What Does Watch Water Resistance Mean? A Guide for Custom Watch Makers

Watch Water Resistance
What does watch water resistance ratings actually mean? How are they tested? This ultimate guide covers everything from definition to real-world impact for different water resistance levels.

Table of Contents

Water resistance is one of the most important yet often misunderstood attributes of watches. As a professional custom watch maker based in China, we at Romlicen frequently receive questions from clients about what watch water resistance ratings actually mean.

This common confusion is completely understandable – the various meters-based ratings like 30m, 50m, and 100m don’t intuitively give a sense of how much water exposure a watch can actually handle. Additionally, factors like wear-and-tear can compromise water resistance over time if the watch isn’t properly cared for.

In this comprehensive guide, we aim to impart a clear understanding of what watch water resistance ratings signify, how these ratings are tested and verified, and what you need to keep in mind for real-world water exposure. We’ll also share expert perspectives from our experience of manufacturing OEM and ODM watches for clients across the globe.

As China’s foremost custom watch maker trusted by brands worldwide for our quality and reliability, maintaining high water resistance standards is a cornerstone of every watch we produce. This article will give you the knowledge you need to choose the right water resistance for your custom timepiece, whether it’s a daily wear fashion accessory or a performance sports watch made for underwater use.

Water Proof Watch

What is Water Resistance for Watches?

Water resistance refers to how well a watch withstands exposure to water. This includes both accidental water exposure, like getting caught in rain or dropping the watch in water, as well as intentional submersion for swimming and diving activities.

Watch water resistance ratings represent the depth to which a watch is proven to be water resistant under test conditions. Some common ratings are:

  • 30m – Can withstand splashes of water or getting caught in the rain, but not suitable for swimming or diving
  • 50m – Can be worn swimming, but not for high velocity water sports like water skiing
  • 100m – Suitable for recreational swimming and snorkeling
  • 200m – Appropriate for serious surface swimming and recreational scuba diving
  • 300m+ – Withstands professional diving activities and saturation diving

Do note that real-world water exposure depends on multiple factors, which we will cover later in this article. As a rule of thumb, it’s advisable to pick water resistance well beyond the maximum depth needed. For example, watches with 100m rating are best for casual swimmers, while those with 200m+ rating would be more suitable for diving.

In our experience manufacturing custom OEM and ODM watches, we at Romlicen always ensure that the water resistance meets or surpasses the client’s requirements based on the intended activity. Contact us today to create your custom dive watch engineered for underwater performance.

Water resistant watch

Watch Water Resistance Chart

The water resistance ratings for watches are measured in terms of atmospheric pressure, abbreviated as ATM. Each increase in ATM value indicates the watch case and seals can withstand water pressure equivalent to being submerged to greater and greater depths before leakage occurs.

To give more tangible context, a watch with a 3 ATM rating can handle splashes, rain, and hand washing; 5 ATM allows for surface swimming and showering; 10 ATM enables recreational scuba diving up to 100 feet; and 20 ATM makes it suitable for high-velocity water sports and saturation diving.

By equating the ATM ratings to real-world water exposure examples, it aims to help readers intuitively understand what level of water resistance is suitable for their intended use case. Please let me know if you need any clarification or have additional suggestions!

Watches Water Resistant Cart
Watches Water Resistant Cart

0ATM/0 BAR/O M/0ft

Watches with 0 ATM water resistance rating are not designed for any contact with moisture whatsoever. Even exposure to humid environments or hand washing should be strictly avoided. However, certain disingenuous watch manufacturers may creatively market 0 ATM watches as being “water resistant” under hopes customers do not understand the technical difference. When selecting a watch for applications requiring water protection, it’s vital to verify the ATM rating aligns with the intended conditions of use.

1ATM/1 BAR/10 M/33ft

Watches with 1 ATM rating are tested to handle water exposure up to 10 meters in depth. This makes them suitable for withstanding occasional rain or minor splashes. However, 1 ATM watches cannot be intentionally submerged for activities like swimming or bathing. Typically, very affordable watches made using plastic or alloy will have 0-1 ATM resistance purely for basic moisture protection. While 0 ATM models do not undergo official testing, 1 ATM watches must be checked to verify they meet the stated pressure rating using water ingress inspection equipment. This confirms the watch meets the 1 ATM benchmark before being marketed as such.

3ATM/3BAR/30 M/100ft

Watches with a 3 ATM rating provide enough water resistance to cope with minor moisture exposure in daily life, such as hand washing, wearing in the rain, or accidental splashing. However, they cannot withstand immersion activities like swimming or diving. As such, the 3 ATM grade is best suited for regular everyday timepieces that may encounter some light wet conditions but are not designed for underwater use. While they can briefly handle incidental water contact like spray or droplets, prolonged submersion in water should still be avoided even for 3 ATM models to prevent leakage.

5ATM/5BAR/50 M/165ft

Watches with 5 ATM water resistance ratings can generally withstand surface swimming and snorkeling activities. However, the increased pressure of scuba diving exceeds the limits of a 5 ATM model. So while suitable for some recreational water exposure, 5 ATM watches still cannot handle intense underwater usage. In daily non-water environments, a 5 ATM watch provides protection on par with 3 ATM against splashes and rain. Some may claim 5 ATM watches can be worn safely in the shower, but prolonged exposure to hot water can degrade the sealing gaskets causing water damage over time. While better than lower ATM levels, it’s recommended to avoid bathing with 5 ATM watches and minimize any activity with forceful, high-pressure water contact.

Additionally, alloy as a watch case material typically cannot support water resistance beyond 5 bar pressure. For watches required to withstand greater water depth and pressure for underwater use, harder metals like stainless steel or tungsten steel are better suited as housing materials. The watch crystal also needs to be made from reinforced glass rather than regular acrylic crystal to handle the higher pressure. Overall, both casing construction and component choices need to match the expected water resistance rating based on the watch’s intended activity profile.

10ATM/10BAR/100 M/330ft

Watches with 10 ATM ratings can withstand the pressure at depths suitable for surface-level recreational diving and water sports. However, they are still not engineered to handle extremely deep diving conditions.

To achieve 10 bar water resistance, these watches will have at least 316L grade stainless steel casing. Additional features to reinforce water protection include screw-down crowns to lock out moisture and either full sapphire crystal or fortified mineral glass with sapphire coating as the face cover material.

The material selections and design choices enable popular water activity watches to meet the 10 ATM benchmark, while those intended for intense diving require even higher specifications.

20ATM/20BAR/200 M/660ft

Watches with 20 ATM water resistance ratings can withstand significant water pressure, making them suitable for surface swimming, high-velocity marine sports like surfing, as well as recreational and performance diving.

A 20 ATM watch designed for diving applications necessitates reinforced structural elements and materials to safely handle greater submersion depth and water pressure versus 10 ATM models. Key enhancements include screw-locked crowns and casebacks to prevent water ingress along with thickened sapphire crystal watch glasses. Readability considerations for underwater use also lead to common dial and handset lume provisions. Durable waterproof strap materials resistant to ocean conditions are also utilized, with common options being rubber, silicone or stainless steel integrated bands. Ultimately, every component choice for 20 ATM diver watches – from external construction to internal components – caters to reliable and optimal performance within deeper diving environments.

30ATM/30BAR/300 M/990ft

Watches with 30 ATM water resistance ratings are engineered to withstand extreme water pressures at very deep diving depths, making them ideally suited for professional and saturated diving applications. In addition to reinforced constructions already present in 20 ATM models, 30 ATM professional dive watches will also incorporate a helium release valve. This special valve allows helium gas molecules that enter the watch at great depths to escape back out safely during decompression, preventing internal pressure damage. Together with extraordinarily robust sealing systems, customized valves and protection mechanisms enable 30 ATM watches to reliably support the most demanding deep-sea diving operations.

Water Resistant Watch

Waterproof vs. water resistant for watches

While the terms “water resistant” and “waterproof” are often used interchangeably when marketing watches, there is an important technical difference between the two designations.

Water resistant refers to watches that have been constructed and tested to withstand water exposure up to the limits of their stated ATM ratings, whether 3 ATM, 5 ATM, 10 ATM or greater. So a 10 ATM water resistant watch has been verified to resist 10 bars of water pressure and passed ingress tests at that design depth.

In contrast, waterproof denotes watches with theoretical complete and permanent protection against any water entry at all depths. However, achieving 100% waterproofing for the entire usable lifetime of a watch is practically impossible. This same reality applies not just to watches but all products marketed as waterproof – whether phone cases, bags or other items.

While the highest ATM ratings allow watches to remain protected during extremely deep dives, material seals and gaskets will degrade over time with prolonged use. And no amount of engineering can account for unintended physical damage. So referring to watches as simply water resistant versus waterproof is a more accurate representation of real-world performance limits. Understanding these practical definitions assists buyers in setting realistic expectations when selecting watches intended for wet environments.

Water Resistance Testing Methods

So how exactly are these water resistance ratings determined?

International standards laid out by ISO 22810 dictate the procedures used to test and verify the water resistance ratings of watches. Some key aspects of the testing methodology are:

Pressure Testing:
Watches are exposed to water pressure equivalent to the desired depth rating. For example, 100m water resistance requires subjecting the watch to 10 bar of pressure. This checks if water seeps in under pressure.

Temperature Testing:
Water resistance testing is conducted across a range of temperatures – from 10°C to 30°C for most ratings, and 25-45°C for 300m+ dive watches. This ensures seals and gaskets retain water resistance despite temperature changes.

Submersion Testing
Watches have to remain watertight when submerged in water tanks for a set period based on rating. This verifies water resistance under sustained non-pressurized submersion.

Performance Testing
For dive watches rated 100m+, additional tests check operations after submersion. This includes verifying timekeeping accuracy as well as functionality of crowns/pushers.

At Romlicen, we have an in-house testing facility to evaluate water resistance of every custom OEM/ODM watch as per ISO standards. We also do additional real-world tests like pool submersion and open-water diving. Contact us to make rugged dive watches designed and thoroughly tested for underwater use.

Water Resistance Testing Machine
Water Resistance Testing Machine

Factors That Affect Water Resistance

While water resistance ratings determine how a watch performs under test conditions, there are many variables that impact real-world water resistance. These include:

Gaskets and Seals
The gaskets around the watch crystal/caseback and crown seals prevent water from entering the inner workings. However, these sealing components can degrade over time, compromising water resistance.

Case Integrity
Any deformation, cracks or openings in the watch case provide an entry point for water. This can happen if the watch face is impacted or the casing warped.

Battery Changes
When changing watch batteries, resealing needs to be done properly to maintain water tightness. Loose casebacks are a common cause of reduced water rating.

Wear and Tear
Daily use of the watch can reduce water resistance, especially if operated under water regularly. Salt deposits, accumulated dirt around seals, and simply normal aging of gaskets contribute to wear over long-term use.

At Romlicen, the watches produced for our OEM/ODM clients are engineered for water resistance suitable for the intended activity profile. We utilize watch case designs, gasket materials and sealing mechanisms tested rigorously to prevent water ingress within the rated capacity. Contact us today to make custom watches built to last!

Which Water Resistance Rating is Right For You?

We’ve covered what water resistance ratings signify and the many factors affecting real-world water protection. Now let’s talk about how to select the right water resistance for your needs.

If the watch will only be exposed to occasional splashes or light rain, 30m water resistance is adequate. These watches are not designed for underwater use.

For outdoor and swim watches, 50m water rating provides a basic level of water protection. You can swim laps and go snorkeling with a 50m watch, but cannot use it for water sports.

100m is the minimum threshold for recreational water activity watches. This covers surface swimming, snorkeling close to surface, recreational diving up to 10 meters depth. Watches with 100m rating can be used for most marine sports except scuba diving.

For scuba diving and high velocity water sports, you’ll need 200m and above rating. These deep dive watches handle sustained submersion for long periods. Some features to look for in dive watches are screw-down crowns, rotating bezels, and added tech like helium release valves.

At Romlicen, we consult with clients to determine intended water exposure levels before designing and engineering custom OEM/ODM dive watches. With our state-of-the-art facilities, each watch can be custom-tested to verify water resistance. Contact us today to create high-performance dive watches for your brand!

The Importance of Water Resistance for Custom Watch Makers

As discussed so far, water damage is one of the biggest risks for watches. Issues like foggy dials, corroded movements and leaking batteries can occur if moisture seeps in – immediately stopping the watch or reducing its reliability over time.

This is why water resistance is such a vital consideration for us as a custom watch producer. With every OEM and ODM client watch we make, our engineering begins right from the casing design and material selection to ensure water tightness for daily use.

We also pay special attention to components like gaskets and crown stem tubes, using materials like nitrile rubber, silicone and polytetrafluoroethylene to retain sealing capacity over years of use. Tight manufacturing tolerances are maintained to prevent the slightest gap in assembled watches.

Furthermore, we verify that the delivered water resistance meets the requested specs through rigorous testing to ISO standards. This gives our clients – and their customers – the confidence that the watches can withstand harsh environments.

As China’s most trusted custom watch maker, Romlicen provides reliable water resistance you can count on. If you need high quantities of affordable, waterproof watches manufactured to your specifications, contact us today for a quote!


We hope this guide has helped demystify watch water resistance ratings for you. To recap – water resistance refers to the depth to which a watch can withstand water exposure under test conditions. Factors like gaskets, case seals and overall wear-and-tear impact how it handles real-world usage.

As a custom OEM/ODM watch manufacturer catering to clients worldwide, maintaining excellent water resistance is a cornerstone of every timepiece we produce. Our engineering, material selection, and testing processes align to create highly waterproof watches suited for daily wear, swimming, or diving as per client needs.

So whether you need custom-branded fashion watches with 30m splash resistance for the looks, or 300m dive watches engineered for deep sea use – we’ve got you covered! As China’s most customer-centric watch producer, Romlicen offers a unique combination of outstanding quality, stringent testing, and immense manufacturing capacity at affordable prices.

Want to create your own wristwatch? Contact us today share your requirements – our experts are happy to guide you in selecting the right specifications for water resistance and other features!

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Picture of Romlicen - China Watch Manufacturer

Romlicen - China Watch Manufacturer

Romlicen is a leading custom watch manufacturer in China, specializing in OEM and ODM services. With expertise in crafting men's and women's watches, stainless steel timepieces, and both quartz and mechanical movements, we blend traditional craftsmanship with cutting-edge technology. Our commitment to quality and innovation makes us the preferred partner for watch brands worldwide. For custom watch solutions, contact sales@romlicenwatch.com.