoride in it we can reduce tooth decay, cavities, fillings, extractions and improve the strength of our teeth. All of this combines to reducing any oral pain or suffering we might experience throughout our lives.

Even better is that when we drink tap water throughout the day, we are getting regular bits of fluoride that can constantly help fight the battle against the bacteria in our mouths… much better than just once or twice a day (like from brushing our teeth).

Don’t forget – if you drink bottled water rather than tap water, you are probably missing out on all of the benefits of fluoride! It’s something to consider…

9. Improves quality of life – diet, mental health, sleep, school/work

I think the CDC says it all when they say:

“…oral health affects every aspect of our lives—diet, sleep, mental health, social connections, school, and work”.

centers for disease control and prevention


 “Untreated tooth decay can cause pain, school absences, difficulty concentrating, and poor appearance—all contributing to reduced quality of life and ability to succeed”.

centers for disease control and prevention

I know from first hand experience how oral health has such a big impact. Before I got my teeth fixed whenever I smiled, especially in photos, I never showed my teeth – I always hid them and hated smiling. My life changed after getting them fixed, so I totally agree with this being a reason for fluoride in our tap water!

10. Saves money

Lots of money has been saved, since water systems started adding fluoride to our tap water. Individuals and families have saved on dentist bills, and so has the health care system. According to the CDC, community water fluoridation has even been cost-saving for small and large communities.

I am sure this reason was not a surprise. We all know how expensive going to the dentist can be – yikes! Let’s face it, that is why so many people put up with toothaches, rather than heading to the dentist and getting it fixed. So perhaps that is one of the best things about fluoride in our drinking water – not just saving some money but also fewer dentists visits.

More information:

Ever wondered if fluoride being added to our tap water was supported by anyone? Well here is the ‘short list’ of major organizations that definitely support fluoridation of our water (the original list I had was more than 100 long and way too big to fit here)

  • American Dental Association
  • American Medical Association
  • US Centers for Disease and Prevention (CDC)
  • US Department of Defense
  • US Public Health Service
  • World Health Organization

In fact, fluoridation is considered so important and so beneficial that the CDC named community water fluoridation…

…one of 10 great public health achievements of the 20th century.

Centers for Disease Control and Prevention

However, it’s important to note that consuming high concentrations of fluoride is also harmful. Excessive amounts of fluoride can lead to skeletal fluorosis, where fluoride builds up in our bones. This can cause joint stiffness, pain and even fractures – especially in the elderly.

If you would like more information on how to remove fluoride from your drinking water, Water Purification Guide has detailed information available here.

The History of Fluoride in our Tap Water

As U.S. residents, we have been drinking water with added fluoride for more than 70 years!

It all began back in 1901….

1901 Frederick McKay (Dental School Graduate) notices brown stains on the teeth of Colorado Springs residents – known as “Colorado Brown Stain“.

1909 Dr Frederick McKay and dental researcher Dr Green Vardiman Black investigate the brown teeth stains – this research continues for 6 years

1915 Dr F. McKay and Dr G.V. Black determine that the brown stained teeth are also resistant to decay

1923 Dr F. McKay travels to Oakley, Idaho and discovers children with brown stained teeth, but adults with normal unstained teeth.

  • Dr F. McKay learns that the town had changed water supplies after constructing a communal water pipeline.
  • Dr F. McKay advises the town to change water supplies to a nearby spring.
  • A few years later and the children’s secondary teeth came through unstained – something was in the water that was making the teeth brown, of that Dr F. McKay was certain!

1928 Dr F. McKay and Dr Gover Kempf (United States Public Health Service) visited Bauxite, Arkansas and again discovered children with brown stained teeth – Dr F. McKay also discovered:

  • Residents in a town just 5 miles away had unstained teeth
  • Bauxite residents born before 1909 had unstained teeth, and those born after 1909 had brown stains
  • Bauxite changed its water supply in 1909 – from shallow surface wells to deep wells

1931 Dr F. McKay and Dr G. Kempf publish the results of their research into the brown stained teeth and the suggestion that it is something in the drinking water

1931 H.V Churchill, Chief Chemist at Aluminum Company of America (ALCOA) – Bauxite’s largest employer of the time, reads the research and orders the drinking water of Bauxite be tested – for everything!

1931 January 20, to be precise – H.V Churchill tells Dr F. McKay that Fluoride in Bauxite’s water is responsible for the brown staining and resistance to tooth decay, called Fluorosis

1931 Dr H. Trendley Dean, head of the Dental Hygiene Unit at the National Institute of Health, began investigating fluoride levels all around the country

1938 Dr H. Trendley Dean publishes his findings that water containing more than 1ppm fluoride (or 1mg/L) resulted in brown stained teeth, but if fluoride was in the water at a lower concentration than 1ppm – then the teeth were unstained.

1942 Dr H. Trendley Dean confirms that water with 1ppm (1mg/L) of fluoride resulted in effective teeth decay prevention and did not cause brown staining

1944 The United States Public Health Service decides on an experiment – to add fluoride to a community’s drinking water

1945 January 25, fluoride was added to the drinking water of Grand Rapids residents (Michigan) – the first time fluoride was added to water in the U.S!

Many other cities followed and added fluoride to the water supply – including:

  • Newburgh, New York (1945)
  • Sheboygan, Wisconsin (1946)
  • Marshall, Texas (1946)

1960 The Grand Rapids water fluoridation study ended after 15 years and showed that for children born after fluoride was added to the water, tooth decay was reduced by 60%!

1962 The United States Public Health Service recommended that public water supplies contain fluoride to help prevent tooth decay.

Water Purification Guide also has information on brands of bottled without fluoride available here.

States that have fluoride added to the tap water

Fluoride is added to our drinking water by the community and public water systems that treat our water. Most water systems around the country add fluoride to their water.

According to the United Health Foundation, approximately 74% of the U.S. has fluoride added to its tap water, by the community and public water systems.

States with fluoride in their water. Green states provide their fluoridation data to the CDC, grey states do not. The lowest fluoridation is in Hawaii with 12%, and the highest is in Kentucky with 99%
States with fluoride in their water. Green states provide their fluoridation data to the CDC. Data sourced from the CDC and state government websites. Image created for waterpurificationguide.com.

These 5 states have the highest rank when it comes to fluoridation – which means, these states have the greatest percentage of their populations drinking tap water with fluoride added.

  1. Kentucky – 99.9%
  2. Minnesota – 98.8%
  3. Illinois – 98.5%
  4. North Dakota – 96.7%
  5. Maryland – 96.4

But, what about the states that fare the worst when it comes to fluoridation? Here are the 5 states with the lowest fluoridation rank:

  1. Hawaii – 11.7%
  2. New Jersey – 14.6%
  3. Oregon – 22.6%
  4. Idaho – 31.9%
  5. Montana – 33.7%

Actually, the following major localities with large populations still don’t have fluoride in their water

  • Newark, New Jersey
  • Honolulu, Hawaii
  • Portland, Oregon
  • Colorado Springs, Colorado
  • Wichita, Kansas
  • Baton Rouge, Louisiana
  • Reno, Nevada

Although, it should be said that Colorado Springs has naturally, very high fluoride content in its water!

To find out how much of your state has fluoride added to its water – check out the complete list below:

State% of state
with fluoride
New Hampshire47%
New Jersey15%
New Mexico77%
New York71%
North Carolina88%
North Dakota97%
Rhode Island85%
South Carolina94%
South Dakota94%
Washington State46%
Washington DC64%
West Virginia91%

If you would like to find out if the water system that services your residence adds fluoride then you can check at the CDC’s website “My water’s fluoride”. The website allows you to search your state, county and local water system. You can navigate to their main page here.

Unfortunately, there are a few states that are not participants, which means they don’t provide the information to the CDC. These states are:

  • California
  • Hawaii
  • Maryland
  • Montana
  • New Jersey
  • New Mexico
  • Ohio
  • South Dakota
  • Washington state
  • Wyoming

If you would like a more direct method of determining if you have fluoride in your water, Water Purification Guide has a step-by-step process available here.

Related Questions

How is Fluoride added to water?

Community and public water systems add fluoride during the water treatment processes. Only approved forms of fluoride can be added – these are sodium fluoride, fluorosilicic acid and sodium fluorosilicate. For private drinking supplies, the CDC says, “it is not currently feasible to add fluoride to an individual residence’s well”.

How to remove fluoride from water?

Most water filters and water purifiers can’t actually remove fluoride from water. The only types that can successfully remove fluoride are anion exchange (activated alumina), distillation and reverse osmosis systems. More information on how to remove fluoride from tap water is available here

Theresa Orr

Theresa Orr is an Earth Scientist who specializes in determining past climates from rocks using geochemistry. Her passion for clean water drives her to breakdown the science to provide easy to understand information that everyone can read.

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