A Must-Read Guide to Watch Water Resistance

　　2, To ensure the water resistance of a replica watch, the crown must be locked tightly.

　　3, If water accidentally enters the watch, it should be sent to the after-sales service centre in time to avoid damage to the movement.

　　4, It is recommended to have a comprehensive service for the watch every 2-3 years and replace the waterproof seals to ensure water-resistance performance.

　　In daily life, most people assume that if a watch is marked as water-resistant, it can be submerged in water or worn whilst swimming. However, this is not the case. The water resistance markings on watches fall into different categories. Does the stated water resistance depth mean you can submerge the watch in water to that exact depth? Thinking so is an even greater misconception.

　　Water resistance ratings are based on room-temperature environments. When the temperature rises, the permeability of water molecules increases significantly. Furthermore, thermal expansion and contraction cause watch components to expand and contract to varying degrees, widening the gaps between parts and potentially causing the water resistance to fail completely. Therefore, never wear your watch whilst taking a bath or shower, visiting hot springs or saunas, or experiencing sharp temperature changes.

　　A watch is not a hermetically sealed case, so a water-resistant watch is not resistant to water vapour. Water molecules in the air enter the case along with air. If humidity is high, the temperature difference between the inside and outside can easily cause a layer of condensation to form on the crystal glass. This is just like seeing mist condense on car windows on foggy or rainy days. Strictly speaking, this situation does not count as water ingress.

　　How to understand water resistance markings on a watch

　　Watches that only state "Water Resistant" without a numerical rating are considered equivalent to 20-metre water resistance under international standards, which equals 2 ATM. Its actual meaning is to keep your watch away from water as much as possible.

　　Watches marked “3 ATM” or “30M” mean 30 metres of water resistance. These watches can be used normally when exposed to small splashes or light raindrops.

　　Watches marked “5 ATM” or “50M” mean 50 metres of water resistance. You can wear the watch while washing your hands or face, and brief exposure to cold running water from a tap should not pose a problem.

　　Watches marked “10 ATM” or “100M” mean 100 metres of water resistance. Only watches with this rating can be submerged without suffering water ingress, allowing you to wear them whilst swimming, surfing, or snorkelling.

　　Only when a watch is marked “20 ATM” or “200M” and above, and complies with international ISO standards, is it genuinely suitable for diving. The replicas produced by N Factoryreplica Rolex Submariner series watches, all feature 100 metres of water resistance, with some models even reaching 200 metres of water resistance, presenting no issues whatsoever even when swimming.

　　It is worth noting that to ensure water resistance under any circumstances, the crown must be fully secured (push-pull crowns pushed in, screw-down crowns screwed tight). Discussing water resistance without a fully secured crown is pointless.

　　Why is there such a large difference between the stated water resistance depth and actual real-world use? Standard pressure tests are merely static measurements, applying the rated pressure for just a few seconds. However, in actual wear, accompanied by frequent hand movements, the environment surrounding the case is dynamic and experiences changing pressures. Over time, exposure to sun, rain, dirt, and dust causes the rubber gaskets inside the case—and even the case itself—to age gradually, altering the water resistance performance accordingly.