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Water Resistance In Watchmaking: Everything You Need To Know

Rolex Deep Sea Promo shot

Out of all the elements that can break your watch none does so in a more devastating fashion than water. A flooded watch can break your heart, movement, and wallet all in one little moment of inattention. Water, in fact, poses such a big threat to a mechanical watch that the success of the big daddy himself, Rolex, was based on creating some of the first water-resistant timepieces.

That is why today we will look at this segment of watchmaking more closely to gain a better understanding of everything that surrounds the topic of water resistance.

Let’s get into it!

Why do we need water resistance in watches?

Let’s start off with why we need water resistance. What actually happens to a watch when water enters its case? The first, most obvious, thing that will happen is that the movement of the gears inside will be impaired.

If you imagine all the different oils required to lubricate the moving parts of a watch then you can imagine how water will add friction either by replacing the air or washing away the oils. This will increase the wear on the moving parts as well as hinder timekeeping capabilities. The problems though don’t stop there.

The dial is particularly delicate

While most parts of a watch are made out of metal and will not get damaged straight away your dial is significantly more delicate. If an hour hand gets stained it can easily be polished to look like new again, but if your dial is messed up that may not ever be completely repaired forcing you to potentially have to replace it with a new one.

Risk of rust

The biggest damage, however, happens to the internals when exposed to water for too long: rust. Rust can occur regardless of whether fresh or salt water is in the movement, though it happens much faster with salt. While rust on something like a car can usually be repaired without having to replace parts on a movement this is different.


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Since the many different parts are so small there is simply not enough material for a repair and they can get completely corroded in a matter of days. Therefore one of the first things to learn is that if you see hints of water inside your watch, like for example fog forming under the crystal, it is a good idea to go to your watchmaker sooner rather than later. Your wallet will thank you.

How does water resistance work in watches?

Having established why we need water resistance, let’s see how it actually works. To start things off on a simple note most watches are made out of stainless steel which is waterproof. Pretty obvious right? But that knowledge is required to understand that any opening to a watch case poses a risk for water to enter through it.

On a typical watch you will have multiple of these including, but not limited to, the crystal, caseback, winding crown, and pushers on a chronograph for example.

The crystal

Let’s look at the crystal first. A crystal can crack under intense pressure, but a much more likely issue is that they were not properly sealed in. That is to say, a good watchmaker who tests a watch goes a long way to ensure some peace of mind.

A general rule of thumb is that the thicker the crystal the more pressure it can take, as can be seen from the Rolex DeepSea Special. An interesting alternative way to approach this issue can be seen from the Russian Vostok Amphibia.

vostok amphibia 13 min

While a normal crystal stays static the Amphibia has some flex in the design which allows the crystal to be pushed in with increased pressure which actually increases its resistance the deeper it goes.

The caseback

Next there is the caseback. Most watch designs which care for waterproofing will have a screw down caseback and a rubber gasket ensuring the watertight seal. Since it is made out of metal it won’t shatter, like the crystal, but it can bend which can damage any moving parts in the movement.

While an unlikely scenario it is more probable for your caseback to bend than your crystal to shatter. Again, thicker means better and special dive watches tend to have reinforced casebacks. A clever solution to this problem was shown by the original Omega Ploprof.

It simply did not have a caseback (remember that holes are the problem) and sacrificed ease of access to the movement for an incredibly structurally secure design.

The crown

The most vulnerable hole in a watch design is that of the crown. Now the crown is much more delicate than the crystal or caseback for a multitude of reasons. In principle it works similar to the caseback.

The waterproofing works through means of being screwed on in tandem with one, or multiple, rubber gaskets. The major difference is that the caseback gets screwed on for you while with the crown you have to do so yourself. This leads us to the number one cause of water damage to watches: people forgetting to screw on the crown properly. This nightmare scenario has murdered countless precious watches already, so don’t let yours be one of them.


Another hole that you may have to look out for depending on your watches are pushers, most commonly for a chronograph watch. While some people refuse to bring a chronograph, regardless of its water rating, close to any form of liquid it is good to clear up some misconceptions.

The biggest one is that screw down pushers ensure a watch’s water rating. This is not necessarily true for all watches. The Rolex Daytona, a commonly cited example for this, has watertight seals inside the pushers and the screw down element does not directly relate to the water resistance.


What a screw down pusher can do is indirectly make it water-proof by preventing you from accidentally pressing the pushers. During activation of a pusher there is the potential for water to enter the movement while the seal is broken. While there are some rumours of a french diving team who have tested a Daytona some 30 meters under water the truth is you are better off staying on the dry side and only using your chronograph when far away from the cool wet.

There are special chronographs that can be used underwater but those are far and few in between because the fact of the matter is that for underwater timing a dive bezel is the smarter, and safer solution.

How different liquids impact your watch

Having dealt with all the potential threats to the integrity of a watch case let’s talk about how the different liquids impact your watch. While it may be trendy to pour coffee and all kinds of other drinks on your watch for our sake we focus on water.

Fresh water

The most common type of water your watch will encounter is fresh water like that from your shower.

Regarding fresh water there really is nothing for you to bear in mind except for the normal precautions of having
your watch regularly pressure checked by a watchmaker and making sure you screwed in the crown.

Salt water & chlorinated water

The story changes when talking about chlorinated water or salt water. For both of these it is recommended that you wash off your watch with fresh water afterwards.

That is because over a long time period they may corrode your seals particularly for vintage watches.

Water temperature

Finally, the temperature of the water has an impact too. While some people consider hot tubs a killer for a watch that makes little sense since the temperature is similar to body temperature.

What can be harmful for your watch though are extremes like boiling water or throwing your watch into snow. Extreme temperatures and particularly a fast change between them causes the materials inside to expand or shrink to a point where they can potentially break.

Water resistance ratings for watches

To finish things off let’s touch on water resistance ratings. There is already enough information out there that does a good job translating what the respective rating actually means.

water resistance chart

Water resistance chart source: Watches2U

Something that they do not tell you, is that you should use some common sense when figuring out the limits of your watch. If, for example, you own a modern Rolex with the standard 100 meters of water resistance I would feel comfortable wearing that watch up to 100 meters of depth.

If you have a vintage Patek, on the other hand, with a theoretical rating of 30 meters I would become uneasy wearing it in heavy rain. Always consider the brand, build, and age of a watch when interpreting a water resistance rating.

The bottom line

If you take all these things into account, there really isn’t much that can go wrong. I know there are people who take their submariner off when showering and that is fine. Don’t forget though that you own your watch, and it doesn’t own you. Enjoy the beach and don’t let fear of breaking your watch ruin your fun. Just don’t forget to screw in your crown!