Fluoride in Toronto's Water: What Parents Need to Know
Clinically reviewed by Dr. Abinaash Kaur, DDS, RCDSO, on 2026-07-23. Dr. Kaur is a general dentist in Toronto (Bloor West Village) registered with the Royal College of Dental Surgeons of Ontario.
Toronto's tap water carries less than half the fluoride concentration used in the research that set off the panic on your feed. At the level our city adds, Health Canada, the Public Health Agency of Canada and the Canadian Dental Association all say fluoridated water is safe for children to drink.
I've been treating families in Bloor West Village for about 25 years, and this question has gone from rare to weekly. A parent waits until the hygienist steps out, then asks quietly whether they should be filtering the tap. Nobody wants to be the one who poisoned their kid. Nobody wants to be the one who caused six cavities either.
So here are the numbers, the study everyone is sharing, and what I'd do if you're still uneasy. No lecture in this one.
How much fluoride is in Toronto's tap water?
Less than you'd guess from the internet.
Toronto Water tests for it constantly. Across 1,589 samples taken through 2024, fluoride in the city's drinking water averaged 0.66 mg/L, with a maximum reading of 0.81 mg/L (City of Toronto Drinking Water Analysis Summary 2024).
Two reference points make that number mean something.
Health Canada sets the optimal level of fluoride in Canadian drinking water at 0.7 milligrams per litre, which you'll also see written as 0.7 parts per million. Optimal here means the concentration that delivers the dental benefit while minimizing the risk of dental fluorosis, and it already accounts for the fluoride people get from toothpaste and mouth rinse (Health Canada).
The maximum acceptable concentration, meaning the safety ceiling, is 1.5 mg/L (Health Canada).
So our tap sits a hair under the target and well under half the ceiling. That's the entire picture on dose, and everything below hangs off it.
What did that IQ study find?
Here's where most people think the science flipped. The paper and the headline don't say the same thing.
In March 2025, JAMA Pediatrics published a systematic review and meta-analysis of 74 studies on fluoride exposure and children's IQ scores (JAMA Pediatrics). It found inverse associations between fluoride exposure and IQ across that literature, along with a dose-response pattern. That part is real and I'm not going to wave it away.
Now the details that didn't fit in a caption.
Of the 74 studies, 45 were done in China, 64 were cross-sectional, and 52 were rated high risk of bias (JAMA Pediatrics).
This is the line that matters for a Toronto parent. In the 31 studies that measured fluoride in drinking water, the inverse association held when exposed groups were restricted to under 4 mg/L and under 2 mg/L, and the association was null at under 1.5 mg/L (JAMA Pediatrics).
Null, in the range that contains our water.
You deserve the caveat too, because the authors printed it themselves. Restricted to the low risk-of-bias studies, the association stayed inverse below 1.5 mg/L, and their own conclusion says there were limited data and uncertainty in the dose-response relationship below 1.5 mg/L when exposure was estimated from drinking water alone (JAMA Pediatrics). Their urine analyses found an IQ decrease of 1.63 points per 1 mg/L rise in urinary fluoride (JAMA Pediatrics).
A fair reading goes like this. At high exposures, mostly measured far from Canada, the signal is consistent. At the level in a Toronto glass, the drinking-water estimates showed nothing, and the evidence down there is thinner than anyone would like. That's a real gap in the science, not a cover-up, and you're allowed to hold both thoughts.
The Public Health Agency of Canada's position is that there's no scientific evidence to suggest children should avoid drinking fluoridated water at the accepted levels in Canadian drinking water (Public Health Agency of Canada).
What happened when a Canadian city took it out?
Did you know about this? We didn't have to guess. Calgary ran the experiment for us.
Start with what fluoridation is supposed to buy. Community water fluoridation is associated with roughly a 25% reduction in tooth decay in children and adults, and in 2022 about 73.2% of Ontario's population had it, compared with 38.8% across Canada (Public Health Agency of Canada).
Calgary began fluoridating in 1991. City Council directed staff to stop in 2011, and the water stayed unfluoridated for more than a decade (City of Calgary).
Researchers then tracked Grade 2 children in Calgary against Grade 2 children in Edmonton, which never stopped. Decay in baby teeth rose in both cities between 2004/2005 and 2013/2014, and the size of that increase was greater in Calgary, where fluoridation had ceased (Community Dentistry and Oral Epidemiology).
A second study followed it out seven years past cessation, sampling 2,649 Calgary children and 2,600 Edmonton children in 2018/2019. Social gaps in dental health were present in both cities, and they tended to be worse in Calgary (Canadian Journal of Public Health). Kids with no dental insurance carried more untreated decay, and in Calgary that gap widened after cessation (Canadian Journal of Public Health).
Calgarians noticed. In the 2021 municipal election 62% of voters backed bringing fluoride back, Council directed the change that November, and fluoride returned to Calgary's drinking water on June 30, 2025 (City of Calgary).
A city took it out, watched what happened to its children's teeth, and voted it back in. That's not a talking point. That's a decade of Grade 2 dental exams.
Is my child already getting too much?
Good question, and the answer comes with an age limit attached.
Dental fluorosis is a change in how tooth enamel looks: small white lines or flecks on the adult teeth. It happens only if a young child swallowed too much fluoride while the permanent teeth were still forming under the gums, and you can't develop it once the adult teeth have grown in (Health Canada).
The Canadian Health Measures Survey found 16% of children had very mild or mild dental fluorosis, made up of 12.0% very mild and 4.4% mild (Health Canada). Moderate or severe fluorosis turned up in fewer than 0.3% of children, too few to report (Health Canada).
In its mild form it's a cosmetic outcome and doesn't affect oral health or overall health (Health Canada).
Here's a thing I see in the chair that no article warns parents about. Most of the white marks that scare a parent in our west-end practice aren't fluorosis at all. They're chalky patches of early decay sitting along the gumline under plaque, and those are the ones I want to find early. Our post on whether a cavity can heal itself explains which white spots can still be turned around and which ones can't.
How much toothpaste should my kid use?
Try this: control the toothpaste, not the tap. That's where a child's fluoride dose is genuinely in your hands.
- Under 3 years old, talk to a health professional about your child's decay risk. Children at risk should have their teeth brushed by an adult using a minimal, rice-grain-sized amount of fluoridated toothpaste (Health Canada). If the child isn't at risk, the Canadian Dental Association says an adult should brush with a toothbrush moistened with water only (Canadian Dental Association).
- Ages 3 to 6, an adult should always help, using only a small green-pea-sized amount, 5 mm maximum (Health Canada).
- Age 6 and up, once your child can spit the toothpaste out, they're ready for supervised brushing with fluoride toothpaste (Health Canada).
Toothpaste is a concentrated product, which is the whole reason the age rules exist (Health Canada). A toddler who eats toothpaste off the brush every night is a bigger fluoride question than a toddler who drinks tap water. Our guide to your baby's first tooth and first visit covers when to start and what that first appointment looks like.
Can I use tap water in baby formula?
Yes, and this one has a plain federal answer.
Municipal tap water and commercially bottled water, apart from carbonated or mineral waters, are safe for preparing powdered or concentrated infant formulas (Health Canada). Adding fluoridated tap water to powdered or concentrated liquid formula is safe (Health Canada).
The exception is narrow and specific. If you live somewhere with natural fluoride levels higher than the 1.5 mg/L guideline, Health Canada suggests mixing formula with water of lower fluoride concentration (Health Canada). Toronto isn't that place. A private well is a different conversation, since groundwater fluoride varies and testing it falls to the owner (Health Canada).
If you'd still rather lower fluoride intake during infancy, Health Canada lists the ways: breastfeed, since breast milk contains 5 to 10 micrograms of fluoride per litre; mix formula with fluoride-free or low-fluoride water such as purified, deionized, demineralized or distilled; or use ready-to-feed formula (Health Canada).
Notice what isn't on that list. Nobody suggests you stop your child drinking water. Our baby oral health guide picks up the rest of the first year.
What if I still don't want fluoride?
Have no fear, you won't get a speech from me.
Families all over Baby Point and the Junction filter their water, buy hydroxyapatite toothpaste, or drink bottled. I'd far rather you tell me than hide it, because it changes what I do at your child's appointment, not what I think of you. Some days the schedule pushes me hard, and this is still a conversation I'll make time for.
Here's what I'd want in place instead:
- Fluoride varnish at recall visits. Health Canada lists varnish as a way to prevent tooth decay in people at risk, painted on by someone trained to do it (Health Canada), and the Canadian Dental Association supports professional application of fluoride varnish for people at risk (Canadian Dental Association).
- Brushing twice a day with fluoridated toothpaste in the age-appropriate amount (Canadian Dental Association).
- A shorter recall interval so a white spot gets caught before it turns into a filling. Our post on how often you need a dental cleaning explains how we pick that number per patient.
- Sugar frequency over sugar total. Constant sipping does more damage than one dessert.
The Canadian Dental Association's own position, after more than 50 years of research, is that fluoride is safe and effective at preventing tooth decay, and it supports fluoridation of municipal drinking water as a safe, effective and economical way to prevent decay in all age groups (Canadian Dental Association). That's where I stand too. Your kid's teeth still get looked after either way.
Frequently Asked Questions
Q: Is Toronto's tap water safe for my kids to drink? Yes. Toronto's drinking water averaged 0.66 mg/L of fluoride across 1,589 samples in 2024 (City of Toronto), which sits just below Health Canada's optimal level of 0.7 mg/L and well under the 1.5 mg/L maximum acceptable concentration (Health Canada). The Public Health Agency of Canada states there's no scientific evidence that children should avoid drinking fluoridated water at the levels accepted in Canadian drinking water (Public Health Agency of Canada).
Q: Does the 2025 IQ study mean I should stop giving my child tap water? No, and the paper is more careful than the headlines. The JAMA Pediatrics meta-analysis of 74 studies found the drinking-water association was null below 1.5 mg/L, though the authors noted limited data and uncertainty in that range when exposure was estimated from drinking water alone (JAMA Pediatrics). Of those 74 studies, 45 were conducted in China and 52 were rated high risk of bias (JAMA Pediatrics). Toronto's water is far below the exposures that drove the finding.
Q: How much toothpaste should a 2-year-old use? Ask a health professional whether your child is at risk of tooth decay first. If your child is at risk, an adult should brush using a minimal, rice-grain-sized amount of fluoridated toothpaste (Health Canada). If your child isn't at risk, the Canadian Dental Association says to brush with a toothbrush moistened with water only (Canadian Dental Association). From ages 3 to 6, an adult helps and the amount moves up to a small green pea, 5 mm maximum (Health Canada).
Q: Can I make baby formula with Toronto tap water? Yes. Municipal tap water is safe for preparing powdered or concentrated infant formula, and adding fluoridated tap water to those formulas is safe (Health Canada). The exception applies to areas where natural fluoride levels run above the 1.5 mg/L guideline, where Health Canada suggests mixing with lower-fluoride water (Health Canada). Toronto's supply is nowhere near that level (City of Toronto).
Q: What does dental fluorosis look like, and can my child still get it? It shows up as small white lines or flecks on the adult teeth, and it only develops if a young child ingested too much fluoride while the permanent teeth were forming under the gums, so it can't start after the adult teeth come in (Health Canada). The Canadian Health Measures Survey found 16% of children with very mild or mild fluorosis and fewer than 0.3% with moderate or severe (Health Canada). Mild fluorosis is cosmetic and doesn't affect oral or overall health (Health Canada).
Q: What happened to children's teeth when Calgary removed fluoride? Decay got worse relative to Edmonton, which kept fluoridating. Decay in baby teeth rose in both cities from 2004/2005 to 2013/2014, with a greater increase in Calgary after cessation (Community Dentistry and Oral Epidemiology), and seven years post-cessation the social gaps in children's dental health tended to be worse in Calgary (Canadian Journal of Public Health). Calgary voters backed fluoridation 62% in 2021 and fluoride returned on June 30, 2025 (City of Calgary).
Q: What should I do instead if I don't want fluoridated water at home? Tell your dentist so the plan changes with you. Fluoride varnish applied by a trained professional prevents decay in people at risk (Health Canada), and the Canadian Dental Association supports professional varnish application for at-risk patients (Canadian Dental Association). Mention any reverse-osmosis system or unfluoridated bottled water, since the Canadian Dental Association flags those fluoride-reducing factors as part of a proper assessment (Canadian Dental Association). Then shorten the recall interval so problems get caught small.
Reviewed by Dr. Abinaash Kaur, B.Sc., DDS (University of Toronto Faculty of Dentistry), who has practised general and family dentistry in Bloor West Village for about 25 years. This article is general information about fluoride and children's oral health, not a diagnosis or advice for your child's specific case.
Worried about your child's teeth, or want a straight answer about fluoride without the argument? Bring the question to us. We're at 750 Annette Street in Bloor West Village, serving the Junction, High Park, and Baby Point. Book a family visit with The Village Dentist and we'll check your child's decay risk, look at those white spots properly, and build a plan that fits what you're comfortable with at home.
