Understanding water resistance ratings, pressure tests, and the impact of watch construction on actual performance.
A Comprehensive Guide to Water Resistance in Watches - Everything You Need to Know About 3ATM, 5ATM, 10ATM, and More
Water resistance in watches is one of the most important parameters that every buyer needs to understand before purchasing a new watch, especially when it comes to luxury watches or watches for daily use. In the world of watches, the term "water resistant" does not necessarily mean that you can dive with the watch – rather, it describes the watch's level of protection against water penetration under certain conditions, as tested in laboratories according to international standards.
In this article, we will delve deeply into the meaning of 3ATM, 5ATM, 10ATM and above, how pressure tests are performed on watches, and the differences between various resistance levels.
What is ATM and how is it related to water resistance in watches?
The term ATM is an abbreviation for Atmospheres. This is a unit of pressure that describes the pressure the watch can withstand during testing.
1ATM is equivalent to atmospheric pressure at sea level - approximately 10 meters of water depth, under static laboratory conditions.
If the watch states 3ATM, it means that the watch has been tested for resistance to a pressure equivalent to 30 meters of water depth under testing conditions.
It is important to understand: The numbers do not necessarily represent the actual depth at which the watch can be used. Tests are performed in a static state (without movement), while in reality, hand and watch movement create higher pressure on the seals. Therefore, ATM values should always be regarded as a guide to the possible type of activity, not as the actual diving depth.
How is a pressure test performed on watches?
Pressure testing on watches is designed to ensure that the seals and the combination of the crystal, watch case, and buttons are indeed waterproof.
The testing process usually includes:
1. Dry Test - The watch is placed in a dry pressure chamber, where a higher than normal pressure is created. Sensors detect if the watch case deforms to an extent indicating air penetration.
2. Wet Test - The watch is placed in water particles within a pressure chamber, and sometimes even in actual water. It is checked for water penetration after applying graded pressure.
3. Vacuum Test - For some watches, a negative pressure test is also performed to ensure there is no air or vapor ingress.
The tests are carried out according to international standards, specifically ISO 22810 for water-resistant watches, and ISO 6425 for dive watches.
Water Resistance Levels in Watches
3ATM - Basic Resistance (30 meters)
What it actually means: The watch can withstand light water splashes - washing hands in cold water, light rain, sweat.
What not to do: Not suitable for swimming, showering, or prolonged immersion in water, not for sauna or jacuzzi.
Who it's for: Everyday use in the office or city, where the chance of contact with water is minimal.
5ATM - Improved Resistance (50 meters)
What it actually means: Suitable for moderate water contact - rain, washing hands in cold/lukewarm water, shallow swimming in a pool.
What not to do: Not for freediving or scuba diving, and not for prolonged swimming in deep water, not for hot showers in a small, sealed room, not for sauna or jacuzzi.
Who it's for: People engaged in daily activities and light water sports.
10ATM - High Resistance (100 meters)
What it actually means: Suitable for showering without steam, swimming, shallow water sports, snorkeling, daily use even in relatively deep water.
What not to do: Scuba diving at great depths, it is best to avoid excessive steam such as in a sauna or jacuzzi.
Who it's for: Amateur athletes, beachgoers, people who want security against water ingress even with prolonged contact.
20ATM and above - Dive Watches (200 meters+)
What it actually means: Designed for professional diving, including scuba diving. Built to withstand high pressures over time.
ISO 6425 Standard: Dive watches are tested with additional tests such as resistance to shocks, magnetism, and salt.
Who it's for: Professional divers, intensive water sports.
Water-Resistant Watch Maintenance
Even if your watch offers high resistance, water resistance is not eternal. Over time, the seals wear out, and natural wear and tear can lead to water ingress.
Recommendations:
Perform a pressure test every 1-2 years.
Replace seals when opening the watch for battery replacement.