Water Resistance


There are several features that help make a watch water-resistant. The most important is the gaskets, or O-rings – made of rubber, nylon or Teflon which form watertight seals at the joints where the crystal, case back and crown meet the watchcase. If the watch is a chronograph, the chronograph pushers will also have gaskets. In addition, some water-resistant watchcases are lined with a sealant, applied in the form of a quick hardening liquid, which helps keep water out. The thickness and material of the case is also a big factor in determining whether a watch can safely be worn underwater. The case must be sturdy enough to withstand pressure without caving in.

In general, this means a watch with a screw-in case back, as opposed to one that pushes in, also contributes to a watch’s water resistance. A screw-in crown, a feature of many divers’ watches, helps prevent water getting into the case through the watch stem pipe. When it is screwed down it forms a watertight seal much like the seal between a jar and its lid.


Q. A watch is labeled “water-resistant to 50 meters,” but the manufacturer’s instructions say you can only wear it swimming, not snorkeling or diving. Why is that?

A.The different levels of water resistance as expressed in meters are only theoretical. They refer to the depth at which a watch will keep out water if both watch and water are perfectly motionless. These conditions, of course, are never met in the real swimmers or diver’s world. In real life, the movement of the wearer’s arm through the water increases the pressure on the watch dramatically; so it can’t be worn to the depths indicated by lab testing machines.


Q. What are the various levels of water-resistance?

A. Watches with lowest level of water resistance are labeled simply “water resistant.” They can withstand splashes of water but should not be submerged. Above that (or below it, literally speaking), the most common designations are; 30 meters, it is not recommended these watches are immersed, they are only splash resistant. 50 meters (1 meter is about 3.3 feet), which means the watch is suitable for light swimming; 100 meters – indicating it can be worn for snorkeling; 200 meters – suitable for most water sports including scuba diving; 1,000 meters – watches in this last category can endure deep-sea diving. Their gaskets are made of materials that can withstand the helium used in decompression chambers. Keep in mind that the depth specified on the watch dial represents the results of tests done in the lab, not in the ocean.


Q.The abbreviation ATM used in labeling degrees of water resistance. What does it mean?

A. It stands for “atmosphere” and 1 ATM is equal to 10 meters of water pressure. Another word for “atmosphere” is “bar”, which is often used in Europe.


Q. Is water resistance permanent?

A. NO. Water resistance depends on several factors (see question 1), some of which can be affected by wear or simply by time. Gaskets can become corroded or misshapen, cases dented or crystals loose or broken. That’s why your watch, like your car, needs preventive maintenance.


Q. How often does water resistance need to be checked?

A. At least once a year. Most manufacturers say water resistance needs to be tested every time the case back is opened, because opening the case can dislodge the gaskets. This rule applies even to a simple battery change. Our service center changes the gaskets whenever a watch comes in for service.


Q. Can you wear a water-resistant watch in the hot tub?

A. NO. Exposing your watch to heat, whether it’s in a hot tub, shower or sauna can cause the gaskets to lose their shape and their ability to keep out water.


Q. What besides extreme temperatures will jeopardize a watch’s water resistance?

A. Some chemicals can corrode the gaskets and make it vulnerable. Heavily chlorinated water can cause problems, as can spray-on perfumes, deodorants and hairsprays, they can work their way into the watch’s seams and damage the gaskets. (They can also damage your watch’s finish.)