Care
Watch water resistance: what do 3, 5 and 10 ATM mean?
· 4 min read
“Water resistant 3 ATM”: many people think they can swim with it. It is the most common mistake, and the first cause of damaged watches. Here is what 3, 5 and 10 ATM really mean, and how to protect your watch at the beach, in the shower and at the hammam.
What ATM means
ATM (or bar) is the pressure tested in a lab, with the watch standing still. In real life, a dive or a shower jet creates much more pressure. So read the figure with a safety margin.
| Rating | What you can do |
|---|---|
| 3 ATM (30 m) | Rain, splashes, washing your hands |
| 5 ATM (50 m) | A quick shower, calm surface swimming |
| 10 ATM (100 m) | Swimming, pool, beach |
| 20 ATM (200 m) and more | Snorkelling, water sports |
A 10 ATM watch can go to the beach (for example: Black Pilot — Steel Chronograph, 10 ATM), while a 3 ATM watch is a city watch, to be kept dry (for example: Classic Black Leather — White Dial, 3 ATM).
The hammam: the hidden enemy
Even a very water-resistant watch does not like the hammam. Heat and steam expand the seals and moisture can get into the case: fogging under the crystal, a rusted movement. Always take your watch off before the hammam or the sauna, as before a very hot shower.
At the beach in Morocco
- Rinse the watch in fresh water after the sea: salt damages the seals and the steel.
- Never use the crown or the pushers under water.
- Do not leave it in full sun on the towel: heat weakens the seals too.
- A leather strap does not go in the water: prefer steel or rubber in summer.
Keeping a watch water resistant over time
Water resistance is not forever: seals age. Have it checked every 2 to 3 years and at every battery change. If fog appears under the crystal, take the watch to a watchmaker quickly.
The water resistance of every watch is shown at the top of its page.
See the watchesTo choose well, also read our guide to choosing a watch.
Frequently asked questions
Can I swim with a 3 ATM watch?+
No. 3 ATM only protects against rain and splashes. To swim, choose a watch rated 10 ATM or more.
Can I wear my watch at the hammam?+
No, even if it is water resistant. Heat and steam damage the seals and moisture can get into the case. Take it off before.
What should I do if there is fog under the crystal?+
Stop wearing it and take it to a watchmaker quickly: moisture has got in and can damage the movement.
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