Many customers ask us if their watch is waterproof. The short answer is no, it is not. Watches can be water-resistant which will generally mean that they have a mark indicating the degree of water-resistance to which they have been tested (this mark is usually BAR, ATM, meters, feet or a combination of these). Something to keep in mind is that the laboratory tests which watches undergo use static pressure which is different from the actual water pressure on a watch during real world activities.

Water-Resistant vs. Waterproof

Before getting into the nitty gritty of what “water resistance” even entails we need to highlight one important thing that must always be kept in mind; Water resistant is not waterproof.

As a matter of fact, when it comes to devices, be they watches or consumer electronics, there is no such thing as waterproof. Every device, including a watch, no matter how carefully engineered, has a failure point. Every smartphone, smartwatch, wearable, “waterproof” camera, even submarine, everything, has a point where a combination of water temperature, depth, length of exposure, or manipulation of the device while submerged, will lead to a failure of the water-resisting mechanism(s) and the device will no longer be water resistant.

It is fair to say, that not only is there no such thing as waterproof, but that even most instances of “water-resistant” are poorly marketed, poorly understood, and work poorly under real world conditions.

Let’s start off by exploring the atmosphere (ATM) rating since it is both the most common and the most applicable to watches and see how this rating applies in the real world.

Understanding the ATM Rating

Long before anyone even considered taking cameras in pools or phones out on a jet ski ride, people were wearing their wristwatches to the beach. The ATM, or atmosphere rating is used to denote how much static atmospheric pressure a device can endure when submerged. The higher the ATM rating, the deeper the device can go, as deeper water exerts more pressure. The ATM pressure/water resistance rating is the one most often found on regular mechanical and battery driven watches.

One ATM translates to the static pressure exerted by static submersion in 10 meters of water. The following chart outlines common ATM ratings for consumer watches and wearables. Because the meter rating translates easily from ATM to metres (1ATM = 10 metres) we have added the pressure value in feet for the convenience of those unused to the metric system.

As a reference point to help understand the chart, at sea level you are already at 1 ATM. This is why a watch (or device) with a 1 ATM rating offers no submersion protection or general water resistance. Simply putting a watch under the surface of a body of water immediately exposes it to a slight increase in pressure and for many watches that is more than enough to allow water to enter.

Furthermore, as mentioned, these ratings are for static pressure. This means if the watch is sitting perfectly still in a test chamber it can endure pressure up to the rated value and then, upon removal from the test chamber it will function. Any application of dynamic pressure caused by movement of the wearer (such as swimming, diving into a pool, falling off a jet ski, etc.) increases the pressure of water exposure. That is why a watch that is rated for 3 ATM and would survive a rainstorm, will end up damaged if it is sprayed with a high-pressure water hose.

Rating	Pressure	Suitable Use / Precautions
1 ATM	—	Poor water resistance. Device should be kept away from water.
3 ATM	~100 feet	Suitable for everyday use. Protected against splashes, rain, water exposure during hand washing, and so on. Not for swimming.
5 ATM	~150 feet	Suitable for short periods of submersion like light swimming.
10 ATM	~330 feet	Suitable for extended periods of submersion such as snorkeling.
20 ATM	~660 feet	Suitable for high impact water sports like surfing, jet skiing, and shallow dive trips.
Diver	>660 feet	Rated dive watches, governed and rated by ISO 6425.

Since there is no official body that conducts ATM tests and enforces adherence to guidelines, the rating is unofficial. Watches rated from 1-20 ATM are labeled as such by the manufacturer and not always labeled in a way that adheres with the common conventions used by other manufacturers.

As was highlighted above, there is no such thing as waterproof. There is water-resistant, under controlled test parameters, but the reality is that even a water-resistant watch really only resists water as long as it stays within the water exposure length, temperature, and depth parameters outlined by its ATM rating and the manufacturer’s specifications.