Looking for a new watch can be a daunting task: Marketing terms can seem misleading and it’s often difficult to know exactly what a watch can handle. Nearly all watches on the market are stamped with some level of water resistance, but what exactly does this mean and why should you avoid going for a swim with your watch rated to 30m?
First thing's first: No watch is "waterproof" and you should be wary of any that is being marketed this way. This term is actually banned for being misleading.
There is always a limit to how much pressure a watch can handle.
Watches marked with a water resistance rating are sealed up to a certain pressure. Measured in atmospheres of pressure (ATM) and often converted to static depths to indicate how well the timepiece handles water.
At sea level the normal atmospheric pressure is 1 ATM.
3 ATM means the watch is sealed to 3 atmospheres of pressure, and can handle being submerged in 30 metres of static water for 10 minutes.
5 ATM : 50 metres, 10 ATM : 100 metres and so on, all the way past 100 ATM or 100 atmospheres of pressure : 1000 metres.
However, a label of "3 ATM" or "30 metres water resistance" does not mean the watch can literally survive a swim to a depth of 30 metres and you should probably keep it out of the water completely.
A watch must pass vigorous testing before being awarded a water resistance rating, but this is done in a very controlled environment, using pressurised chambers to check for breaks in the seals. These chambers can be wet or dry, but the static pressures used are not perfect representations of real water depths.
So when can I confidently wear the watch?
You may be surprised how much pressure actually acts on a moving object in moving water such as a watch on your wrist whilst swimming or diving into a pool.
Watch resistance tips
The water resistance rating on a watch applies when it is new, but temperature changes, chemicals and even time will wear a seal and reduce its ability to hold pressure - keeping water from damaging the delicate internals of your watch.
Treating your timepiece with care will help to maintain effectiveness:
- Wash your watch in fresh water after every swim and dry thoroughly to help prevent a build-up of corrosive salt.
- Remove the watch before entering a sauna - the extreme heat can cause seals to expand and create openings.
- Have the seals inspected and worn gaskets replaced at your local watch repair shop when necessary.
For a watch that can handle just about as much as you can:
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