Although many watches are advertised as water resistant, that doesn’t always mean you should actually go diving with them. While it’s great to be able to jump into the pool wearing you watch with 300 m (984 ft) of water resistance, that doesn’t mean you should ever dive that deep with it.
Most importantly, your precious Patek Philippe Calatrava that is “water resistant to 30 m (98 ft)” should not be used in the pool or while snorkeling! Let’s take a closer look at just what water resistance means in terms of watches of watches and how it works.
Perfect Conditions
Watches are created in factories where they are tested in a laboratory under perfect conditions. During testing, every watch is brand new and freshly assembled, and the tests are done in a controlled environment. The watch has to withstand certain pressures in both dry and wet tests. In a dry test, the watch is pressurized (or placed in a vacuum) in a small chamber. A machine then checks for even the smallest deformation or pressure change. During a wet test, the watch is placed in a water-filled cylinder. Pressure is then added to simulate depth. If the case doesn’t leak small air bubbles, the test was successful. This is how the water resistance of your watch is tested.
However, these methods of testing don’t reflect real-life conditions nor do they take a watch’s age into consideration. This is something to keep in mind when using your watch over time. Water resistance comes from a watch’s construction and whether or not it has a screw-down crown and seals. The latter plays the most crucial in your watch’s long-term water resistance. Seals are made from rubber or silicone and disintegrate over time. They can also be affected by external elements such as dirt, salt water, oils, and soaps to name a few. This is also why you should have your watch checked regularly to make sure its water resistance is still up to par.
How much water resistance do I actually need?
Below you will find an overview of the generally accepted guidelines for what a watch’s water resistance means in terms of how it can be used. Please note that this is a general list. Some watches are produced in such a way that their depth rating is the actual limit found when testing. This will be indicated by the manufacturer.
| 30 m / 98 ft / 3 ATM | Resistant to splashes and light rain |
| 50 m / 164 ft / 5 ATM | Swimming and fishing (no diving) |
| 100 m / 328 ft / 10 ATM | Swimming, and other surface water sports (e.g., snorkeling and surfing) |
| 200 m / 656 ft / 20 ATM | Jet skiing, showering, and recreational diving |
| Over 200m or marked ‘Diver’ | All of the above plus scuba-diving |
Preventing Water Damage
Regardless, it’s better to be safe than sorry when it comes to water and watches. Before entering the water, always check that the depth rating matches your planned activities. Make sure the crown is screwed down properly, and don’t use the chronograph pushers underwater if you have a chronograph. The rapid change from air to water and the pressure that comes with it puts great stress on your watch. To understand what kind of impact water can have, just think about the last time you did a bellyflop.
Keeping your watch in good condition will give you many years of enjoyment. From time to time, you may even come across images of vintage diving watches still being used for diving. This could be your watch one day if you check and maintain it the right way. Should you end up with water or condensation in your watch, make sure to visit a watchmaker as soon as you can to prevent further damage.
