As a child, there was one feature you really wanted from the very first watch you came to own. It wasn't a date display and it wasn't interchangeable straps - though both were considered very cool; It was water resistance. Even though you were unlikely to go deeper than the bottom of a hot bath or a local swimming pool, for some peculiar reason water resistance mattered. It made your watch cool.
Now we're all grown up, water resistance still matters, but it's not quite as simple to understand as people initially think. That's why we've put together this guide to water resistance in watches, as part of our Know Your Watch series.
The real meaning of "water resistant"
It's important to realise that "water resistant" or "waterproof" doesn't mean what you think it does. When you see "water resistant" written in a wristwatch's description, but there is no additional detail given, i.e. a distance measurement in ATM or metres, more often than not this means that the watch has been made to not let water in when it is splashed near or onto the watch, but it definitely does not mean that the watch should be submerged under water. In other words, most watches are designed to withstand minimal, accidental contact with water through activities like washing your hands and perspiration.
The watches that are built to be worn metres under water are designed not only with a resistance to water in mind but also with careful consideration to the pressure that being under water brings, as this is what truly effects a watch's "water resistance", as explained below.
How a watch's water resistance is measured
If you require a watch to stand up to being submerged in water to a certain depth you need to learn about how water resistance is measured so you know that your watch is up to the pressure of being under water. While some watches will refer to water resistance up to a certain distance - i.e. 10 metres, 100 feet - the correct way to measure water resistance under water is in atmospheres, which are abbreviated to ATMs. You may have already come across this if you've ever tried scuba diving as it's the same terminology. 1 ATM refers to a depth of 10 metres underwater, 3 ATM is 30 metres under water and so on. It's also worth noting that you may hear "ATM" referred to as "bar", so watches with 5 ATM can also be listed as having a "5 bar" resistance.
When watches are tested at certain depths they are held underwater in a stationary position. It follows that if the watch is then worn by someone who is moving around a lot, the pressure on the watch then increases according to how fast the watch is moving. In other words, the biggest threat to watch isn't so much the water but the pressure that being under water can apply to your watch.
If you want to go deep...
That said, understanding how deep you can go with your watch is not necessarily as literal or clean cut as you would imagine, i.e. do not assume that a watch with 3 ATM is up to surviving a deep sea dive of 30 metres because it's not. In fact, even a watch with 1 ATM should not actually be worn submerged in water for an extended period of time. As a general rule even a 3 ATM watch is still not suitable to be worn in a shower and you'd need a minimum of 10 ATM resistance to keep your watch on while swimming.
Most watches that have 3 ATM water resistance are built to resist accidental water damage and spillage, but they should be removed before intentional submersion or contact with water. If you want a watch for deep water activities like diving, your best bet is to buy a specialist watch that has a minimum of 20 ATM. If you're looking for a watch that you can forget about when you shower or take part in a wide range of sporting activities, including swimming, you're best bet is to get a watch with a minimum of 10 ATM. Most watches at Twisted Time have a water resistance of 3 ATM and below are a selection of watches with 5 and 10 ATM currently in stock at Twisted Time.