Water resistance is actually the wrong term because no watch is absolutely waterproof. The official term is “water resistance” or “water resistant”.
Gradations of waterproofness:
No mention of water resistance. Your watch is not waterproof. So even look out with splashes and rain water or perspiration
3 ATM/3 Bar/30 meters:
Your watch is resistant to splashing and rainwater or perspiration. The watch is not suitable for swimming.
5 ATM/5 Bar/50 meters:
With your watch, it is possible to swim on the surface (we advise you not to swim with a 5 ATM watch) or take a shower, if there are no temperature differences! The watch is not suitable for diving!
10 ATM/10 Bar/100 meters:
This watch can be used with most water sports such as swimming, diving (in the pool), snorkeling or sailing, if there are no big differences in temperature! The watch is therefore not suitable for scuba diving or recreational diving, in addition, large differences in temperature should be avoided!
20 ATM/20 Bar/200 meters:
Your watch is water resistant in all forms of water sports and recreational diving (up to 30 meters).
100 ATM/100 Bar/1,000 meters:
Your watch is suitable for scuba diving.
Taking into account that the depth indicated on your watch is the result of laboratory tests at room temperature. Due to different circumstances, the depth that is mentioned is not a reflection of reality! A watch with a water resistance of 3 ATM/3 Bar/30 meters is certainly not suitable for swimming or diving.
Temperature differences are an unfair factor that causes a lot of leaks in watches. When the watch is heated in one way or another (for example by hot showers, a sauna or a tropical climate), the temperature of the cabinet can reach 40 or 50 degrees Celsius. When the watch suddenly comes in contact with water with a temperature of 20 to 25 degrees Celsius, the case of the watch gets a huge blow due to the difference in temperature. A wardrobe that is not made for these circumstances can then leak and fill with water.
Keep your watch waterproof: using your watch (rubber) the joints can wear and dry. Let your watch undergo a water resistance test every 2 to 3 years. If you use a professional diver, you must have your watch tested at least once a year.
Check regularly that the glass of the watch is not scratched.
If the watch has been in contact with salt or chlorinated water, it should be thoroughly rinsed with fresh water or tap water and dried with a cloth.
Avoid significant temperature differences (a hot shower or sauna, and even the heat of a hair dryer can suffice to blow the case of the watch so that it is no longer waterproof).
Have your watch checked regularly by an official dealer or an experienced watchmaker.