Waterproof vs. Water Resistant in Watches: A Full Guide

In your experience of buying a timepiece, you definitely have heard the terms waterproof and water-resistant. The question is how they exactly differ from each other while both clearly have the term ‘water’. The majority often uses the terms interchangeably despite not meaning the same at all.

In a simple definition, waterproof as the name implies should be impenetrable to water while water resistance is on another level. It refers to the watch’s capability to be worn underwater and withstand water pressure to a certain extent.  It’s considered crucial to know how the difference between waterproof and water resistance, especially if you intend on buying a dive watch. 

Waterproof Watch vs. Water-Resistant

Water is inevitable in our daily life, we can’t always avoid light splashes of water when washing our hands or when rain is suddenly pouring. Therefore, we need watches with enough resistance to water. Some people also put water resistance as an important consideration in buying timepieces. So, what is the difference between water resistance and waterproof watches?

Water resistance ensures the wearer to what extent the watch can withstand water pressure. Every watch from every brand would have different ranges from 1 ATM (10 meters) to 30 ATM (300 meters) and even higher, such as the Omega Seamaster Dive watch. 

Meanwhile, a waterproof watch refers to timepieces that should be impenetrable by water or it wouldn’t leak under any circumstance. In other words, there isn’t any moisture that can permeate the watch case and get into the movement parts. However, every fine watch on Earth would still permeate throughout time due to the aging process and constant exposure to extreme conditions. 

In many cases, the seals designed to protect the gapless construction will degrade. The seals are normally made of plastic or rubber. The quality will decrease over time in extreme cold or heat. Therefore, your watch needs to be regularly serviced every two years to ensure the seals function as they should be.  

How to Read Water Resistance Ratings in A Watch

These days, every watch brand includes water resistance information in the caseback. The wearer can easily indicate the ratings and know how to treat the watch. But, is it that easy to read the water resistance in a timepiece? Unfortunately no.

There is another thing to understand behind the water resistance number in our watches. While you might expect a watch with 100m water resistance would perfectly work for 100m diving activity, this is not actually a good thing for your watch. Indeed, the watch passed a leakage test for a static test pressure of 100m but it couldn’t stand the pressure for extended periods. 

Little know that when talking about waterproof watches vs water resistance, the number marked in a watch actually works at a fraction of its indicated rating. For example, watches with 200m water resistance should actually be worn at 200m for a short period to avoid water leakage or other damage.

Read also: How to Use Dive Watch Bezels: A Simple and Thorough Guide

Water Resistance Standards Regulation

Some standard regulations have been settled to manage an appropriate number for water resistance in watches. In this case, there is a term ATM known as atmosphere or meters. The number indicates that 1 ATM is equal to 10 meters. Below are the common water resistance ratings in a timepiece:

• 50M/165 ft: safe for showering.
• 100M/330 ft: safe for swimming in shallow water.
• 300M/1000 ft: safe for scuba diving.
• 1000M/3000 ft: safe for deep sea diving.

As for the standards regulations, there are ISO 2281 and ISO 6425 that many watch brands look into when it comes to water resistance testing.

ISO 2281

The International Organization of Standardization issued water resistance regulations in 1990. ISO 2281 has been implemented in many countries. It consists of regulations for tests to determine the water resistance in a timepiece, such as condensation tests, air resistance tests, water pressure resistance tests, and others.

Those tests will be done on a random sample from each batch of watches. In addition to these regulations, the term “waterproof” is also banned to describe a watch by the International Organization of Standardization.

ISO 6425

After a few years, ISO 6425 is also announced in 1996 to describe watches that can handle depths of at least 100m. The test consists of condensation tests, reliability tests, pressure tests, saltwater tests, and others. In addition, certain dive watches are also regulated for mixed-gas diving functions for diving with assistance from a diving chamber. 

Final Thought

As explained in the article above, waterproof watch vs. water-resistant is two different terms that define the different conditions as well. We can also conclude that waterproof alone in a watch doesn’t guarantee enough protection as it is only impenetrable to moisture without any leakage – it hasn’t been used in official standards as well.

On the other hand, water resistance is the one that appears reliable in the watchmaking industry. It also has been regulated by the ISO 6425 and ISO 2281 standards. In accordance with that standards, it’s suggested to buy a timepiece with a minimum 10 ATM rating or 100m water resistance. 

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