Is Fluoride in Water Bad for You?

Fluoride is a mineral found in many natural water sources all over the world. And it’s key for healthy teeth and bones. For more than 70 years, it has been added to drinking water in the U.S. This move has been hailed as one of the greatest public health achievements of the 20th century. 

However, not everyone agrees. Some advocacy groups claim that fluoride is harmful. Recently, Utah went as far as to ban fluoride from drinking water. And other communities may follow their lead.

But is fluoride in water bad for you? Here’s what the experts and research say.

Is fluoride in water bad for you?

Ingesting fluoride isn’t necessarily harmful. In fact, adults need roughly 3 mg of fluoride daily to prevent tooth decay and maintain strong bones. 

Fluoride works by strengthening the surface of the tooth (enamel). This helps protect the teeth from acid — which forms when bacteria in your mouth break down sugar and starch in the foods you eat. It’s this acid that wears down the teeth, causing tooth decay. 

By supplying your teeth with a steady supply of fluoride, you can help safeguard them from harmful acid. You can even repair early acid damage before things get worse. 

So, fluoride in water is generally beneficial. “It’s the amount of fluoride in water that determines whether it’s bad for you,” said Megan Meyer, PhD, a science communications consultant based in Durham, North Carolina. 

Fluoride can be bad for you when levels reach 1.5 mg per liter (mg/L) of water. We go through the potential health risks of fluoride in more detail below. 

“The recommended fluoride concentration in drinking water is 0.7 mg/L,” Meyer said. That’s equal to roughly 3 drops of water in a 55 gallon barrel, according to the CDC.

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Why is fluoride added to water?

The fluoride in tap water serves the same purpose as the fluoride in your toothpaste: to help prevent cavities and promote oral health. Research suggests that fluoridated water decreases tooth decay, especially in children.

Most public tap water contains naturally occurring fluoride. However, the levels are often too low to benefit your teeth. For this reason, many state and local governments choose to add extra fluoride to the water supply. Community members often have a say in whether to adjust the fluoride level.

In some communities, the water naturally contains fluoride at a level proven to prevent cavities, Meyer said. So, not every city needs to (or does) supplement their drinking water with fluoride.

Either way, fluoridated water accounts for most of the fluoride you consume daily. The remainder comes from foods and beverages made with fluoridated water, as well as toothpaste and mouthwash.

What are the risks of drinking water with fluoride?

Fluoridated water is an effective and inexpensive way to promote oral health. It’s also supported by decades of research. 

“That said, like many nutrients or additives, more isn’t always better,” said Eboni Cornish, MD, the functional medicine director at Amen Clinics’ East Coast Division. 

Health risks can emerge when fluoride levels get too high. The potential risks include:

• Tooth discoloration: The most common side effect of getting too much fluoride is dental fluorosis, Dr. Cornish said. This is a cosmetic condition that only occurs in children while their teeth are still growing. Exposing young teeth to too much fluoride creates white lines or streaks on the teeth. Thankfully, dental fluorosis doesn’t impact the health of teeth. It’s also mild in most cases. 

• A lower IQ: One review found that drinking water with higher fluoride levels (above 1.5 mg/L) is associated with lower IQ in children.

• Bone fractures: Research shows that the risk of bone fracture increases once fluoride levels reach 1.5 mg/L. 

While rare, drinking water with high amounts of fluoride for many years can cause a bone disease called skeletal fluorosis. It causes digestive symptoms like constipation and abdominal pain during the early stages. Over time, it can lead to joint pain or stiffness and osteoporosis. 

“It’s important to note that these risks are associated with excessive fluoride intake — not the controlled levels used in community water systems,” Meyer noted. 

How are fluoride levels in water measured?

If you get your water from a public water system, the utilities that provide your water measure and maintain fluoride levels regularly. They spell out their findings in a water quality report sent to residents at least once a year. This way, you can see how much fluoride is in your water. 

The U.S. Environmental Protection Agency (EPA) also reviews these reports to ensure your community meets federal standards. 

Why trust our experts?

Written by:

Lauren Bedosky

Lauren Bedosky has been a freelance health and fitness writer for nearly a decade. She has written for many brands and publications, including Runner's World, Nike, the UFC, Women's Health, and BlueCross BlueShield.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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