The numbers on a caseback are easy to misread. “30 m” does not mean you can dive to 30 metres. Here is what Seiko’s markings really allow, straight from the Seiko manual.
What the markings mean
| Marking on the watch | What Seiko says it is for | Swimming? |
|---|---|---|
| No marking | Non-water resistant. Avoid drops of water and sweat. | No |
| WATER RESISTANT | Accidental contact with water in daily life | No |
| WATER RESISTANT 5 BAR | Sports such as swimming | Yes |
| WATER RESISTANT 10 or 20 BAR | Diving without an air cylinder | Yes |
| DIVER’S 200m (and similar) | Diving watches built for scuba use | Yes |
Rules that keep water out
- Never use the crown or pushers underwater. Seiko says this in its diving precautions.
- Screw the crown fully down before you get wet.
- After seawater, soak the watch in a bowl of fresh water and dry it. Seiko advises against holding it under a running tap.
- Leather straps are not for water, even on a water-resistant watch. Seiko says so in its band care notes.
- Gaskets age. Seiko recommends an overhaul every 2 to 3 years, including new gaskets.
Vintage Seikos are different
A 1970s diver rated 150 m was rated when new. After 40 or 50 years, gaskets have hardened and crowns may be aftermarket. Treat any vintage watch as not water resistant until a watchmaker has pressure-tested it. If water has already got in, see what to do about condensation.
Frequently asked questions
Is ‘Water Resistant’ on a Seiko OK for swimming?
No. Seiko says a watch marked only WATER RESISTANT handles accidental contact with water in daily life, and should not be used for swimming.
Which Seiko is safe for swimming?
Seiko says a watch marked WATER RESISTANT 5 BAR is suitable for sports such as swimming. 10 or 20 BAR is suitable for diving without an air tank, and DIVER’S watches are built for scuba.
Should I rinse my watch after the sea?
Yes. Seiko says to rinse it in fresh water after seawater and dry it carefully, and to soak it in a bowl rather than hold it under a running tap.
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