Skip to main content Skip to site navigation

All about fluoride
Common questions and answers about fluoride from the Campaign for Dental Health


Common questions and answers about fluoride

Download this Q&A in English or Spanish - Español

Why do children need fluoride?

Fluoride is something found naturally on earth (a “mineral”) that is also in our foods and drinks. It protects our teeth, strengthens them, and keeps them from decaying. Our mouths have bacteria in them that mix with sugars in our foods and drinks to make an acid. This acid can start to eat away at our teeth and harm them by causing them to decay (causing cavities). Fluoride can repair the damage to our teeth from this acid.

We brush our teeth with fluoride toothpaste every day. Do we still need to drink tap water because it has fluoride in it? 

Yes. Drinking tap water that has fluoride in it (“fluoridated water”) is one of the best ways we can improve our whole community’s oral health. When you drink water with fluoride in it, use toothpaste with fluoride, and ask your dentist about other fluoride treatments, all of these things together are better for your oral health than doing just one of these things.

Is tap water with fluoride in it safe for me and my children to drink?

Yes. For more than 70 years, the best scientific evidence has shown that adding fluoride to community water supplies is safe and effective.

Studies show that fluoride in water is especially helpful in fighting childhood cavities.

Better community dental health helps us all save money. When more people need treatment for cavities, we all pay in the form of higher insurance premiums and taxes (

In San Mateo County, some Coastside cities served by the Coastside County Water District do not have enough fluoride in their tap water to help peoples’ oral health. In East Palo Alto, a recent report shows the majority of residents do not drink the tap water, they drink bottled water. In these areas, people should talk to their dentist to see how they can get enough fluoride to protect their teeth. There are tablets, mouthwashes, and other treatments like fluoride varnish dentists can provide. 

Are there health risks to drinking water with fluoride or using toothpaste or mouthwash with fluoride?

No. There is no trustworthy scientific evidence showing fluoridated water or dental products with fluoride in them cause illness or disease.

What is fluoride varnish?

Your dentist may recommend your child also receive fluoride treatments, like fluoride varnish to keep your child’s teeth strong and healthy. Fluoride varnish is a pale yellow substance that is painted on their teeth. It is painless. Both medical providers (like doctors or nurses) and dental providers (dentists or dental hygienists) can put fluoride varnish on your child’s teeth. It only takes a few minutes. Fluoride varnish is a free service covered by Health Plan of San Mateo Dental (HPSM Dental) for children ages 0-20. Click here for more information.