Water resistance of watches: categories and legal regulations
In addition to 5 ATM, there are also the categories 3 ATM, 10 ATM, 20 ATM, etc. We will now take a closer look at what this information means, what you have to consider and what legal regulations exist for specifying the water resistance of watches.
Water resistance classification according to ISO 2281 and DIN 8310 September 2010
The standards DIN 8310 (time measurement technology – water resistance of watches – requirements and tests) and ISO 2281 regulate the criteria for the constructions and test pressures that watches have to withstand in order to be suitable for a certain water resistance.
If there is only “water resistant” on the bottom of a watch, this means that the watch is resistant to sweat, drops of water, rain, etc. in daily use. To get this designation, the watch must survive 30 minutes in 1 meter water depth and 90 seconds in 20 meter water depth without water penetrating into the case.
If there is an indication in bar or atm after the “water resistant”, then the test conditions have been tightened and the watches have a higher water resistance or water pressure resistance.
These criteria are regulated by the standards DIN 8310 and ISO 2281:
- 3 bar ≈ 3 atm (≈ 30 m): watches with the designation 3 ATM withstand a test pressure of 3 bar for a limited period and are insensitive to water splashes when washing hands or light rain. The elegant Retro Quartz watches from Circula, for example, comply with this standard.
- 5 bar ≈ 5 atm (≈ 50 m): Watches with the specification 5 ATM withstand a test pressure of 5 bar, are suitable for daily use and can be kept on when washing hands, showering and bathing. The mechanical watches of the Classic Automatic Collection, as well as Heritage Automatic and Heritage Hand-Wound, all meet this standard.
- 10 bar ≈ 10 atm (≈ 100 m): watches marked 10 ATM withstand a test pressure of 10 bar and are suitable for swimming and snorkeling.
- 20 bar ≈ 20 atm (≈ 200 m): watches marked 20 ATM withstand a test pressure of 20 bar and can be kept at a shallow depth for snorkeling and free diving. For greater water depths, watches should be tested for 30 bar (or more) water resistance.
- The Circula diving watch AquaSport meets the 20 atm standard and is also equipped with a screw-down crown for additional safety against water penetration.