Fluoride

1.5 mg/Lof fluoride is the level US government scientists linked to lower IQ in children. It’s also the most Australia allows in your tap water, and that limit was set to protect teeth, not brains.

Source: US National Toxicology Program (2024)

Harrison Spanner · 24 Oct 2026 · 6 min read

Aerial view of the Wagga Wagga water treatment plant, with round settling tanks and buildings beside a river lined with gum trees — The water treatment plant at Wagga Wagga, NSW. Riverina Water is approved to add fluoride at its Wagga plants. Photo: Bidgee, CC BY-SA 3.0 AU, via Wikimedia Commons

About 89% of Australians have fluoridated water on tap. You didn’t choose it, and neither did your kids. In 2024 the US government’s own toxicology program concluded that fluoride above 1.5 mg/L is linked to lower IQ in children, and said it didn’t have the data to tell whether the lower level used in the US is safe. Australia’s limit is 1.5 mg/L. The gap between what’s in your tap and what’s linked to harm is thinner than you’ve been told.

89%of Australians have access to fluoridated drinking water

74studies pooled in a 2025 review that linked more fluoride to lower child IQ

4.49fewer IQ points in boys per 1 mg/L of fluoride in their mother’s urine in pregnancy, in Canada

How it works

From the treatment plant to your child

Four steps. The last is the open question.

Based on the NHMRC, the US CDC and the National Toxicology Program

Step 3 isn’t a claim from campaigners. The US CDC says powdered formula mixed with fluoridated water “may increase the chance of dental fluorosis”, the white marks on teeth, and suggests parents use low-fluoride bottled water some of the time.

The evidence, from the US government’s own scientists

The National Toxicology Program found a link. In 2024 it concluded with moderate confidence that water above 1.5 mg/L is associated with lower IQ in children. For the 0.7 mg/L used in the US, it said there were “insufficient data” to tell.
74 studies point the same way. A 2025 meta-analysis found each 1 mg/L more fluoride in children’s urine meant 1.63 fewer IQ points. Most studies came from China and India, and 52 were rated high risk of bias. Across all water studies the link faded below 1.5 mg/L, but in the better-quality studies it held even there.
Canadian mothers, at normal levels. In cities under Canada’s 1.5 mg/L limit, each 1 mg/L more fluoride in a pregnant mother’s urine meant 4.49 fewer IQ points in her son, across 512 mother and child pairs. There was no significant link in girls.
A US federal judge called it a risk. In 2024 Judge Edward Chen ruled that 0.7 mg/L “poses an unreasonable risk of reduced IQ in children”. An appeals court overturned it in May 2026 on procedure, without ruling on the science.

A green historical marker titled The Beginning of Water Fluoridation outside a red brick water filtration plant — The marker in Grand Rapids, Michigan, which in January 1945 became the first city to add fluoride to its water. Photo: Staircase1, CC BY-SA 4.0, via Wikimedia Commons

Australia’s fluoride limit was set to stop marks on children’s teeth. Brain development wasn’t the basis for it.

Australia’s limit sits right on the line

The Australian Drinking Water Guidelines say fluoride should not exceed 1.5 mg/L. That number, in a fact sheet endorsed in 1996, was set to protect children from dental fluorosis. It’s the same level the US toxicologists linked to lower IQ. Fluoridated towns aim lower, at 0.6 to 1.1 mg/L, but the US scientists said there wasn’t enough data to clear even 0.7 mg/L.

Fluoride levels in drinking water

Milligrams per litre

Typical unfluoridated supply<0.1

US recommended level0.7

Top of Australia’s range1.1

Australian limit = US IQ line1.5

The top of Australia’s range is 73% of the level linked to lower IQ.

Sources: Australian Drinking Water Guidelines; NTP (2024)

The official reassurance hasn’t moved. The NHMRC’s position that fluoridation is safe, effective and ethical dates from 2017, years before the NTP review and the 74-study analysis. To be fair, there is evidence on its side. An Australian study of 357 young adults found no lower IQ in those who grew up on fluoridated water, and a 2026 study of 10,317 people in Wisconsin found no difference either. But both estimated exposure from where people lived, and neither measured fluoride in urine, as the Canadian and pooled studies did.

A hand holding a clear glass of water — You can’t opt out of the town supply. You can choose what goes in the glass. Photo: engin akyurt, Unsplash Licence, via Unsplash

The fix: filter what you drink and mix

You can’t vote fluoride out of your town’s water this week. You can take it out of the water your family drinks. Ordinary jug and carbon filters don’t do it; Alberta’s health service names reverse osmosis and distillation as the methods that work. If you buy a filter, pick one whose maker tests it for fluoride. If you’re pregnant or mixing formula, that’s where it matters most.

What each fix does

Take fluoride out where it’s swallowed.

Sources: Waters Co BioMax; Waters Co MyWaterJug; US CDC

Waters BioMax under-sink fluoride filter

In the shop

Waters BioMax Under-Sink Filter

The set-and-forget option: it sits under the sink and feeds its own tap, so every glass and pot of water is filtered. Waters Co says it reduces up to 99.9% of fluoride, plus PFAS and lead, and one filter set lasts 1.5 to 3 years. DIY or handyman install, tap sold separately. A$999.

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MyWaterJug 1.5L fluoride filter jug with 3 replacement filters

In the shop

MyWaterJug + 3 Replacement Filters

The budget option, from Australian filter maker Waters Co. Most jug filters don’t touch fluoride, which is why Alberta’s health service warns against them. Waters Co says independent laboratory testing shows its filters remove up to 99% of fluoride. That’s the maker’s claim, so ask for the lab report if you want to see it. No plumbing, no power, and 4 cartridges is about a year of water. A$189.

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In the shop

Waterman Portable Filter

For the gym, car or office. It takes the same cartridge as the MyWaterJug, so you get the same filtering away from home. Fill from any tap. A$89.95.

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Do this today

1. Find out what’s in your tap. Ask your water supplier whether your town is fluoridated and at what level.
2. Filter your drinking and cooking water. An under-sink fluoride filter or reverse osmosis if you can, a fluoride-tested jug if you can’t.
3. If you’re pregnant or mixing formula, use filtered water, or bottled water labelled purified, demineralised or distilled, as the CDC itself suggests.

Fluoride isn’t the only chemical in your kitchen. Read what’s on non-organic food.

Go deeper

The Case Against Fluoride by Paul Connett, James Beck and H. Spedding Micklem. The scientific case against fluoridation.
The Fluoride Wars by R. Allan Freeze and Jay H. Lehr. A history of America’s long political fight over fluoridation.

What to make of it

Australia’s fluoride limit was set to protect children’s teeth, not their brains. The US government’s own scientists now link the same level to lower IQ, and can’t say the lower levels are safe. The official position here was written before any of that. You don’t need to wait for it to catch up. Filter what your family drinks, starting with the baby’s bottle.

Sources

Products marked “In the shop” link to partner stores, and I may earn a commission if you buy, at no extra cost to you. Amazon links are affiliate links. As an Amazon Associate I earn from qualifying purchases.

This article is general information only and isn’t medical or dental advice. Water filters are household products, not medicines. Speak to your doctor, dentist or pharmacist about your own or your children’s health before changing anything.