Value Village ／ Clothing
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How to read the water-resistance marking on a wristwatch is one of the most misunderstood topics on Q&A sites in every country. Japan has its own industrial standard (JIS) that defines the water-resistance classes, and what "◯-bar water resistant" means is set out there. If you bought a watch in Japan, this is the system the label follows.
| Marking | Intended use | Avoid |
|---|---|---|
| Water resistant for daily life (3 bar / 30 m) | Hand-washing, rain | Swimming, bathing, washing the car |
| Enhanced water resistance for daily life (5 bar) | Wet work, shallow swimming | Diving in, underwater swimming |
| Enhanced water resistance for daily life (10–20 bar) | Swimming, skin-diving | Scuba diving |
| Diver's watch | Scuba diving | Diving deeper than the marked depth |
"30 m water resistant" does not mean you can dive to 30 m. It is the value from a static pressure test; when you move your arm, the local pressure exceeds it.
[Verify] Check the classes and their intended uses against the Japan Clock & Watch Association's "About water resistance in watches" and the text of JIS B7021.
Changes in temperature make the gaskets expand and contract, and steam or soap can get inside. Many makers advise against wearing a watch while bathing or in a sauna.
What keeps water out is a rubber gasket, and rubber degrades with age. The usual advice is to have it replaced at battery changes or at a check-up every 2–3 years.
Heat harms the inside of the watch. The basic rule: wipe with a dry, soft cloth, and if you see moisture inside the glass, take it to a watch shop promptly.
Magnets in everyday objects are on the increase: smartphone and tablet covers, magnetic bag clasps, headphones. Both mechanical and quartz watches are affected, and magnetism can make them gain, lose or stop. The Japan Clock & Watch Association advises keeping watches at least 5 cm from magnetic products.
The salt in sweat causes rust and can cause metal allergy. Wiping the case back and strap with a dry cloth when you get home is a habit shared among people living in Japan.
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https://www.jcwa.or.jp/etc/waterproof.html
https://www.jcwa.or.jp/etc/magnetism.html
https://www.jisc.go.jp/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
Follow the care label and the maker's instructions for any garment, shoe or bag. For expensive or sentimental items, ask a specialist cleaner or repairer.
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