Water Resistance: What It Actually Means

Water resistance refers to a watch's ability to withstand exposure to water — but it's widely misunderstood. Here's what you actually need to know.

Static pressure, not depth

Water resistance ratings are tested under static (still) conditions. This means the metre rating on your watch dial does not indicate the depth you can take it to — it indicates the static pressure it can sustain. Diving into a pool creates far greater dynamic pressure than a static test at the same depth, so a 50m-rated watch is not safe to take to 50 metres underwater.

Only watches marked "Diver's" on the dial are certified for diving, as they meet international standards for underwater use.

Showers, baths, spas & saunas — avoid them

Even with a water-resistant watch, heat is the enemy. Hot water causes metals to expand and contract, which can compromise the seals and allow moisture inside — potentially damaging the movement.

Understanding the ratings

Watch manufacturers use several equivalent terms:

• Metres (m) — the most common rating
• Bar — 1 bar = pressure at 10 metres below the surface
• A.T.M. (atmosphere) — 1 ATM = pressure at 10 metres below the surface

So 50m, 5 bar, and 5 ATM are all equivalent.

Caring for your water-resistant watch

• Never press the crown or pushers while the watch is wet or submerged
• If the case, crystal, or seals are damaged, the watch is no longer water resistant
• Rinse with fresh water after exposure to seawater, then wipe dry
• Have batteries replaced by an authorised or qualified professional so seals can be inspected and renewed — otherwise the water resistance guarantee is void.