You get to the hotel late, the bathroom is pretty, and there is a tap and a glass. Automatically, you brush and rinse. Then you remember the advice from a friend about water in certain countries and you are no longer sure.
The US Centers for Disease Control and Prevention (CDC) is clear about brushing in places where tap water may be unsafe, and it is easy to follow once you know the rule. This guide covers what the CDC says, how it fits the NHS advice on toothpaste, and a short routine that works in any bathroom. Packing tips beyond those sources are labelled as ours.
What the CDC says
The CDC Yellow Book, its health guide for international travellers, says that in many parts of the world tap water can contain bacteria, viruses, parasites and chemical contaminants. In those places it advises using only sealed commercial bottled water, or water that has been properly disinfected, for drinking, making ice, preparing food and brushing teeth. It also tells travellers to avoid getting tap water in the mouth while showering or bathing.
| Situation | CDC guidance in short |
|---|---|
| Brushing teeth where tap water may be unsafe | Use sealed commercial bottled water or properly disinfected water |
| Ice | Skip it unless you are reasonably certain it was made with safe water |
| Opening a bottled drink | Wipe and dry the outside first, since the surface may be contaminated |
| Carbonated drinks | Generally safe in unopened, factory-sealed cans or bottles; fountain drinks may not be |
| Hot drinks | Tea or coffee made with freshly boiled water is generally safe |
| Cloudy or discoloured water | May contain chemicals that boiling or disinfection will not remove; use bottled water |
The page applies where water may be unsafe. It does not say every tap abroad is dangerous, and in many countries the tap is perfectly safe. Check the specific destination.
How to find out
Before you go, read your national travel-health service’s page for the destination, and ask the hotel when you arrive. If the answer is unclear, treat the water as unsafe until you know. For a short trip, a few bottles are cheaper than a bad stomach.
A brushing routine that works anywhere
- Bottle by the sink. Put a sealed bottle and a clean cup by the basin as soon as you arrive. Wipe and dry the bottle before opening.
- Wet the brush with bottled water. A small amount is enough.
- Brush for about 2 minutes. The NHS says to brush twice a day for about 2 minutes, covering the inside, outside and chewing surfaces of every tooth, with one session last thing before bed.
- Spit, do not rinse. The NHS says to spit out the excess toothpaste and not rinse immediately, because rinsing washes away the fluoride. That also means you use almost no water.
- Rinse the brush with bottled water and stand it upright to dry in open air. Our guide to packing a damp brush in a travel case covers the drying.
- Keep your mouth closed in the shower. The CDC says to avoid tap water in the mouth.
Water flossers and other devices
The CDC says even safe drinking water is not sterile and should not be used for neti pots or contact lenses. A water flosser sprays water in your mouth, so by the same logic you would fill it only with water you would be happy to drink. That is our reading, not a CDC statement about flossers. Our travel water flosser checklist covers packing one. If you are unsure of the water, use string floss or interdental brushes for the trip; see interdental brushes for sizes.
Toothpaste and the label
The NHS says adults need toothpaste with at least 1,350ppm fluoride. In another country, check the label for the fluoride level before you buy, or bring enough of your own. Our travel oral-care kit checklist lists the rest of a compact kit.
The carry-on kit
| Item | Why |
|---|---|
| Toothbrush in a vented case | Dries between uses |
| Fluoride toothpaste | At least 1,350ppm for adults, per the NHS |
| One small sealed water bottle | Covers the first night while you buy more |
| Small towel | For wiping the bottle and hands |
| Interdental brushes or string floss | An option if you are not sure about water for a flosser |
If your trip includes a rainy-season stop, a compact umbrella earns a place in the same bag; Calm Eden’s guide on bringing an umbrella on a plane covers carry-on rules, and the Haven Umbrella folds to 40 cm (15.75 in). The same person owns FlosserGuide and Calm Eden, so the listing figures are the seller’s, not ours.
The short version
- Where tap water may be unsafe, the CDC says to brush with sealed bottled water or properly disinfected water.
- Wipe a bottle before opening it, and keep your mouth shut in the shower.
- Brush twice a day for about 2 minutes, spit and do not rinse.
- Check the destination’s water advice before you leave and the toothpaste label when you arrive.
Sources: US Centers for Disease Control and Prevention, Food and Water Precautions for Travelers, and NHS, How to keep your teeth clean, both checked 25 October 2026. This guide is general information, not medical or dental advice. If you become unwell on a trip or have a tooth or gum problem, see a doctor or dentist.
Common questions
Can I brush my teeth with tap water abroad?
It depends on where you are. The CDC Yellow Book says that in many parts of the world tap water can contain bacteria, viruses, parasites and chemical contaminants, and that in those areas you should use commercially bottled water from an unopened, factory-sealed container, or properly disinfected water, for brushing teeth. In places where tap water is treated and safe, it is fine.
How do I know whether the tap water is safe?
Check your national travel-health advice for the destination before you go, and ask your hotel. The CDC says to avoid putting tap water in your mouth unless you are fairly sure it is safe. If you cannot confirm it, use sealed bottled water.
Do I need to rinse after brushing?
The NHS says to spit out excess toothpaste and not to rinse straight away, because rinsing washes off the fluoride. That is helpful abroad, because you need less water. If you want to rinse your brush, use bottled water.
Is boiling water enough?
The CDC says hot drinks made with freshly boiled water, such as tea and coffee, are generally safe, and that cloudy or discoloured water may contain chemicals that neither boiling nor disinfection will remove. For exact boiling and disinfection steps, it points to its separate water-disinfection guidance for travellers, so check that before relying on it.
Can I use ice, mouthwash or a water flosser with tap water?
The CDC says to skip ice unless you are reasonably certain it was made with safe water, and that even safe drinking water is not sterile, so it should not be used for nasal rinsing or contact lenses. By the same logic, fill a water flosser reservoir only with water you would be happy to drink. This is our reading of its advice, not a quote.
What should I pack for brushing abroad?
A toothbrush in a vented case, fluoride toothpaste, a small bottle of sealed water for the first night, and a plan to buy more. The NHS says adults need toothpaste with at least 1,350ppm fluoride, so check the label of a local brand.
Found a source that changes the advice? Send the article URL and supporting information to hello@flosserguide.com. We welcome corrections.