⌚ What is a watch water resistance test?
An easy-to-understand explanation of the necessity and mechanism
👉 This article is a related follow-up to ［⌚ Why does watch battery replacement take time? Reasons you can use it with peace of mind and 'things that are useful to know'］. Reading them together will deepen your understanding.
1. Basic knowledge of water resistance ratings
Watches always have a 'water resistance' rating indicated.
However, 10Bar does not mean it can dive to 10m.
Main water resistance ratings and guidelines
3Bar / 30m / 3ATM Everyday water resistance Hand washing (submerging in rain or water is NG)
5Bar / 50m / 5ATM Enhanced everyday water resistance Shower or light water work; weak against hot water and soapy water
10Bar / 100m / 10ATM High everyday water resistance Swimming/light marine sports; not for diving
20Bar / 200m / 20ATM Professional everyday water resistance Snorkeling; diving is NG, risk of water entry due to deterioration
200m DIVER’S Diver's standard diving(ISO standard cleared) Manufacturer repair is essential
※ The guidelines for 'usable scenes' are theoretical values.
👉 Depending on how water hits the watch, such as in a shower or strong running water, water may enter.
👉 Points
Bar / ATM rating = water pressure resistance in a static state
DIVER’S rating = international standard for actual diving use
20Bar and 200m DIVER’S are different! Be careful not to confuse them
2. How is the water resistance test performed?
The most common type in stores is the air pressure type.
Place the watch in a capsule
Apply the specified air pressure
Results are displayed via OK/NG lamps
👉 Right: Watch set in place
👉 There are also types that submerge the watch in water, but these are mainly used by manufacturers and specialized workshops.
3. The purpose of a water resistance test
A guideline for checking currentairtightness
A "reference value," not a "waterproof guarantee"
The reason it doesn't come with a guarantee even after testing is thatcomplete water resistance cannot be promiseddue to factors like part degradation or the use of generic gaskets
4. Should you get a water resistance test?
A water resistance test is not something you "must" do.
However, it is useful in the following cases👇
✅ People who plan to use their watch in water (sea, pool, river, etc.)
✅ Immediately after replacing the gasket
✅ When several years have passed since purchase and you want to check the current water resistance
Note that even if you don't use the watch, gaskets and parts will naturally degrade over time.
👉 It is safer to assume that performance drops due to aging rather than thinking "it's fine because I haven't used it."
Conversely, if you live a lifestyle where you rarely come into contact with water,there is no major problem with skipping the test.
In other words, a water resistance test is "something for those who need it to choose and buy peace of mind."
5. Points to note regarding water resistance
G-SHOCK water resistance
While it boasts extremely high water resistance, performance drops due to impact and degradation
Because there are many specialized gaskets,manufacturer repair is the standard
Crown (especially screw-down types)
If it is not closed properly, water will enter any waterproof watch
Even in a test, if the crown is loose, it will be judged as a fail
6. Benefits of manufacturer repair
As long as parts are available, a "water resistance guarantee" can be provided
Full-scale handling including gaskets, crowns, glass, etc.
Multiple estimates = proof that the watch's deterioration state can be accurately diagnosed
👉 Reference: ［CASIO Repair Fee Confirmation Page］
【How would I, as a watchmaker, use water resistance?】
This is a bit of a personal story, but...
With **10Bar (100m water resistance)**, you can rest easy on rainy days or days when you sweat!
However, I don't use it in situations where it gets splashed heavily or when I'm going into the water💦If you have **20Bar (200m water resistance)**, you can feel safe even if it gets wet.
However, operating the crown or buttons while it is wet is a no-go✋If it gets wet with seawater, be sure to wash it with fresh water to prevent rust and corrosion🌊
For sea fishing or outdoor activities, I sometimes use a watch that I'm prepared to accept as broken if the worst happens.
And... I love antique and vintage watches, but I'm afraid of water and humidity, so I end up choosing when I use them⌚💭
7. Summary
Water resistance labels have completely different meanings for "Bar" and "DIVER'S"
In-store water resistance tests are for checking a "guideline" using air pressure
Water resistance tests are not mandatory, but they provide peace of mind for those who plan to be in contact with water
Even if a watch is not being used, its water resistance will drop as the years go by
G-SHOCK and special gaskets are basically handled by the manufacturer
If you are looking for full-scale water resistance, manufacturer repair is the only choice
💡 I plan to cover "DIVER'S watches" in the future as well.
🔗 Related Links
Click here for a summary article organizing watch knowledge by theme.
👉 ［⌚ Watchmaker's Wisdom Summary Page］
Recommended reading to go with this article
［⌚ Is it bad to wear a watch in the bath? Explaining the reasons］
［⌚ Make a difference with daily care! How to make your watch last longer］
Thank you for reading this far ⌚✨
If you found this helpful or interesting,
please support me with a like or follow; it really encourages me!