Originally posted by speagles2 As a consumer, if I buy a watch that is advertised as 'waterproof to 10m' I don't use it 'at my own risk' if I wear it in the swimming pool
That's an interesting analogy. As with our cameras and lenses, water resistance in watches is very often misunderstood by consumers, and might lead to arguments that manufacturers' ratings constitute misleading advertising.
Watches are generally advertised as water-
resistant rather than water-
proof (much like our cameras) because there are numerous factors that can result in water ingress. Furthermore, a watch rated for 30m water resistance shouldn't be used for swimming... it's considered resistant to accidental splashes only. You need one with at least a 50m water resistance rating (ideally, 100m plus) for swimming. Why? The rating is based on testing in a pressurised tank where the watch is completely static. When you're swimming, though, movement through the water exerts much greater pressure on the seals. Hold a 30m water-resistant watch at 1m below the surface of pool without moving it, and it might just stay dry inside (for a while, at least). Start swimming with it, and it'll let in water sooner or later.
Watches with 100m or less water resistance tend not to have screw-down crowns, and regardless of rating this is a risky choice if swimming regularly. Most people, though, don't wear their watches while swimming - just as most photographers don't use their cameras in pouring rain. Personally, I'd only swim and snorkel in a 200m (or greater) water-resistant watch with screw-down crown... but even a 200m or 300m water-resistant watch can let in water if the gaskets aren't seated just right, there's dirt or debris inside the screw-down crown, the crown or back isn't screwed down fully, the watch is worn in a hot jacuzzi, bath, shower or steam room, etc. etc.
Seiko's guidance on water-resistance states:
Quote: Please check the marking on the back of your watch case and refer to the following table to confirm
the degree of water resistance of your Seiko watch and the preferable conditions of use.
A watch’s water resistance is not permanently guaranteed. It is affected by the ageing of gaskets or deformation of watch parts due to accidental shock. To preserve a watch’s water resistance as long as possible, please follow the precautions below:
Wipe off moisture, sweat or dirt with a soft dry cloth after removing it from the wrist in order to increase the durability of the case back, gaskets and band.
After using a water resistant watch in ocean water, wash it in fresh water and dry it with a soft cloth.
Do not wash a water resistant watch while the crown is pulled out.
Do not operate the crown or press a button when the watch is wet.
A periodic overhaul service is recommended to check the water resistance of the watch regularly to ensure it’s functionality.
Even though Seiko's warranty
technically covers water damage for water-resistant watches, the highlighted areas above show there are numerous reasons ("get out clauses") why they might claim you were responsible for your lovely new watch suffering water ingress, rather than assuming or accepting it was a manufacturing fault.
So... do watch manufacturers' water resistance ratings constitute misleading advertising?