What should I do to ensure my preowned watch remains water-resistant?

Keeping a preowned watch water-resistant depends on maintaining its seals, crown, crystal and case, then confirming their condition through professional testing. Water resistance is not permanent or the same as being waterproof. Gaskets age, lubrication can deteriorate, and an impact may compromise the case without leaving an obvious mark. A watch that was water-resistant when manufactured may therefore need inspection before it is exposed to moisture, particularly if its service history is unknown.

Start by checking the watch’s stated water-resistance rating and the manufacturer’s guidance. The rating applies to a watch in suitable condition and under controlled test conditions; it does not necessarily mean that the watch can be used at the corresponding depth or pressure. Water resistance can also be affected by movement, temperature changes and the way the watch is worn. If the rating is unclear, the documentation is missing, or the watch has not been tested recently, treat it cautiously and avoid water until it has been assessed.

Have the watch inspected and pressure-tested by a suitably qualified watch specialist. This is particularly important after a full service, battery replacement, case repair, crystal replacement or any significant knock. A pressure test can identify whether the case is holding pressure, but it should be supported by a visual inspection of the crown, case back, crystal, pushers and seals. A successful test reflects the watch’s condition at that time; it is not a permanent guarantee of future water resistance.

Ask for the seals and gaskets to be checked as part of routine servicing. These components may be located around the crystal, case back, winding crown and, where applicable, chronograph pushers. They can become flattened, brittle or damaged with age. Replacing a seal is not always enough on its own: the mating surfaces must also be clean and undamaged, and the case must be closed correctly. A specialist should use the appropriate replacement parts and confirm the result with a water-resistance test where the watch is intended for wet conditions.

Use the crown correctly whenever the watch may encounter moisture:

• Ensure a standard crown is pushed fully home and screwed down if the design includes a screw-down crown.
• Do not pull out, turn or press the crown or chronograph pushers while the watch is wet or underwater.
• Check that the crown is not partially open before washing your hands, entering water or going outdoors in heavy rain.
• If the crown feels loose, fails to engage properly or shows unusual resistance, stop using the watch around water and arrange an inspection.

Keep the watch away from sudden changes in temperature. Hot showers, saunas and heated pools can increase pressure inside the case and may cause seals to expand or contract. Cold water followed by heat can also encourage condensation. Steam is particularly problematic because it can penetrate areas that may resist occasional splashes. Water resistance should not be assumed simply because a watch is described as suitable for swimming.

Rinse and dry the watch appropriately after contact with salt water, chlorinated water, soap or cleaning products. These substances can damage finishes and accelerate deterioration of seals. Use clean fresh water only where the watch’s condition and rating make this appropriate, then dry it with a soft, lint-free cloth. Do not use a hairdryer, radiator or other direct heat source. If the watch is not known to be water-resistant, wipe away moisture rather than rinsing it.

Take extra care after an impact. A knock against a door frame, desk or sports equipment can affect the crystal, case back or crown even when there is no visible damage. Look for chips, cracks, gaps, a loose crown or moisture beneath the crystal. If condensation appears inside the crystal, remove the watch from your wrist, do not operate the crown, and arrange professional attention promptly. Leaving moisture inside the case can damage the movement and dial.

Vintage and heavily worn preowned watches require particular caution. Previous polishing, replacement parts, corrosion, worn threads or an altered case can affect how well the case seals. A watch may retain its original water-resistance marking but no longer be suitable for the same use. Do not rely solely on age, appearance or a previous owner’s assurances; ask for its current condition to be assessed.

A practical care routine is to:

1. Confirm the watch’s water-resistance specification and any restrictions in its documentation.
2. Check the crown, crystal and case for visible damage before exposing the watch to moisture.
3. Keep the crown secured and never operate controls underwater.
4. Arrange a pressure test after servicing, repair or a significant impact.
5. Have seals inspected during servicing and replaced when their condition requires it.
6. Avoid showers, steam rooms, hot tubs and chemical exposure unless the watch is specifically designed and confirmed for that use.

If you are uncertain whether your preowned watch remains water-resistant, the safest approach is to keep it dry until it has been examined and tested. This is especially important where the watch has an unknown service history, has recently been opened, or shows any sign of impact or condensation.