Water 101 · 10 min read
How to remove fluoride from water: what works and what doesn't
Reverse osmosis and distillation remove most of the fluoride in drinking water. Some activated-alumina and bone-char filters can remove a significant share too, but each product has to be judged on its own data.[1] Boiling doesn't remove fluoride, a water softener barely changes it, and most carbon filters don't remove it.[1][2] Before you buy anything, find out how much fluoride your water actually carries.
In many towns fluoride was added to tap water on purpose, so people who want it out of their drinking water want to know what actually takes it out. The answer depends on the method. Two technologies remove most of it, two filter media can remove a meaningful share, and the common kitchen fixes mostly don't touch it. This guide covers the hardware and leaves the fluoridation debate to the agencies we cite.
Where the fluoride in your water comes from
Fluoride reaches a tap two ways. Some utilities add it to prevent tooth decay, and some comes up naturally from the rock that groundwater moves through. EPA lists both as sources of fluoride in drinking water, along with discharge from fertilizer and aluminum factories.[3]
A few numbers frame the conversation. Where water is fluoridated, the U.S. Public Health Service recommends 0.7 mg/L, a level CDC notes is not an enforceable standard, and states and local governments decide whether to fluoridate at all.[4] EPA's enforceable limit is 4.0 mg/L.[3] In April 2025, EPA announced it would review new science on fluoride and prepare an updated health effects assessment, citing a National Toxicology Program conclusion, reached with moderate confidence, that exposure above 1.5 mg/L is associated with lower IQ in children.[5]
In Utah the question changed in 2025. House Bill 81 prohibits adding fluoride to public water systems, effective May 7, 2025.[6] Natural fluoride didn't go anywhere. Salt Lake City's 2026 water quality report says the city stopped adding it and now measures naturally occurring fluoride between 0.0 and 0.28 mg/L, with a system-wide average of 0.115 mg/L, against the old fluoridation target of 0.7 mg/L.[7] Our walk through what's really in Salt Lake City's tap water covers the rest of that report.
Private wells are their own story. Nobody adds fluoride to a well, but the natural level depends on the geology under the property, which is why the American Dental Association suggests testing a private well every year for fluoride.[1]
Measure your fluoride before you buy anything
A filter decision starts with a number. On city water, your utility publishes an annual Consumer Confidence Report with its test results.[8] On a well, a lab test is the only way to know. Our guide to what's actually in your tap water shows where to find each one.
Read the units carefully. Labs report fluoride in mg/L, which is the same as parts per million. A good lab report also lists a detection limit for each result. "Not detected" means the lab couldn't measure fluoride above that limit. It doesn't mean zero.
Then decide what you're aiming for. Taking fluoridated water at 0.7 mg/L down to near zero is a different job from bringing a high-fluoride well under the 4.0 mg/L federal limit. A membrane removes a share of what comes in, so more in means more left over.[8]
Methods that reduce fluoride
| Method | What it does with fluoride | What it costs you |
|---|---|---|
| Reverse osmosis | Removes most of it when working properly [1] | Removes calcium and magnesium too; a typical unit sends five gallons or more to the drain per gallon made [9][10] |
| Distillation | Removes most of it [1][12] | Electricity, a few gallons a day, and a boiling chamber that has to be descaled [12] |
| Activated alumina filters | Some can remove a significant amount [1] | Varies by product; judge each one on its own data [1] |
| Bone char filters | Some can remove a significant amount [1] | Varies by product; judge each one on its own data [1] |
Reverse osmosis pushes water through a semipermeable membrane under household pressure. Water passes through to a storage tank. Most of what's dissolved in it, fluoride included, stays on the other side and gets flushed to the drain. A University of Nebraska–Lincoln Extension guide lists fluoride among the contaminants household RO units remove.[8] We go deeper on how much, and what it costs, in does reverse osmosis remove fluoride?
Distillation boils water and collects the steam. Fluoride, nitrate, sodium and the hardness minerals don't travel with the steam, so they collect in the boiling chamber with the other dissolved solids.[12] We compare the two machines side by side in distilled vs. reverse osmosis.
Activated alumina and bone char are filter media. The American Dental Association's guidance is careful: some filters with these media can remove significant amounts of fluoride, and each type of filter should be assessed on its own.[1] Like any filter media, they work until they're spent, so check the rated capacity for fluoride.
What doesn't remove fluoride
Boiling. Heating or boiling water does not remove fluoride.[2] The water that boils off leaves the fluoride behind, so a long boil leaves the same fluoride in less water.
A water softener. The softening process does not significantly change fluoride levels.[1]
Most carbon filters. Many pitcher, faucet-mount and fridge filters are built around carbon, and the ADA's summary is blunt: most carbon filters do not remove fluoride.[1] If a carbon product claims fluoride reduction, it should be able to show fluoride on its own test data.
What each method costs you
Reverse osmosis takes the minerals along with the fluoride. The World Health Organization's review of nutrients in drinking water notes that desalination by reverse osmosis "depletes the source water of its mineral contents."[9] It also uses water. EPA WaterSense says a typical point-of-use system generates "five gallons or more of reject water for every gallon of treated water produced," while WaterSense-labeled units have to send 2.3 gallons or less down the drain.[10] Add a storage tank that usually holds 2 to 5 gallons, a separate faucet, pre-filters, post-filters and a membrane to look after.[8] If you miss the minerals, there's a fix with its own upkeep, laid out in reverse osmosis with remineralization.
Distillation is slow and runs on electricity. The University of Nebraska–Lincoln Extension guide puts batch distillers at 3 to 10 gallons a day, names electricity as the biggest operating cost, and works an example of about 33 cents a gallon for an 1,100-watt unit at the $0.10 per kilowatt-hour rate it used in 2013.[12] Plug in your own electric rate before you compare. The boiling chamber collects scale that has to be cleaned out, and people often describe distilled water as flat.[12]
With activated alumina and bone char, the open question is the product itself. Performance rides on the specific filter and on changing the media before it's spent, so ask for fluoride data, not a media name.
How to check a fluoride claim before you pay
The Nebraska RO guide notes that federal, state and local laws don't regulate home reverse osmosis units. The industry regulates itself, with NSF and the Water Quality Association certifying products.[8] That puts the checking on you, and it's quick.
- Find fluoride by name on the performance data sheet, with the level it was tested at and the result.
- If the product claims a certification, look it up in the certifier's own listing and confirm fluoride is on it. Under NSF/ANSI 58, total dissolved solids reduction is the required claim for reverse osmosis and fluoride reduction is optional, so a certified RO unit isn't automatically certified for fluoride.[11]
- Check the rated capacity and the replacement schedule. A filter reduces fluoride only until its media is spent.
- Test before and after. A lab result for your own tap and your own filtered water is the most direct proof you can get.
Minnesota's health department puts the bigger rule plainly: no single treatment unit handles every contaminant, and certifying organizations don't certify units for every contaminant.[13] Our guide on how to read a water filter spec sheet walks through the reduction table line by line.
Where our system fits, and the evidence we can show
We sell a catalytic-carbon system, not reverse osmosis, so weigh this section with that in mind. Given what the ADA says about carbon filters, you should be skeptical of any carbon-based fluoride claim, ours included. So this is the evidence we have, and its limits.
Sentry H2O, the manufacturer of the systems we carry, published a SimpleLab report on Tempe, Arizona city water sampled on May 5, 2025. The untreated hose-bib sample measured 0.52 mg/L fluoride. The "Treated Sink" sample showed no fluoride above the lab's 0.004 mg/L detection limit, which means fluoride dropped by at least 99.2% in that one sample.[14]
The minerals went the other way in the same pair of samples: calcium read 55.27 mg/L before and 56.45 mg/L after, magnesium 18.22 mg/L before and 26.63 mg/L after, and pH moved from 6.83 to 8.21.[14]
Read those numbers with the limits attached. Sentry H2O collected the samples, and the full report and our method notes are on the Science page.
About these samples (provisional): Sentry H2O's draft, not-yet-final answers describe the 2025 "Treated Sink" sample as a TriGuard under-sink system at the 500-gallon mark and the "Kitchen Sink" sample as a whole-house system at about 100,000 gallons (roughly one year for a family of three). Sentry has not yet supplied the per-report sample crosswalk, so we do not attribute these results to any current SKU. Results are specific to the sampled water and configuration and are not a certification or a guarantee of identical performance in every water source.
If fluoride is the main reason you're shopping, I'd test your own water before and after, whatever you end up buying. The Sentry H2O Wellness System is the under-sink system on our kitchen filtration page, and our Sentry H2O vs. reverse osmosis comparison shows where RO comes out ahead, too.
Free one-page checklist
Is your filter doing what you think?
A printable page: what each filter type is documented to reduce, five questions to ask a seller, and where to confirm a certification yourself. No email needed.
Frequently asked questions
Does boiling water remove fluoride?
No. A health consultation by Idaho health officials and the federal Agency for Toxic Substances and Disease Registry states that heating or boiling water does not remove fluoride. As water boils off, the fluoride stays in the pot.
Do pitcher filters remove fluoride?
Usually not. The American Dental Association says most carbon filters do not remove fluoride. A pitcher that claims fluoride reduction should list fluoride by name on its own test data or certification listing.
Does a water softener remove fluoride?
No. The American Dental Association notes that the water-softening process does not significantly change fluoride levels.
Is fluoride still added to Salt Lake City water?
No. Utah law has prohibited adding fluoride to public water systems since May 7, 2025. Salt Lake City's 2026 water quality report says natural fluoride now measures between 0.0 and 0.28 mg/L, with a system-wide average of 0.115 mg/L.
Does bottled water contain fluoride?
It depends on the water. CDC says bottled water labeled de-ionized, purified, demineralized or distilled contains no or only trace amounts of fluoride. Other bottled waters vary, so check the label or ask the bottler.
Which method removes the most fluoride?
Reverse osmosis and distillation both remove most of the fluoride when the equipment is working properly, according to the American Dental Association. The figure for a specific unit is on its performance data or certification listing, so compare documents rather than marketing.
Sources
[1] American Dental Association, Fluoridation Facts (2025), Question 16, p. 35: home water treatment systems and fluoride.
[2] Idaho Division of Public Health and the Agency for Toxic Substances and Disease Registry, Health Consultation: Sweet Area Fluoride (September 9, 2009): boiling, reverse osmosis and distillation.
[3] U.S. EPA, National Primary Drinking Water Regulations: fluoride limit and sources.
[4] CDC, Community Water Fluoridation Frequently Asked Questions: recommended level and bottled water.
[5] U.S. EPA news release, EPA Will Expeditiously Review New Science on Fluoride in Drinking Water (April 7, 2025).
[6] Utah Legislature, H.B. 81 Fluoride Amendments (2025 General Session), enrolled copy.
[7] Salt Lake City Department of Public Utilities, 2026 Water Quality Report (PDF): fluoride section.
[8] Bruce I. Dvorak and Sharon O. Skipton, Drinking Water Treatment: Reverse Osmosis, NebGuide G1490, University of Nebraska–Lincoln Extension (revised 2014).
[9] World Health Organization, Nutrients in Drinking Water (Geneva: WHO Press, 2005), p. 76: desalination and mineral depletion.
[10] U.S. EPA WaterSense, Point-of-Use Reverse Osmosis Systems: reject-water figures.
[11] NSF, NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems: required and optional claims.
[12] Bruce I. Dvorak and Sharon O. Skipton, Drinking Water Treatment: Distillation, NebGuide G1493, University of Nebraska–Lincoln Extension (revised 2013).
[13] Minnesota Department of Health, Home Water Treatment Facts.
[14] SimpleLab, Tempe, Arizona toxins and minerals report, samples collected May 5, 2025, privacy-redacted copy (PDF). Sample attribution is provisional; see the Science page method notes.
Keep reading
Educational guidance only, not medical or dental advice. This article describes water-treatment methods and cites published guidance from U.S. and state agencies, the World Health Organization, the American Dental Association and university extension services. It takes no position on community water fluoridation; ask your dentist or doctor about fluoride and your family's health. No water filtration system prevents, treats, or cures any disease.