Demystifying Watch Water Resistance
Water and watches have a complicated relationship. On the one hand, a dive watch plunging to oceanic depths is an iconic image. On the other, a splash from washing your hands can sometimes spell disaster for another timepiece. The numbers stamped on your watch dial or case back – 30M, 50M, 100M, 200M – are often confusing, leading to accidental damage.
At We Clark Watch Repairs, we regularly see watches come in with water ingress, often from owners who genuinely believed their watch was safe. Let’s clear up the confusion and explain what those numbers really mean, and how our specialist equipment ensures your watch’s seals are watertight.
The Great Misconception: “Metres” Don’t Mean Depth
The biggest myth about water resistance is that the “metres” rating directly translates to the depth you can take your watch. Unfortunately, this is almost never the case for daily wear watches.
Those ratings – 30M, 50M, 100M – are derived from static pressure tests in a laboratory. This means the watch is submerged in perfectly still water and subjected to a specific pressure. However, real-world conditions are anything but static:
- Movement: Swimming, diving, or even a strong shower creates dynamic pressure that is far greater than static pressure. A forceful jump into a swimming pool can temporarily subject a watch to significantly higher pressure than its static rating suggests.
- Temperature Changes: Rapid changes in temperature (e.g., going from a hot sauna to a cold shower) can cause gaskets to expand and contract, creating microscopic gaps for water to enter.
- Ageing Gaskets: Over time, the rubber or silicone gaskets that seal your watch (crown, pushers, case back, glass) degrade, dry out, and lose their elasticity. This is the most common reason for water resistance failure.
- Damage: Sometimes, especially with daily wear watches subject to significant wear and tear, the actual metal of the case may be worn in such a way as to compromise water resistance.
A Practical Guide to Water Resistance Ratings
Here’s a general guide to what different ratings practically mean for your watch:
- No Rating / “Water Resistant”: Avoid all contact with water. Even high humidity can be an issue.
- 30 Metres (3 ATM / 3 BAR): Splash resistant. Safe for accidental splashes, rain, or washing hands – but do not submerge. Not suitable for showering, swimming, or diving.
- 50 Metres (5 ATM / 5 BAR): Suitable for light use in and around water, and fishing. Still not recommended for prolonged swimming, snorkelling, warm showering or diving.
- 100 Metres (10 ATM / 10 BAR): Generally safe for swimming, snorkelling, and surface water sports. Not suitable for scuba diving.
- 200 Metres (20 ATM / 20 BAR) / Diver’s 200m: Suitable for recreational scuba diving.
- 300+ Metres (30+ ATM / 30+ BAR): Professional diving. These watches are designed for saturation diving and more extreme underwater environments.
Crucial Rule: Never operate the crown or pushers of a watch when it is wet or submerged, unless it’s a specifically designed dive watch with screw-down pushers.
How We Ensure Your Watch Stays Water Resistant: Our Advanced Testing Process
When you entrust your watch to WE Clark Watch Repairs for servicing, especially after a battery change, gasket replacement, or any work that opens the case, water resistance testing is a critical step. We don’t just guess; we use state-of-the-art equipment to provide accurate, reliable results.
1. Our Sigma Dry Pressure Tester
We are able to conduct non-invasive “dry” testing using our Sigma pressure testing machine.
This incredible machine works by detecting minute deformations of the watch case when it’s subjected to varying air pressures. If there’s a leak, the case will deform differently as the internal pressure changes compared to the external pressure. This allows us to dry test watches at up to 300 metres water resistance equivalent without ever getting them wet. It’s perfect for ensuring the primary seals are functioning correctly.
2. Pinpointing Leaks: Our Diagnostic Wet Tester
If the dry test indicates a potential issue, or if a customer reports a known leak, we move to our specialised diagnostic wet tester. This clever device allows us to submerge the watch in water within a chamber, then carefully manipulate the pressure.
Unlike simple submersion, we can carefully observe where bubbles emerge, pinpointing the exact source of a leak – be it the crown, case back, crystal, or pushers. This precise diagnosis saves time and ensures we concentrate our efforts on the correct leak location.
3. The Ultimate Dive Test: Our Lititz Diver 125
For watches rated for use at very high depths, particularly dive watches, we can conduct a final, rigorous wet test using our Lititz Diver 125.
This robust machine can subject your watch to genuine underwater pressure, simulating real-world depths of up to 1,250 metres (125 BAR). It’s the ultimate confirmation that all gaskets are perfectly sealed and the watch can withstand its rated water resistance.
Protect Your Investment
Water resistance is not a permanent feature; it’s a condition that degrades over time. Gaskets are perishable components and need to be inspected and replaced regularly. If you use your watch in water we recommend it is checked every 12 months to confirm it is still water resistant.
Don’t wait until it’s too late and you discover water inside your watch, causing costly damage to the movement and dial. If you’re unsure about your watch’s water resistance, or if it hasn’t been tested in years, bring it (or send it) to WE Clark Watch Repairs. With our expert knowledge and advanced equipment, we’ll ensure your timepiece is ready for whatever life (or the swimming pool) throws at it!