Water Resistance Levels
All water-resistant watches must have the crown and function pushers completely pushed or screwed into the watch case in order to be water resistant to the specified depth. When a watch battery is changed, the gasket and seals must also be checked and/or replaced to maintain water resistance.
Water-Resistant: Watch can withstand an accidental splash of water (like rain) but should not be worn while washing hands, bathing, or swimming
Water Resistant 3 ATM (3 atmospheres, 3 bars, 99 feet): Watch can withstand daily activities and hand washing but is not intended to be submerged under water; Should not be worn while swimming or bathing
Water Resistant 5 ATM (5 atmospheres, 5 bars, 165 feet): Watch can withstand daily activities and may be worn swimming; Not intended for water activities like snorkeling or diving in a pool; Long-term exposure to water submersion is not advisable
Water Resistant 10 ATM (10 atmospheres, 10 bars, 330 feet): Watch can withstand daily activities and may be worn swimming and snorkeling; Not intended for diving to depths outside the limits of a swimming pool; Long-term exposure to water submersion is not advisable
Water Resistant 20 ATM (20 atmospheres, 20 bars, 660 feet): Watch can withstand daily activities and may be worn for most types of diving, with the exclusion of diving that requires helium gases
Water Resistant 30 ATM (30 atmospheres, 30 bars, 990 feet) & Greater: Watch can withstand daily activities and may be worn for all types of diving and water activities
Every year or so, a watch's water resistance needs to be checked to ensure it is performing to its full potential. Check the packings around the crown and back of the case. These are intended to seal the watch from water and dust. Over time, they may lose their elasticity and need to be replaced. Cracks in the crystal can also result in losing water resistance. A professional inspection can determine if any scratches or cracks are letting in any moisture.