Time and Tide

Your new Swiss watch is labeled “water resistant,” but what does that mean? There are varying degrees of water resistance, denoted on the watch face or back with numbers that tell you how deep you can go with your watch without incurring damage.

A watch marked simply “water resistant” is designed to withstand accidental splashes of water. Higher levels of water resistance are denoted most often in terms of meters (often abbreviated “m”). A meter is equal to 39.37 inches. One hundred meters translates into 330 feet, 200 meters into 660 feet. Occasionally water resistance levels are denoted in “atmospheres” (“ATM’s”) or “bars.” Both units are equal to 33 feet, or 10 meters.

Watches are made water resistant in two ways. All water resistant watches have gaskets, or “O” rings, that seal the watch against water. Some also have a “screw down” crown, one that can be pushed and turned into the case to make the crown aperture watertight.

It’s important to follow a few rules if you want to keep your watch watertight. First, you need to have the water resistance checked regularly: every two or three years for occasional exposure, at least once a year if you dive often. Changes in pressure while diving cause extra wear and tear on the gaskets.

Anytime the case back is opened, even if for a simple battery change, the gaskets must be replaced properly so that the water tightness is maintained, and the watch’s water resistance tested afterward. That’s why you need to take it to a service center or store with trained personnel and the right equipment. 

Do not wear your watch in a hot shower, sauna or hot tub. The heat can distort the gaskets and compromise the watch’s water resistance. Sudden changes of temperature, caused by, say, moving from a hot shower to a cold swimming pool, are especially tough on your watch because they cause it to expand and contract.

If you subject your watch to saltwater rinse your watch immediately, holding the face up to the shower head and turning the bezel (if the watch has a rotating bezel) while you do so. This will prevent salt from accumulating under the bezel and corroding the metal.

Some leather straps are water resistant. But leather straps in general are more easily damaged by exposure to water or perspiration. So for frequent exposure, buy metal.