--- description: Fluoride in drinking water helps protect teeth, but it's not without controversy. Here's what to know about fluoridated water. title: The Science Behind Fluoride in Drinking Water image: https://static.time.com/v3/assets/bltea6093859af6183b/blt8ecff7c57b70fe66/6998c549e1ba00fc1c98d6ad/GettyImages-2150231449.jpg?branch=production&width=2400&quality=75&auto=webp&crop=16:9 ---  * [Health](/section/health/) ## Health Update your preferences in [Account Settings](/account/preferences/) Close * [Wellness](/tag/wellness/) ## Wellness Update your preferences in [Account Settings](/account/preferences/) Close # The Science Behind Fluoride in Drinking Water  by [Jamie Ducharme](/author/jamie-ducharme/)  ## Jamie Ducharme Update your preferences in [Account Settings](/account/preferences/) Close Ducharme is a contributor to TIME. Updated: Jan 19, 2026 3:14 PM CUTPublished: Nov 5, 2024 10:34 PM CUT  Pouring a glass of water from a kitchen faucet on Friday, April 26, 2024. Pouring a glass of water from a kitchen faucet on Friday, April 26, 2024.Leonard Ortiz—MediaNews Group/Orange County Register/Getty Images  by [Jamie Ducharme](/author/jamie-ducharme/)  ## Jamie Ducharme Update your preferences in [Account Settings](/account/preferences/) Close Ducharme is a contributor to TIME. Updated: Jan 19, 2026 3:14 PM CUTPublished: Nov 5, 2024 10:34 PM CUT Donald Trump's second term is already threatening what's lauded as one of the [top public-health triumphs of the 20th century](https://www.cdc.gov/mmwr/preview/mmwrhtml/00056796.htm "undefined"): adding fluoride, a mineral that helps prevent tooth decay, to drinking water. [That’s largely due to the influence of Robert F. Kennedy Jr.](https://apnews.com/article/rfk-kennedy-trunt-fluoride-water-eaf74072a1d037ba37475337b470dcb8 "undefined"), the U.S. Secretary of Health and Human Services, who has long advocated for the removal of fluoride from water supplies. Months before assuming his new position, Kennedy [wrote on X](https://x.com/robertkennedyjr/status/1852812012478398923?s=46 "undefined") that “the Trump White House will advise all U.S. water systems to remove fluoride from public water.” Now, [Utah](https://www.nytimes.com/2025/03/28/well/utah-fluoride-ban.html#:~:text=Utah%20has%20become%20the%20first,fluoride%20to%20public%20drinking%20water. "undefined") has become the first state to ban fluoride in public drinking water. Gov. Spencer Cox (R) signed the bill into law on March 27, and it is set to take effect on May 7\. Meanwhile, at least three other states—[North Dakota](https://ndlegis.gov/assembly/69-2025/regular/documents/25-0019-04000.pdf "undefined"), [Tennessee](https://wapp.capitol.tn.gov/apps/Billinfo/default.aspx?BillNumber=HB0897&ga=114 "undefined") and [Montana](https://bills.legmt.gov/#/laws/bill/2/LC1978?open%5Ftab=bill "undefined")—apear poised to follow suit. Adding fluoride to drinking water reduces rates of cavities by around 25%, the U.S. Centers for Disease Control and Prevention (CDC) [says](https://www.cdc.gov/fluoridation/about/index.html "undefined"). Some U.S. communities began doing so in [the 1940s](https://www.cdc.gov/fluoridation/timeline-for-community-water-fluoridation/index.html "undefined"), and today about 72% of the U.S. population that receives water from public utilities drinks fluoridated water, [according to the CDC](https://www.cdc.gov/fluoridation/php/statistics/2020-water-fluoridation-statistics.html "undefined"). Decisions about whether to use fluoride are typically made at the state or local level, and at least a dozen states require large municipalities to do so, [Stateline reports](https://stateline.org/2024/03/07/fluoride-in-public-water-has-slashed-tooth-decay-but-some-states-may-end-mandates/ "undefined"). **Read More**: [_Is Zinc Good for Colds?_](https://time.com/7160904/zinc-for-colds-supplement/ "undefined") People in countries including Australia and Canada also consume fluoride in drinking water. A 2021 [study](https://pmc.ncbi.nlm.nih.gov/articles/PMC9542152/ "undefined") demonstrated that children living in Calgary, a Canadian city that stopped fluoridating its water, developed significantly more cavities than children living in nearby Edmonton, which does use fluoride. Despite fluoride’s long-standing, federally celebrated presence in U.S. drinking water, Kennedy is not alone in opposing its use. Anti-fluoridation advocates have for decades called for the mineral to be removed from water supplies, and a number of communities, including Portland, Ore., Juneau, Alaska, and Wichita, Kans., have decided not to [add fluoride to their water](https://kffhealthnews.org/news/article/fluoride-drinking-water-local-bans/ "undefined"). Why all the controversy over a naturally occurring mineral that has been shown to [improve oral health](https://time.com/7006165/flossing-teeth-benefits/ "undefined")? Although fluoride has demonstrated benefits, namely in [reducing the risk of cavities and tooth decay](https://www.ncbi.nlm.nih.gov/books/NBK587342/ "undefined"), some studies have also raised questions about its potential link to health problems ranging from cancer to osteoporosis. The CDC [maintains](https://www.cdc.gov/fluoridation/about/statement-on-the-evidence-supporting-the-safety-and-effectiveness-of-community-water-fluoridation.html "undefined") that there is no convincing evidence linking fluoride to “any potential adverse health effect or systemic disorder,” and other major health groups, including the [American Cancer Society](https://www.cancer.org/cancer/risk-prevention/chemicals/water-fluoridation-and-cancer-risk.html "undefined") and the [American Dental Association](https://adanews.ada.org/ada-news/2024/august/national-toxicology-program-releases-fluoride-exposure-monograph "undefined") (ADA), agree that it is safe. But concerns remain—particularly about links between fluoride and cognition. In August, the U.S. National Toxicology Program (NTP) [published a report](https://ntp.niehs.nih.gov/publications/monographs/mgraph08 "undefined") that found with “moderate confidence” that—at concentrations more than twice the recommended fluoride level in the U.S.—fluoridated water is associated with modestly lower IQ scores in children. U.S. standards recommend fluoride levels of 0.7 milligrams per liter of water, and the NTP’s conclusion applied to water fluorinated at 1.5 milligrams per liter and above. Initial drafts of the report [failed to clear independent review](https://ntp.niehs.nih.gov/sites/default/files/2023-05/BSC%5FWG%5FReport%5FFinal%5FVersion%5FBSC%5Fapproved051623%5F508.pdf "undefined") by the National Academies of Science, Engineering, and Medicine, which found that the NTP’s authors hadn’t adequately supported their conclusions with data. Some pro-fluoride organizations, including the ADA, [argue](https://adanews.ada.org/ada-news/2024/august/national-toxicology-program-releases-fluoride-exposure-monograph "undefined") that the final version still falls short of providing conclusive evidence and should not lead to policy changes around water treatment. **Read More**: [_What to Expect at an Annual Physical_ ](https://time.com/7098720/annual-physical-what-to-expect-doctors-appointment/ "undefined") Tewodros Godebo, an assistant professor at the Tulane University Celia Scott Weatherhead School of Public Health and Tropical Medicine [who studies fluoride](https://pubmed.ncbi.nlm.nih.gov/37690675/ "undefined"), says studies on very high levels of fluoride exposure don’t necessarily apply to the U.S., where water typically contains much less of the mineral. Still, it’s noteworthy that even government scientists disagree about the safety of fluoridated water, says Christine Till, a professor at Canada’s York University whose research has shown a [link between fluoride and lower IQ scores in kids](https://time.com/5656476/is-fluoride-in-water-safe/ "undefined"). “One authoritative group \[the CDC\] is saying it’s safe for everyone, and another expert group from the U.S. government \[the NTP\] is saying there are concerns about adverse effects of fluoride intake on child development,” Till says. “At the very least, it’s time to acknowledge the evolving science.” A federal judge in California waded into that debate in 2024, when [he ruled](https://www.reuters.com/world/us/epa-must-address-fluoridated-waters-risk-childrens-iqs-us-judge-rules-2024-09-25/ "undefined") that the U.S. Environmental Protection Agency must strengthen regulations on fluoride to address its potential risk to children’s cognitive development. That decision does not necessarily mean fluoride must be removed from U.S. drinking water—the EPA can choose to address the situation in a number of ways, including releasing a public notice about the mineral’s potential risks and benefits—but it highlights growing scrutiny on the practice of fluoridating water, which some anti-fluoride activists argue is no longer necessary now that most people can choose to use fluoride in dental products such as toothpaste. (Till says it’s important to analyze total fluoride exposure, not just exposure through drinking water, when analyzing the mineral’s potential risks and benefits.) **Read More**: [_9 Things You Should Do for Your Brain Health Every Day, According to Neurologists_](https://time.com/7081407/brain-health-neurologist-tips/ "undefined") A [2024 Cochrane review article](https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010856.pub3/full "undefined") found that adding fluoride to drinking water may lead to slightly less tooth decay among children, but concluded that the practice’s effects are less dramatic today than they were before fluoride was widely found in toothpaste. The authors also noted that adding fluoride to drinking water may increase the number of people with [dental fluorosis](https://www.cdc.gov/oral-health/about/about-dental-fluorosis.html "undefined"), a mostly cosmetic condition that can leave the teeth with white flecks, spots, or lines. Fluoridated water, however, helps protect people that may not keep up with oral hygiene or have access to regular dental care, Godebo says—another factor that complicates any discussion about potentially adjusting the level of fluoride in U.S. water. Despite Kennedy’s suggestion that removing fluoride would be a priority in the Trump administration, Godebo says “the science is not there” to make a change to U.S. recommendations at this point. “It would be a huge decision,” he says. “It should take more years to come to a conclusion.” ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/7172655/is-fluoride-in-drinking-water-safe/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/7172655/is-fluoride-in-drinking-water-safe/"},"headline":"The Science Behind Fluoride in Drinking Water","datePublished":"2024-11-05T22:34:45.000Z","dateModified":"2026-01-19T15:14:19.000Z","description":"Fluoridated water helps protect teeth, but it's not without controversy.","url":"https://time.com/7172655/is-fluoride-in-drinking-water-safe/","keywords":["Wellness","healthscienceclimate"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/blt8ecff7c57b70fe66/6998c549e1ba00fc1c98d6ad/GettyImages-2150231449.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Jamie Ducharme","jobTitle":"Ducharme is a contributor to TIME.","url":"https://time.com/author/jamie-ducharme/"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/blt8ecff7c57b70fe66/6998c549e1ba00fc1c98d6ad/GettyImages-2150231449.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Challenge Posed By 'Forever' PFAS Chemicals In Tap Water","caption":"Challenge Posed By 'Forever' PFAS Chemicals In Tap Water","creditText":"Leonard Ortiz—MediaNews Group/Orange County Register/Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/wellness/","name":"Wellness"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/7172655/is-fluoride-in-drinking-water-safe/","name":"The Science Behind Fluoride in Drinking Water"}}]}] ```