The term water resistance refers to the watch's ability to withstand splashes of water to varying degrees. Water resistancy is tested in "still", or static, conditions. So, if you dive into a pool wearing a watch which is 50 metres water resistant, the pressure impacted upon the watch on hitting the water will be far greater than that experienced at a 50 metre static test. Therefore, the number of metres shown on a watch face does not indicate the depth that the watch can be taken to, but rather the static pressure it can sustain.
Only watches marked "Divers" on the dial should be used for diving, as they fully comply with the international standards for divers watches.
Watch manufacturers use other terms to measure water resistancy:
- A.T.M. (atmosphere), where 1 A.T.M. is the equivalent to pressure at 10 metres below the surface
- Bar, where 1 bar is equivalent to pressure at 10 metres below the surface.
Caring for a Water Resistance Watch:
- The buttons on a water resistant watch must not be pressed whilst the watch is under water or still wet.
- Do not pull out the winder whilst the watch is under water or still wet.
- If the case, glass or seal is damaged, the watch should no longer be regarded as water resistant.
- If a watch is exposed to seawater, it should be washed well in fresh water and wiped dry.
Batteries should be changed by the manufacturer or approved service agent so that the seal can be checked and renewed if necessary. If this is not done, the watch will no longer be guaranteed water resistant.