Have you ever seen the words ‘Water Resistant’ or something like 50M/100M on the back of your watch? Although they seem simple, they can help give you an indication of how waterproof your watch is.
Water resistance is one of the most important factors to consider when buying a new watch. If you wear your watch daily, often swim or simply want a watch that can resist water from rain and splashes then this can help you find the right watch for your needs and help you take care of it.
In this quick guide we will tell you everything you need to know about water resistance. We will tell you what it means, how the different ratings work, what ATM and Bar means and how to keep your watch safe.
What Does Water Resistance Mean?
Water resistance means the watch is able to resist water getting into the internal parts of the watch.
Inside the watch there are many delicate parts including the movement, dial, hands etc. If water gets into the case, it can cause issues such as condensation, corrosion, rust and damage.
Manufacturers will include water resistant features such as rubber seals, gaskets and special cases. The crown and case back must also be secured.
However, this does not mean that your watch is 100% waterproof. You may find that your watch is not suitable for diving or high pressure water, even if it is resistant to splashes or swimming.
It will depend on how the manufacturer states your watch is rated, how it is built and its condition.
Understanding Water Resistance
Water resistance on watches is often shown using metres (M), atmospheres (ATM) or bar. This shows how much pressure your watch can resist.
General guide:
| Water Resistance Rating | Typical Use |
|---|---|
| 3 ATM / 30M | Everyday wear and light splashes |
| 5 ATM / 50M | Everyday use, rain, and some swimming if approved by the manufacturer |
| 10 ATM / 100M | Swimming and many recreational water activities |
| 20 ATM / 200M | More demanding water activities and some diving applications |
| 30 ATM / 300M or higher | Certain demanding diving activities, depending on the watch's design and certification |
Note: These are general guidelines. Always check the manufacturer's instructions before exposing your watch to water.
1. 30M or 3 ATM
If your watch is rated to 30 metres then it is generally intended to be worn on a daily basis. It could be suitable for hand washing but generally should not be used for swimming or showering.
There can be confusion with the 30M rating as it does not mean it can be used at 30 metres.
2. 50M or 5 ATM
A 50M or 5 ATM watch will offer more protection than a 30M watch. It can often be worn on a daily basis, in the rain and for certain swimming activities (With manufacturers approval). Not all 50M watches will be suitable for swimming. It will depend on how it is built, its condition and what the manufacturer recommends.
If you often swim then check the official specs.
3. 100M or 10 ATM
A watch rated to 100M or 10 ATM will generally be a more practical choice if you enjoy swimming and recreational water activities. Depending on how it is built and the manufacturers instructions it could be suitable for swimming, snorkelling and other activities.
However, this does not mean that your watch will be suitable for scuba diving. Look for a watch that is specifically designed and rated for diving.
4. 200M or 20 ATM
A watch rated to 200M or 20 ATM will offer more protection. Some are specifically designed for recreational SCUBA diving and intense water activities. If you plan on diving with your watch make sure it meets the correct standards for diving watches and the manufacturer approves it.
Although it is great to have a higher rating, it is important that it is well built.
5. 300M or Above
Watches rated to 300M or above are often specifically designed for intense water activities. They can be used for intense diving activities. Some professional diving watches will have extra features such as a rotating bezel, strong case and easy to read.
However, make sure you follow the manufacturers guidance. Always check what your watch is specifically rated for.
What Does ATM and Bar Mean?
ATM and Bar are units of pressure.
One atmosphere is roughly the same as 1 bar. Therefore they are often used interchangeably.
Examples:
- 3 ATM = Roughly 3 Bar
- 5 ATM = Roughly 5 Bar
- 10 ATM = Roughly 10 Bar
- 20 ATM = Roughly 20 Bar
Water resistance can be affected by many factors such as movement, sudden shocks, temperature changes and the condition of seals.
Why Can’t I Use My 100M Watch for Diving?
This is one of the most common misconceptions.
When a manufacturer states their watch is water resistant to 100 metres, it is generally referring to pressure resistance. It does not necessarily mean that it can be used at 100 metres.
Activities can cause extra issues. Moving your arm in water, jumping in the pool and pressure changes can put extra stress on your watch. Your watch will also depend on the condition of the seals.
Therefore a watch rated to 100M may not be suitable for deep diving. It may only be suitable for swimming or certain recreational activities.
Always choose a watch that is approved by the manufacturer for the activities you want to do.
What Makes a Watch Waterproof?
There are several factors that help keep your watch waterproof.
Rubber Seals and Gaskets
Seals are small parts that surround areas such as the case back, crystal and crown. This helps keep water out.
Over time the seals can get damaged. This can be caused by age, heat, chemicals and general wear and tear. If your seals are damaged or hardened then your watch won’t be as water resistant.
Case
The case of the watch protects the internal mechanism. Watches that are more water resistant may have extra reinforcement, specialised closures and pressure resistance.
Crown
The crown is used to set the time and sometimes date. As this opens up the case, it is important that this part is kept water resistant.
Some watches have screw in crowns to help keep the crown secure. However, it is important to make sure it is secured before exposing it to water.
Never move the crown or pushers whilst underwater unless the manufacturer approves.
Crystal and Case Back
The crystal and case back must be kept sealed. If they are damaged then your watch won’t be as water resistant.
If your crystal is damaged, case back is loose or the seals aren’t well maintained then your watch may not be as water resistant.
Should I Wear My Water Resistant Watch in the Shower?
Even if your watch is quite water resistant it isn’t always a good idea to wear it in the shower. Hot water, steam, soap, shampoo and other products can cause issues with the seals. The crown and case may also get a build up of residue. Temperature changes can also cause extra stress on the seals.
As a general rule it is best to take your watch off. Unless the manufacturer specifically approves it. The same applies to hot tubs and saunas. Just because your watch has a high water resistance rating doesn’t mean it can be used in hot water or steam.
Does Water Resistance Get Worse Over Time?
Yes! Your watch can lose water resistance over time.
The gaskets can become brittle, seals can become damaged and the case and crystal can become damaged from accidental knocks. Your watch may no longer be as water resistant as it was when new. Opening up the case to change the battery can also affect water resistance if the seals aren’t checked and put back correctly.
If your watch is often used for swimming or diving then follow the maintenance advice given by the manufacturer. A qualified watch technician can check the seals and carry out a water resistance test.
Don’t assume your watch is water resistant just because it is old.
How to Keep Your Watch Safe From Water Damage
Here are some top tips to help keep your watch water resistant.
- Check the rating – Make sure you know if your watch is for splashes, swimming or diving.
- Secure the crown – Ensure that the crown is fully pushed in or screwed in.
- Don’t move any controls – Don’t move the crown or buttons whilst underwater unless the manufacturer approves.
- Avoid extreme heat – Avoid hot tubs, saunas and temperature changes unless the manufacturer approves.
- Rinse – If the manufacturer approves swimming then rinse your watch in fresh water after using it in chlorinated/salty water. Wipe dry with a soft cloth.
- Check for damage – Check for any cracks, damaged crown, loose case back or signs of wear.
- Professional test – Have your watch professionally tested for water resistance after servicing or if you often use it in water.
Simple habits can help keep your watch safe from water.
What Should I Do If Water Has Got Into My Watch?
If you see condensation under the crystal or water inside your watch then take it seriously. The water can cause damage to the movement and cause corrosion.
Stop using your watch in water and have it checked by a professional. Don’t use a hairdryer, put it on a heater or try to open the case. If it is under warranty then check the manufacturers service instructions.
Getting it checked early can help stop any further damage.
FAQs
Is a 30M watch suitable for swimming?
A watch rated to 30M is generally intended for everyday use and splashes. Check the manufacturers instructions.
Can I swim with my 50M watch?
Some 50M watches are approved for swimming but others may have stricter guidelines. Check the manufacturers recommendations.
Is a 100M watch waterproof?
No watch should be assumed to be completely waterproof. A 100M rating means it can resist a certain amount of pressure.
What Does 10 ATM Mean?
This means it can resist 10 atmospheres of pressure. Many watches will have a nominal 100M rating. However, it will depend on the model.
How Often Should I Have My Watch Tested for Water Resistance?
Follow the manufacturers maintenance advice. If you often swim/dive with your watch it is important to have it tested periodically. It is also a good idea to have it tested after servicing, a big knock or if you suspect the seals have been damaged.
Are All Diving Watches 200M?
No! Diving watches can have various ratings and certifications. Check the specific model.
Conclusion
Water resistance is an important feature to help keep your watch safe from water. However it is important to know the limitations. 30M, 50M, 100M and 200M ratings show how much pressure your watch can resist.
If you are wearing it for everyday use then a basic rating may be enough. If you often swim then look for a watch that is specifically approved by the manufacturer. If you are going SCUBA diving then look for a diving watch that has been specifically designed and has the correct rating.
Most importantly keep in mind that water resistance can get worse over time. Taking care of your watch, keeping it checked and having it tested by professionals can help keep it safe and prolong its lifespan.
Next time you are buying a new watch check how water resistant it is. Make sure it fits with your lifestyle. A little knowledge can go a long way!
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