No watch is truly waterproof; every watch is only water resistant to a stated limit. “Water resistant” means the case can keep water out under specific test conditions, up to a rating such as 30, 100, or 300 meters, while “waterproof” implies absolute protection that does not exist in watchmaking. That is why regulators such as the US Federal Trade Commission have discouraged the word on watch labels.
Quick answer: Treat “water resistant” as a rated limit, not a promise. A 30 m watch is fine for splashes and rain, 50 to 100 m is fine for swimming, 200 m suits recreational scuba, and 300 m and up is for serious diving. Gaskets age, so even a diver should be tested regularly.
Water resistant vs waterproof: the core difference
Water resistance describes how well a sealed case, crystal, and crown keep water out. It is measured, rated, and limited. “Waterproof” suggests nothing can ever get in, under any conditions and forever. Because seals wear, crowns get left unscrewed, and pressure changes, that claim cannot be guaranteed. The FTC has long taken the view that the word “proof” suggests an absolute measure of protection that does not exist for watches, and the industry standard label became “water resistant.” Sources differ on the exact year of that guidance, so the point to remember is simply that you will see “water resistant” on legitimate watches.
What the numbers mean in real life
Ratings are shown in meters, bar, or ATM (atmospheres). One ATM is roughly 10 meters. Here is a practical guide, using conservative advice similar to what many brands publish.
| Rating | Equivalent | Fine for | Avoid |
|---|---|---|---|
| 30 m | 3 ATM | Splashes, rain, washing hands | Swimming, showering |
| 50 m | 5 ATM | Light showering, surface swimming | Diving, water sports at speed |
| 100 m | 10 ATM | Swimming, shallow snorkeling | Scuba diving |
| 200 m | 20 ATM | Recreational scuba diving | Saturation or deep diving |
| 300 m and up | 30 ATM and up | Professional-level diving, serious water sports | Using it with the crown unscrewed |
Some experts note that even 30 m watches survive casual swimming when new and well maintained, but brands rarely recommend it. If you plan to swim regularly, buy a watch rated 100 m or more.
Why a “50 m” watch is not rated for 50 m of depth
Ratings come from laboratory tests in which a case is held at pressure under still conditions. Real life is harsher: a swimmer’s arm moving through water, a dive into a pool, or a jet in a shower adds dynamic pressure that can exceed the equivalent static pressure. That is why a watch rated to 50 m should not go to 50 m deep, and why higher ratings are recommended for activities involving movement or impact.
The standards behind the labels
- ISO 22810 covers water-resistant watches in general. It sets out how brands test and label watches for everyday water exposure.
- ISO 6425 covers divers’ watches. It sets stricter requirements, including tests at pressures above the rated depth, plus rules for legibility, bezels, and shock resistance, which is why a “diver’s” label means more than a bare depth number.
Not every watch is certified to these standards, and some brands test their own way. A marketed depth does not guarantee compliance, so check whether the watch is described as ISO-compliant if that matters to you. Our guide to the best diving watches highlights models built to dive standards.
What actually keeps water out
Gaskets
Small rubber or synthetic rings seal the crystal, caseback, crown, and pushers. Over time they can dry, flatten, or crack, and heat, chemicals, and friction accelerate that. Gaskets are the most common reason an older watch leaks.
The crown
A screw-down crown threads into the case tube like a bottle cap, making it far more secure than a push-pull crown. Many leaks happen because the crown was left unscrewed or pulled out. Some brands use extra gaskets or locking levers for more protection.
The crystal and case design
A well-fitted crystal in a solid case matters as much as the gaskets. A knock can loosen the fit, which is why a watch should be inspected after a hard impact.
Everyday situations
- Showering: A watch rated 50 m or higher should handle it, but soap and shampoo can degrade gaskets over time. Many owners simply take the watch off.
- Hot tubs and saunas: Avoid them. Heat can stress seals, and hot water and steam can enter more easily. This is the conservative advice from most manufacturers.
- Swimming: 100 m or more is a sensible minimum, and do not press buttons or turn the crown underwater.
- Salt water: Rinse the watch with fresh water afterward, and keep a screw-down crown fully tightened.
- Leather straps: Leather and water do not mix well. A rubber, metal, or nylon strap is a better choice for wet activities.
Common mistakes that cause leaks
- Leaving the crown pulled out. A crown that is not pushed in or screwed down is an open door for water.
- Pressing chronograph pushers underwater. Unless the maker specifically allows it, pushers are weak points when wet.
- Assuming an old watch still meets its rating. A watch that was fine 15 years ago may have dried-out seals today.
- Skipping a pressure test after a battery change. Opening the caseback disturbs the seal, and a careless reseal can undo the rating.
- Ignoring knocks. A hard hit can shift a crystal or bend a case tube without any visible sign.
Diver’s watch vs a water-resistant watch
A diver’s watch is built and tested to a stricter standard, ISO 6425, and usually has a screw-down crown, a unidirectional rotating bezel, strong lume, and a depth rating well above what a diver will use. A general water-resistant watch might have a similar number on the dial but is designed for swimming and daily life, not for time-limited dives. If you plan to scuba dive, buy a true diver’s watch; if you simply want a watch that can handle pools and rain, a 100 m rating is plenty. Affordable dive-style options are covered in our Submariner homage roundup.
How to read the dial and caseback
Most brands print the rating on the dial or caseback in one of three forms: meters (for example, “100 m”), bar (“10 bar”), or ATM (“10 ATM”). Sometimes it appears as feet, such as “330 ft.” These all describe the same idea. Look also for the words “water resistant” and any mention of a standard. A watch with no rating at all should be treated as splash-resistant at best, and you should keep it away from swimming pools and the shower.
How to keep your watch water resistant
- Test it every year or two. A watchmaker can pressure-test the case in minutes.
- Replace gaskets during service. Any time a case is opened, such as for a battery change, ask for gasket replacement and a pressure test.
- Check the crown. Make sure a screw-down crown is fully screwed in before swimming.
- Do not operate pushers underwater unless the maker says it is safe.
- Do not rely on a rating after damage. A crack, a dent, or a loose crystal means it needs inspection.
If you do your own battery changes, a proper tool set helps; see our guide to the best watch repair kits, but note that resealing a case correctly usually needs a pressure tester.
Water resistance and case materials
The material of the case does not by itself determine water resistance; design and sealing do. Both stainless steel and titanium cases can be made highly water resistant. For a comparison of the two metals, read our guide on titanium vs stainless steel watches.
FAQ
Is water resistant the same as waterproof?
No. Water resistant means the watch resists water up to a limit; waterproof implies total protection, which no watch can guarantee.
Can I swim with a 50 m water-resistant watch?
Many people do, especially on the surface, but a 100 m rating is a safer minimum for regular swimming because moving through water adds pressure.
Can I shower with a water-resistant watch?
Usually yes if it is rated 50 m or higher, but soap and hot water can wear gaskets faster, so frequent showering with a watch is not ideal.
Does water resistance last forever?
No. Gaskets age and wear, so have the watch tested periodically, especially if you swim.
What does ATM mean on a watch?
ATM stands for atmospheres. One ATM is roughly 10 meters, so 10 ATM means about 100 meters.