What's the real deal with watch water resistance?

If you're sufficiently interested in watches to be reading this you probably know that a watch which is rated as, say, 5 ATM/5 bar/50m is based on 'static pressure' tests and that it categorically is NOT guaranteed to survive being worn to that depth under water.

I've tried looking into this and finding empirical evidence of what watch water resistance ratings mean in real world scenarios but it's a fools errand and so I defer to the wisdom of the WC community: what's the truth about water resistance and watches?

Here's my take based on reading/advice I've gleaned over the years (based on the assumption that everything under 10 ATM/10 bar/100m does NOT have a screw-down crown:

WR: 30m (and under) = Don't even think about getting it wet. Seriously. Take it off before you wash your hands. Check the weather and take it off if rain is scheduled. Don't be sweating near this thing. In the box, back of the safe, that's about it.

WR: 50m = Probably OK to wash your hands but don't go immersing it in water. No dish washing, don't shower in it and don't even consider swimming.

WR: 100m (but no screw-down crown) = You're good to go. Not swimming, obviously, but everyday type stuff. You might even consider showering with it on (quickly) if you're not too attached to it.

WR: 100m (with screw-down crown) = Now you're talking. Swim your heart out. I wouldn't dive with it or anything, but jump in the hotel pool? Sure.

WR: 150m = Yeah, OK, you can probably dive with this thing but I'd top out at freediving and don't come crying to me if you neglect to screw down the crown or whatever. Get a dive computer, why don't you?

WR: 200m+ = Congratulations, you have a genuinely waterproof watch. Stay out of the Mariana Trench and everything should be copacetic.

Is this fair/accurate? Any stories from users proving/refuting this? Should we as buyers be demanding 'accurate' WR ratings from watch manufacturers that reflect how deep you can swim and/or something else to put the wearer at ease? I know I'd like a spec sheet that offers a binary 'can be immersed'/'can't be immersed' indicator so I know where I stand when taking a watch to the pool or on holiday.

Don't know about you, but an 'honest' 10m water resistance would cover me for absolutely anything I would ever consider doing outside of falling drunkenly over the rail of a luxury cruise ship.

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Well, there are a few inaccuracies in this and complications that make this sort of a general policy highly difficult to implement properly.

For instance in almost all cases a screw-down crown makes no difference to the water resistance whatsoever. It does help to prevent the user from accidentally pulling the crown while swimming, but if you don't do that, the type of crown makes no difference, so I don't see how a screw-down crown would be a requirement for swimming in general.

As for the other stuff, it's just annoyingly complicated. The water resistance ratings are fairly arbitrary and can change between watches. For example a lot of brands treat 100m as a minimum, for swimming, but Casio tells you that their 50m rated watches are perfectly fine for swimming and they aren't known to fail at this from what I have seen.

If you want something that you can trust to be water resistant, get something with a Diver's rating, which means that they genuinely have to be good enough to pass the relevant ISO standard and the company can't just apply arbitrary criteria.

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Excuse my naivety, but surely a screw-in crown would be less likely to fail apposed to a push in?

Just as a rule of thumb (and being a plumber) I would never swim with a watch without having a screw-crown,

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Rodiow

Excuse my naivety, but surely a screw-in crown would be less likely to fail apposed to a push in?

Just as a rule of thumb (and being a plumber) I would never swim with a watch without having a screw-crown,

Interesting if true that the screw down crown is not the last word in water resistance. Anyone have a take on how much the SDC is psychologically reassuring rather than practical??

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Anyone else remember those huge Russian deep sea dive watches with a massive canteen screw on crown?, surely that's not just for looks?

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WR rating is meaningless, Try to redeem a warranty for a flooded watch if you don't believe me.

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The WR rating on the dial is more or less a number. You can inspect the gaskets of the watch if you are so inclined. After having done so, and found that they are in good condition, in the right place, and free of dust, hair, etc. , you can have a reasonable expectations of water resistance. On the other hand I have seen watches where the person changing the battery in his little stall at the mall completely forgot the gasket.

While there is some reasonable expectation that a new watch is water resistant, the only way you know for sure is if you pressure test the watch.

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It’s a conspiracy

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DixonSteele

Interesting if true that the screw down crown is not the last word in water resistance. Anyone have a take on how much the SDC is psychologically reassuring rather than practical??

I’ve also read a bunch on this and the crow type doesn’t change the effectiveness of the water rating, it’s just an added security measure to prevent the crown for popping out while submerged. 100m WR = 100m of WR, regardless if crown type. The SDC just adds more peace of mind.

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Very interesting regarding your Citizen. No way I would have the guts to risk the Santos, personally. For my money it feels like I need a watch to be 100m, SDC and probably under £1500 for me to feel comfortable submerging it.

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Since I assume that if my Dive watches were to take on water regardless of what is promised in the specs my warranty would be meaningless, I therefore have one less expensive Dive watch that I wear to the beach as well as to the pool. Given the price, it has never been a risk I’m willing to take.

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BigIona

I’ve also read a bunch on this and the crow type doesn’t change the effectiveness of the water rating, it’s just an added security measure to prevent the crown for popping out while submerged. 100m WR = 100m of WR, regardless if crown type. The SDC just adds more peace of mind.

Thanks for this. Thinking about the psychological nature of this I think the way the watch is sold also plays into how comfortable I am with it around water. My Longines Sprirt 37mm is rated to 100m with no screw-down crown so, based on the above, should be fine... But I bought it on a leather strap. So now, in my head, it's a leather strap watch, not a watch that's suitable in water. First impressions and all that, I guess...

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Rodiow

Excuse my naivety, but surely a screw-in crown would be less likely to fail apposed to a push in?

Just as a rule of thumb (and being a plumber) I would never swim with a watch without having a screw-crown,

The fact is that my 200m Casio do not have a screw in crown, just as some other 200m och 300m watches I read reviews about and IF it actually is needed (or even better) for 100m, should it be even more needed for 200m watches!

And if a watch is rated for 100m, should the crown naturally handle 100m whatever way the crown work and it may also be SAFER with a crown, you simply can't forget to screw down!

Then depend the swim and shower recommendations on a completely different factor...

Every watch is rated for normal "medium hard" water and sweat, skin grease, soap, shampoo and any dish washer stuff, make the water little to a lot more "softer" and that help it penetrate... So 100m become actually like 10m when you swim and possibly only like 1m when you shower or do the dishes!

But I take anyhow off my watch - when I shower or worse, because the cleaning stuff may also damage the sealing in the watch... Except my digital Casio 100m, that stay on when I clean the boat and still live...

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My non scientific rule of thumb is if its 200m I swim in the pool, sea and snorkel with it. Anything below that I don't swim with it.

I used to do a fair but of recreational diving and only wore a dive computer.

My recent big purchase was a pelagos with 500m and an escape valve. Totally over engineered for my uses but it gives me a warm feeling!!

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BigIona

I’ve also read a bunch on this and the crow type doesn’t change the effectiveness of the water rating, it’s just an added security measure to prevent the crown for popping out while submerged. 100m WR = 100m of WR, regardless if crown type. The SDC just adds more peace of mind.

The SDC just adds more peace of mind.

While technically true, I would consider this a bit of an understatement, as any movement of the push-down crown, even inadvertently, could otherwise break the seal. That being said, something that might be overlooked and harder to visually inspect is how well the crown tube seals against the case.

Even this test would tell you something about obvious deficiencies.

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But seriously, if I was to go swimming with a watch of any relevant value, I would have it tested.

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Rodiow

Excuse my naivety, but surely a screw-in crown would be less likely to fail apposed to a push in?

Just as a rule of thumb (and being a plumber) I would never swim with a watch without having a screw-crown,

From the possibility of hitting the crown on something, yes.

From purely water, no. The threading isn't water resistant and the gasket is the exact same as what you would find with a push-pull crown.

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I swam with a 30m Seiko 5 watch. Repeatedly. Even did jumping off a bridge with it all summer. No issues ever.

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I’m just gonna go based on the manufacturer suggestion. I’m a go swim with my FC highlife lol

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If the watch has a water resistance rating, then I wear it while swimming showering, hand-washing, everything.

I swim with my Speedmaster Moonwatch and Hamilton Khaki Field Mechanical (both rated at 50m) and have never had any issues. I don’t think my digital watches as a kid had anything more than a “water resist” pledge on them, and I would jump into any body of water I could find without ever worrying about my watch!

These things are metal tools. Stop being afraid of them. You bought them to wear, so wear them!

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This guy pressure tested (among others, check it out) a couple of dive watches, a Citizen rated at 100m and a Dugena rated at 300m:

https://www.youtube.com/watch?v=Ti-GdfGbj4Y

Of course these are just two specific manufacturers, and perhaps it's anecdotal, but it seems to suggest that at least some manufacturers conservatively rate their watches WR. The Citizen far exceeded its rating and finally stopped running at 280m (it restarted once the pressure was reduced) and didn't catastrophically explode until 2070m. And the 300m-rated Dugena finally stopped running at 1km! Yes, one kilometer of pressure!

On a personal level it's NBD for me, since my watches are easily replaceable. I go into the ocean and swim with an early 2000's, unremarkable RELIC quartz with a push-pull crown and rated at a meager 50m and it laughs when we emerge from the waves. I rinse it in the sink when we get back to the house, dry it and put it away for the next time. It's my beach buddy. My 200m Invicta Pro Diver is on deck, followed by a 300m Grand Diver. I will report back if they disappoint. Honestly.

If you're really concerned about diving WR, quit dicking around and just do what @ottop1 said and get something ISO rated. Otherwise you "rolls the dice and takes your chances," as they say.

Or if you have a Rolex Sub, I'd bet on those laughing after a dive, given their kick-ass toughness rep. But that's just me.

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I won't wear a watch in the water I'm afraid to damage or lose... nuff said there.

Showering makes steam, steam is bad m'kay?

Ok I'm done 👍

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Only my personal rule :

I don't shower with my watches, never. Except my G shock. Steam is a b***h.

3atm ok to wash hands, but take off for dish washing

5atm same but eventually I can keep it if dish washing is a short one

10atm and more I do everything with it, taking bath, swimming, beach, running in the snow...

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Have never worried much about shower steam. I likely have the water too cold to worry about anyway. I’m a wimp like that.

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salgud

This is a commonly accepted and oft-repeated myth in the watch world. It is simply not true. As a Metallurgical Engineer (retired) who has designed, constructed, tested and operated thousands of pumping/piping systems, I can say that the speed at which a person can move their hand through water has an infinitesimal effect on WR. This can be easily calculated using Bernoulli's Theorem. It has no bearing on a watch's WR.

Same thing with your comment regarding water coming out of a tap "under pressure". That proves wrong because as soon as water comes out of the tap, it is now under only atmospheric pressure, the same as a puddle on the road. No effect on WR.

I've asked everyone who makes this statement to show me proof using science. That would be Bernoulli's Theorem. No one has ever even bothered to reply because the only proof they have is that some other would-be scientist has made the same specious claim.

Let's just kill this myth off!

Well, you learn something new every day!

According to Stoke's Law, moving just over a foot per second under water would apply five pounds of pressure to your watch face. Here's the math:

F = 6πηrv

where F is the drag force, η is the viscosity of the fluid, r is the radius of the object (or half the width of the hand), and v is the velocity of the object through the fluid.

To experience 5 pounds of resistance, we need to solve for v:

5 lbs = 6π(0.01 Pa·s)(0.5 in)v

Simplifying the equation, we get:

v = 5 lbs / [6π(0.01 Pa·s)(0.5 in)]

v ≈ 13.23 inches per second

Apparently being under 100 meters of water is about 145 pounds of pressure? I guess I never thought about it that way. Five more pounds definitely isn't double that.

Thanks for opening my eyes.

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The age old debate. How much water resistance do I need for my desk diving endeavors? I am as guilty as everyone else and wouldn't think of desk diving with anything less than 200m even though actual diving below the 40m certification level for recreational divers would require you to account for decompression stops (but hell, I have a hesalite Speedy just in case NASA calls so maybe I need a deep sea or helium escape valved watch too, just in case).

Because you can't tell what the different brands mean (or are marketing) with their stated water resistance ratings, it is probably safest to check with the brands themselves. Here is the link to what Seiko says about water resistance ratings on its watches (basically 5 bar/ 50m ok for "swimming",  10-20 bar/ 100-200m ok for "shallow diving",  divers 200 ok for "scuba diving", and professional divers 1000 ok for "saturation diving"): https://www.seikowatches.com/us-en/customerservice/faq/general-information-8

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This is making me think that 50m is talking about pool length and not pool depth? 🧐

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Collectors go crazy over details. I get it. When I collected comics, print editions and creases were the bane of my existence. They have to not have a single crease, must be 1st printing.

With watches, I decided I’m not gonna go nuts over details. Does it look good? Okay, buying it. Only 100m WR? Does it look good? Okay, buying it. Only 30m? Does it look good? I just don’t want to worry about it too much. My Loreo has 200m? Good. Will use that for ALL the water activities. My Seamaster has 300m? Okay, won’t use that for any water activities. Just because the consequence of something happening to the Omega outweghs any potential fun I could have with it in water.

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Before I was 'into' watches I used to wear my watches for everything from high-impact activities to hot showers, saunas, spas, swimming. No issues with any of these even with a 30m Skagen, Fossil chrono (again 30m). I was blissfully unaware that 30m meant anything other then I could do anything up to and including going 30m deep underwater!

I now primarily wear my SMP 300, but dont shower in it, although I do rinse it under the tap daily just to keep the grime buildup down. I wouldnt hesistate to wear it in any water-based activity other than a steamy shower, and thats only because I want to clean my wrists properly!

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I feel like I won't add anything to the conversation, or even add something that I haven't already said, but, I think people baby their watches far too much when it comes to water resistance.

I personally have gone diving hundreds of times with a simple digital 100m casio, and even used the buttons while underwater, and it's still going strong (it's just a little less accurate after 10 years of ownership). And my parents have gone diving also hundreds of times with a little 200m quartz diver with a push-pull crown, and it hasn't taken in water in the 30 years they've owned them. I will also take anything that has 100m written in the specs swimming, including my pagani design daytona, and none of my 50m watches are on a strap that would survive water so I haven't tried getting those wet. The only watch that I've ever had take on water was a 25 years old certina with a push-down caseback that took a full blast of water from a shower head, I just popped it open, drained the water and let it breathe open for a day and it was fine, didn't even stop or lose accuracy.

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With or without a screw down crown, if you have a concern pay to have your watch pressure tested (wet) by a watchmaker. 🤙🏼