Yes, most tap water in the United States contains fluoride. As of 2022, 72.3% of Americans served by community water systems, more than 209 million people, receive fluoridated water. The fluoride is added intentionally to help prevent tooth decay, though some water sources also contain naturally occurring fluoride from mineral deposits underground.
How Fluoride Gets Into Tap Water
Fluoride enters tap water through two routes: it occurs naturally in groundwater as it passes through rocks and soil, or it’s deliberately added at water treatment plants. Groundwater in the western U.S. tends to have higher natural fluoride concentrations than in the eastern part of the country, according to the U.S. Geological Survey. In areas where natural levels are low, water utilities add fluoride to bring concentrations up to a target level.
Community water fluoridation started in 1945, when Grand Rapids, Michigan became the first city in the world to add fluoride to its drinking water. The practice spread rapidly after researchers found dramatic drops in childhood cavities. Today the U.S. Department of Health and Human Services recommends a fluoride concentration of 0.7 milligrams per liter (mg/L), which is roughly equivalent to 0.7 parts per million. That number was lowered from a previous range of 0.7 to 1.2 mg/L to account for the fact that people now get fluoride from other sources too, like toothpaste and certain foods.
What Fluoride Does for Teeth
Fluoride strengthens tooth enamel and makes it more resistant to the acid that mouth bacteria produce after you eat. Between 1945 and 1999, community water fluoridation reduced cavities in children by 40 to 70 percent and tooth loss in adults by 40 to 60 percent. Children born after fluoride was added to their community’s water had cavity rates more than 60 percent lower than older peers who grew up without it.
The effects of removing fluoride are equally telling. When Juneau, Alaska stopped fluoridating its water in 2007, cavity-related dental procedures in children and adolescents increased by nearly 50 percent.
Potential Concerns at Higher Levels
The most common side effect of fluoride exposure is dental fluorosis, a cosmetic change in the appearance of tooth enamel that happens when children consume too much fluoride while their teeth are still developing (typically under age 8). About 23 percent of Americans aged 6 to 49 show some degree of fluorosis, but the vast majority of cases are very mild or mild, appearing as small white specks or faint white streaks on the teeth that most people wouldn’t notice without a dental exam.
The breakdown: 16 percent of people had very mild fluorosis (small white spots covering less than 25 percent of the tooth surface), about 5 percent had mild fluorosis, 2 percent had moderate fluorosis, and less than 1 percent had severe fluorosis involving pitting of the enamel. Severe fluorosis is rare at the fluoride levels found in U.S. drinking water.
The EPA set a maximum contaminant level for fluoride at 4.0 mg/L, nearly six times the recommended treatment level. That limit, established in 1986 and most recently reviewed in 2024, is designed to prevent more serious health effects from long-term exposure to high fluoride concentrations.
How to Check Your Local Water
Not all community water systems add fluoride, and levels vary by location. The simplest way to find out what’s in your tap water is your utility’s annual Consumer Confidence Report, which every water system is required to send to its customers. It lists fluoride levels along with other water quality data. You can also use the CDC’s “My Water’s Fluoride” online tool, which lets you look up whether your local water system shares fluoride data with the CDC. If you’re on a private well, your water won’t be fluoridated (no one is adding it), though it may contain natural fluoride depending on your local geology. A water test from a certified lab will give you an exact number.
Which Filters Remove Fluoride
If you want to reduce fluoride in your tap water, the type of filter matters significantly. Standard carbon pitcher filters (like most Brita or PUR models) and charcoal filters do not remove fluoride. Water softeners also leave fluoride levels essentially unchanged.
Filters that do remove significant amounts of fluoride include:
- Reverse osmosis systems: These push water through a semi-permeable membrane and are one of the most effective options for fluoride removal.
- Water distillation units: These boil water and collect the steam, leaving fluoride behind.
- Activated carbon filters with activated alumina: A specialized version of carbon filtration that can remove meaningful amounts of fluoride, though effectiveness varies by product.
If you’d prefer to keep fluoride in your water (for the dental benefits), look for the American Dental Association’s Seal of Acceptance on water filter packaging. The ADA places that seal on effective filters that do not remove fluoride, making it easy to filter out other contaminants while preserving the fluoride content.