pH 5.5 — the line that matters
Every tooth in your mouth has an enemy: anything below pH 5.5. Below that number, enamel starts to soften and dissolve. Above it, saliva has a chance to repair the damage. That's the entire rulebook for drinks and teeth.
The published pH values of common drinks are well-documented in dental research — and some of them genuinely surprise people, particularly in the "wellness" aisle.
The three biggest surprises
- Kombucha is as acidic as Coke. Published measurements place both around pH 2.5. The fermentation that makes kombucha "good for the gut" produces acetic and lactic acid — the same kind of acid that softens enamel. The health-halo packaging tends to obscure this.
- Orange juice is worse for enamel than plain milk. Published pH for orange juice is around 3.5; plain milk sits near 6.5-6.7. Parents often swap milk for juice thinking they're upgrading — from a dental perspective they're not.
- Sports drinks are a trap. Published pH around 3.0-3.6, usually sipped slowly during exercise, with sugar. The combination makes them one of the more erosive everyday drinks. For rehydration after exercise, water or milk is significantly gentler on teeth.
Why sparkling water isn't quite innocent
Plain sparkling water (soda water, no flavour) sits close to pH 5.5 — right at the enamel threshold. Occasional glasses are low concern. But the moment you flavour it — lemon, lime, "natural fruit essence" — the pH typically drops below 4. Flavoured sparkling water behaves much like soft drink from an enamel perspective.
How to drink acidic things without damaging teeth
You don't have to give up coffee or the occasional Coke. Three specific habits make most of the difference:
- Don't sip over hours. Research on titratable acidity shows contact time matters as much as pH. A coffee finished in 15 minutes is materially gentler than the same coffee nursed over two hours.
- Don't swish it around. "Savouring" an acidic drink bathes every tooth in acid. Drink it, don't swirl it.
- Don't brush immediately afterwards. Acidic drinks soften enamel for roughly 30 minutes after you finish. Brushing inside that window scrubs softened enamel off. Wait half an hour — or rinse with water first, which buffers the pH and is almost as effective.
Rinse with water after every meal. Not just after acidic drinks — every meal. Water buffers oral pH back up within minutes, washes away food residue and sugar, and is the single most useful habit most families never adopt. It doesn't replace brushing, but it meaningfully reduces the acid-contact window between meals. Free, easy, works.
What to actually drink
Tooth-friendly: tap water (Sydney water is fluoridated, which is actively protective, not just neutral), plain milk, plain black or green tea, cheese alongside anything acidic.
Sip quickly and rinse: coffee, occasional fruit juice, sparkling water.
Reserve for occasional: Coke, kombucha, sports drinks, flavoured sparkling water, sour drinks. Not "never" — just "not every day."
If you've been a daily drinker of one of the more acidic options for years, it's worth a check to see where the enamel sits. Early acid erosion is very treatable if caught before it reaches dentine. Our check-up and clean includes an enamel assessment — book online or over WhatsApp.