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 a watertight seal at the joints where the crystal, case back and crown meet the case. If the watch is a chronograph, the chronograph pushers will also have gaskets. In addition 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 under water. The case must be sturdy enough to withstand pressure without caving in, in general, this means a steel or titanium case or a steel case plated with gold, manufacturers say. Solid gold cases can be water-resist provided they are sufficiently thick. A screwed down crown forms a watertight seal much like the seal between a jar and its lid.

According to guidelines issued by the Federal Trade Commission, watch marketers are not allowed to label their watches “waterproof.” Even watches designed for deep-sea diving cannot claim to be waterproof.

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 the 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 cannot be worn to the depths indicated by lab testing machines.

Watches with the 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:

  • 50 meters (1 meter is about 3.3 foot), which means the watch is suitable for swimming
  • 100 meters; indicating it can be worn snorkeling
  • 200 meters, suitable for recreational scuba diving and, believe it or not
  • 1000 meters (roughly three- fifths of a mile)

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. Some have valves that let the wearer release the helium that has seeped into the watch so the case will not explode as the watch and diver adjust to normal atmospheric conditions.

It stands for “Atmosphere” and it is equal to 10 meters of water pressure. Another word for atmosphere is “Bar” which is often used in Europe. The deeper you go, so the proportions change.

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, case dented or crystals loose or broken. That is why your watch, like a car and your teeth. needs preventive maintenance.

At least once a year. Most of the manufacturers say water resistance needs to be tested every time the case back is opened, because opening the case back can dislodge the gasket. This rule applies even to a simple battery change. (Many service centers also change the gaskets when the watch comes in for a service.) You should only take your watch to a well-known service center that guarantee work done.

There are basically two ways of machine testing water resistance, referred to as ” dry” or “wet” testing. In the former. The watch is subjected to air pressure and measurements taken to see whether the case expands as a result of air leaking into the case. If it does, the watch is not water resist. In one type of “wet” testing, the watch is first subjected to air pressure, and then submerged in water. If air bubbles come out of the case when it is underwater, it means air seeped into the watch before it was submerged, and it is therefore not water resist. In another type, the watch is placed in small water filled chamber, which is then subjected to pressure from a piston. If water gets in into the watch, it is not water resist. (This is obviously the most risky form of testing)

No. Exposing your watch to heat, whether it is in a hot tub or a sauna can cause the gaskets to loose their shape and ability to keep water out.

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

It may. Wearing a leather strap in the pool is not generally recommended. (It is like wearing your shoes when swimming) Instead, choose a metal, plastic, rubber or nylon strap However, some Strap manufacturers do offer straps that are specially treated. Check your warrantee before swimming.