Short answer
No. A long soak in hot water is one of the worst things you can do to a watch, even one rated 100 m. Heat softens the rubber gaskets that keep water out, soap breaks down the oils around them, and steam slips past seals that handle cold water just fine. If you want the thing to last, take it off before you get in.
What water resistance ratings actually mean
Numbers like 3 ATM, 5 ATM, and 10 ATM get thrown around like a license to swim. They are not. The label describes a lab test under narrow conditions: still, room temperature water, brief immersion, no soap, no steam. ISO 22810 is the standard behind most of those ratings, and it says nothing about a 40 minute soak with bath salts and a hot shower running nearby.
- 3 ATM: splash resistant. Rain, hand washing. Not for baths.
- 5 ATM: a quick cool shower is the realistic limit. Still not built for hot water or soap.
- 10 ATM: pool swimming is reasonable. A long hot bath is not.
- 20 ATM and up: dive rated, made for cold water under pressure, not for a jacuzzi.
Why hot water is the real problem
Seals are the whole game. A watch is a metal box with rubber rings at every opening: the caseback, the crown, the crystal edge, the pushers. Those rings are rated for a temperature range, and bath water sits at the top of it or past it. Warm water makes rubber expand and soften, and when it cools, the seal does not always return to the exact shape it started in. Do that twice a week for a year and you have a slow leak.
Soap makes it worse. Shampoo, body wash, and bath oil lower surface tension, so water creeps into gaps it would normally bead off. Residue also dries on the gasket and can make it stick, which is how a crown stops sealing the way it should.
Steam is a separate enemy
Steam molecules are smaller than liquid water and move faster. A hot bath fills a bathroom with vapor, and vapor gets through seals that liquid cannot. It condenses inside the case, right where the movement lives. Fog under the crystal after a bath is the classic warning sign.
If you own first copy watches, read this part
Water resistance claims on first copy watches deserve extra skepticism. A genuine rating comes from a tested sample and a warranty standing behind it. Copies often carry the same numbers on the dial or caseback without the same gasket quality, torque specs, or caseback sealing. A copy marked 10 ATM may have never seen a pressure test at all. I treat any copy watch as splash resistant at best, and I do not wear one in the bath, the shower, or the pool, no matter what the back of the case says.
What about a quick rinse after a bath?
A cool water rinse with the crown screwed down is fine for most watches. Wipe it dry with a soft cloth instead of letting it air dry, since minerals in tap water leave spots on the case and crystal. Skip the rinse if the watch is vintage or has not been serviced in years.
If your watch does fog up
- Take it off and stop fiddling with the crown. Do not shake it.
- Wipe the outside dry.
- Keep the crown closed and get it to a watchmaker. Moisture inside causes rust on steel parts fast.
Opening the case yourself to dry it out usually makes things worse, since you cannot reseal it properly without fresh gaskets.
Bottom line
A long bath and a watch are a bad pair. Take it off, set it on a dry surface away from the steam, and put it back on when you are dry. That one habit does more for a watch's lifespan than any number printed on the caseback.