Misinformation abound in this thread OP, the Apple Watch uses gaskets and strong adhesives to keep out water so these may dry out and lose effectiveness after a time. What time? I don't think my one except maybe Apple fro, running long term tests.
In practical use and time I'd wager you should be fine. But in ten years I shouldn't try to go down to 50 meters to test it kind of thing, may be fine may not be.
Apple page on water resistance
Water resistance isn't a permanent condition and may diminish over time. Apple Watch can't be rechecked or resealed for water resistance. The following may affect the water resistance of your Apple Watch and should be avoided: * Dropping Apple Watch or subjecting it to other impacts. * Exposing Apple Watch to soap or soapy water. * Exposing Apple Watch to perfume, solvents, detergent, acids or acidic foods, insect repellent, lotions, sunscreen, oil, or hair dye. * Exposing Apple Watch to high velocity water, for example while water skiing. * Wearing Apple Watch in the sauna or steam room.