Does Boiling Water Remove Fluoride?
No — boiling concentrates fluoride
This is one of the most common misconceptions about water purification, and it's worth understanding why it's wrong.
When you boil water, some of it evaporates as steam. The fluoride doesn't. It stays behind in the pot. So you end up with less water but the same amount of fluoride — meaning the concentration actually increases.
If you started with 1 litre of water at 0.7 mg/L fluoride (a typical Australian level) and boiled it down to 750ml, you'd now have water at roughly 0.93 mg/L. You haven't removed anything. You've made it stronger.
This is the opposite of what happens with chlorine, which is volatile and does evaporate when heated. People often assume fluoride behaves the same way. It doesn't. Chlorine is a dissolved gas. Fluoride is a dissolved mineral salt — a completely different chemical behaviour.
It gets worse when you cook with it
Here's a detail most people miss: when you boil food in fluoridated water, the fluoride doesn't just stay in the water — it absorbs into the food.
A 2022 study published in the Journal of Hazardous Materials found that rice and vegetables soaked or boiled in fluoridated water accumulated significantly more fluoride than previously estimated. The effect was especially pronounced at boiling temperature, where gelatinisation of rice grains and softening of vegetables increased fluoride uptake.
The researchers also noted that this effect hits infants hardest — their lower body weight means the same fluoride dose has a proportionally bigger impact.
If you're preparing baby formula or cooking rice and vegetables for young children with unfiltered tap water, boiling isn't helping. It's adding to the exposure.
Why fluoride is different from other contaminants
The reason boiling doesn't work comes down to chemistry.
Fluoride is a dissolved ion — it has fully dissolved into the water at a molecular level, like salt in seawater. You can't boil salt out of seawater, and you can't boil fluoride out of tap water.
Compare that to chlorine, which sits in water as a dissolved gas. Heat gives chlorine molecules enough energy to escape into the air. Fluoride ions don't have that escape route — they're chemically bound into the water's solution.
We covered this in detail in our article on fluoride in Australian tap water, including the sand-vs-salt analogy that explains why most filters also struggle with fluoride.
What actually removes fluoride
Reverse osmosis is the only household technology that reliably removes fluoride — forcing water through a membrane with 0.0001-micron pores that physically block dissolved ions.
Our Countertop RO achieves >99% fluoride removal and includes remineralisation so the water isn't flat or stripped of healthy minerals.
It's also worth noting: our Countertop RO has six temperature settings, from room temperature to boiling. If the reason you're boiling water is to make tea, coffee, or formula — you can skip the kettle entirely. The RO removes the fluoride first, then dispenses water at whatever temperature you need. No kettle full of concentrated fluoride. Just clean water, hot or cold.
A high-quality carbon block filter like our EcoPro Compact achieves approximately 70% fluoride reduction — exceptional for a carbon filter, but it has a ceiling that physics won't let it break through. For anyone whose primary concern is fluoride elimination, RO is the answer.
What else doesn't remove fluoride
For the full list, see our fluoride breakdown article, but the short version:
Brita/PUR jug filters — no. Fridge filters — no. UV purification — no. Alkaline ionisers — no. Leaving water out overnight — no, fluoride doesn't evaporate at room temperature either.
If a product doesn't state a specific fluoride removal percentage backed by lab testing, assume it doesn't remove fluoride.
Reverse Osmosis Countertop Water Filter
No Install • No Plumber • 99% Fluoride & PFAS Removed
