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Water Resistance Explained

by Jordan Ficklin

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Depth RatingWatches are often rated as water resistant. Many years ago some watches were labeled “water proof” but this is no longer a legal practice. Instead a watch can be lableled water resistant and a pressure rating can be assigned.

Water is a powerful substance. At the depth of the Titanic shipwreck most watches would be crushed by the force of the water (as would all people not enclosed in a specially designed vessel). This is why it is important to rate them. Unfortunately the ratings can be confusing. Most watches rated at 30 meters probably wouldn’t fare too well under 30 meters of water. You really should have at least a rating of 50 meters if you plan on submerging your watch regularly. The following excerpt is from the Federation of the Swiss Watch Industry:

Water resistance is measured in bars (unit of pression, 1 bar being equivalent to 1 atmosphere), and watches are tested at these pressures for certain period of time. Exceptional pressure, as when diving, may exceed those limits, so if you are a keen diver you will need a watch that can tolerate that pounding.
Translation varies and your best guide is your supplier as it will almost certainly be part of the guaranteee.

Manufacturers often measure water resistance to a number of feet (ft), meters (m) or atmospheres (atm). Watches marked “water resistant” with or without additional indication of high pressure must comply with NIHS 92-10 watch Standard (corresponding to ISO 2281 international Standard). Such watches are designed for everyday life and must be water resistant during exercices such as short swimmings. They can be worn in different temperature and pressure conditions but are under no circumstances designed for scuba diving.

Divers’ watches must be water resistant at 330 ft minimum. They must also feature a time controller and comply with standards provided by NIHS 92-11 (ISO 6425) : luminosity, shock resistance, anti-magnetism, band solidity.

Remember that if you are going to be moutain climbing, parachuting, sky diving, hang gliding, or skiing, you will need a watch that is atm damage-protected as pressures change both above and below sea level.

For regular water use, solid metal cases or specially constructed products are recommended, including screwed-in case backs and crowns.
Do not hesitate to ask your next dealer about water resistance functions, and remember that only professional changing battery will guarantee the seals and thus the water resistance of your timepiece.

A more reasonable and easy to understand explanation follows:

  • Water resistant with no depth rating given. Ok for rain and washing hands
  • Water-resistant to 30 meters (100 feet). Will withstand splashes of water or rain but should not be worn while swimming or diving.
  • Water-tested to 50 meters (165 feet). Suitable swimming in shallow water.
  • Water-tested to 100 meters (330 feet). Suitable for swimming and snorkeling.
  • Water-tested to 150 meters (500 feet). Suitable for snorkeling.
  • Water-tested to 200 meters (660 feet). Suitable for skin diving.
  • Divers 150 meters (500 feet). Meets ISO standards and is suitable for scuba diving.
  • Divers 200 meters (660 feet). Meets ISO standards and is suitable for scuba diving.
  • Divers 1000m (3900 feet). Do what you want with it, but don’t visit the Titanic.
  • Divers 3900m (12,800 feet). Do whatever you want, including visit the Titanic.

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One Comment

  1. Prem
    Posted June 20, 2008 at 10:03 am | Permalink

    Great issue this one!
    Hi Jp, I just thought that it would be great to make a comment on this one….cheers! Prem ……. Most services/repairs should be deemed water-resistant to at least three atmospheres (ATM), which is equivalent to the pressure of water up to a depth of 30 metres. Sporty watch cases can resist moisture intrusion to a pressure of 5 or 20 ATM or higher. These are clearly marked on the outside case back of your watch.

    A wristwatch may only be designated as water-resistant if it is able to resist sweat, water drops as well as rain and does not allow any water to penetrate when held under water for 30 minutes at a depth of 1 metre. All of the watches carrying the label “water-resistant” or “water-resistant 30 m” meet these specifications.

    Since water pressure and temperatures can vary greatly while swimming or diving, such watches are not suitable for this activity even though they are water-resistant. Such watches are intended solely for normal everyday use. When pressures above 4 atmospheres (e.g. 5, 10, or 20 ATM) are indicated, wristwatches must be resistant against diving and vigorous movement in the water – in other words, a watch suitable for swimming must be tested to at least 10 ATM and thus will be water-resistant to a pressure equivalent to 100 metres.

    How long a wristwatch remains water-proof depends very much on how the watch is treated. A water-proof designation only refers to the watch at the time the test is conducted. Through aging, wear and tear, or damage, the state of the watch can change at any time. The more carefully a watch is handled, the longer it will retain its water-tight seals. Precise statements about duration are therefore not possible here. In theory, a watch can lose its water-resistance in a very short time – for example through a blow to the crown, massive impact to the case, a broken crystal, or through strong temperature changes (sauna, hot showers, cold, etc.). Every watch has maximum tolerances, and if these are exceeded, damage will occur. Watches built to a higher standard can endure greater loads, but even these have their limits. Therefore, every watch should be checked for water-resistance by a qualified professional as often as possible. The basic rule is: Water-resistance is not a permanent characteristic. At the latest, when condensation appears inside the crystal, it is time to have your watch inspected by a qualified watchmaker.

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