Myths about water resistance: What watches can really withstand

To be labelled “waterproof”, a watch must meet high requirements. It must withstand a pressure of 2 bar for 10 minutes. This is the pressure that exists at a depth of 20 metres. It must also not allow any moisture to enter the watch for an hour at a depth of 10 centimetres. And it must not have any problem being immersed in water of varying degrees of hot and cold. This is what the ISO 22810 standard, which has been in force since 2010, or its Swiss counterpart NIHS 92-20, requires.

Lack of knowledge even among manufacturers

You might think that such a watch can be worn while showering or swimming without any problems. But surprisingly, many watch manufacturers and jewelers communicate otherwise. They often say that a watch declared to be water resistant to 3 bar (30 meters) is only “splash-proof” and can only be “cleaned carefully with a damp cloth.” If you want to wear your watch while swimming, you should choose one that has been tested to at least 5 bar.

 

Does waterproof not always mean waterproof? If so, the term would be misleading. An inquiry to the watch association Fédération Horlogère (FH) provides clarification: the widely used statements are incorrect. A watch that is declared waterproof, étanche or water resistant can be worn for showering, swimming or snorkeling without any problem.

It is unclear why the marketing departments of watch manufacturers are still so cautious about communicating information. It may be because for a long time there was uncertainty about how much pressure actually develops in different water situations. It was previously assumed that the often very warm water pouring down when showering caused pressure peaks of up to 5 bar, which meant that there was a risk of moisture penetrating a watch tested for 2 bar. The same applies to a sudden impact with water.

But it has been known for 17 years that this is not true. In 2007, two engineers from the Swatch Group subsidiary ETA presented a study at the annual chronometry congress that showed that the pressure exerted on a watch in various water situations is much lower than previously assumed.

 

2 bar is enough for swimming

ETA engineers tested all the activities and situations that occur in aquatic environments: swimming, diving, splashing, diving from high dives. The tests were carried out using watch cases equipped with sensors at the position of the crown, the top and the case back. According to the measurements, the greatest overpressure on a watch occurs when jumping from a 10-meter diving board at the moment of immersion. But even then it is only 0.7 to 1.4 bar.

The summary of the publication states: “They (the tests) show that in all these situations, the actual stress values ​​on the watch are below the minimum criteria required by ISO 2281 (predecessor to ISO 22810). The tests contradict the information generally published to date.” In other words, testing a watch at 2 bar (20 metres) is enough to make it safe to use for all water activities (apart from diving).

Is it perhaps caution that leads many manufacturers not to set their customers’ expectations too high when it comes to the water resistance of their watches? It must be remembered that water resistance is not a permanent quality. Seals, particularly those made of rubber, show signs of ageing over time: they can lose their elasticity and the lubricant can evaporate. In addition, the seal on a crown is subject to friction every time it is used and therefore wears out. A watch that is water resistant today may suddenly no longer be water resistant tomorrow.

However, this information can be communicated openly to customers. At the same time, they can be advised that it is a good idea to visit a specialist retailer regularly to check the water resistance. Many offer this service, which is carried out using compressed air, free of charge. This is better than describing a watch as waterproof and then recommending in the small print not to wear it in water.

There are diving watches for diving

The results of the ETA tests also raise the question of whether it makes sense to specify different degrees of water resistance (3 bar, 5 bar, 10 bar). If all waterproof watches can withstand normal use in water without any problems, the usefulness of these specifications is questionable. Higher requirements are only necessary if a watch is used for diving. In this case, however, a high level of water resistance is not enough; the watch must meet additional safety requirements.

According to the ISO 6425 (NIHS 92-11) standard, diving watches must be water-resistant to 100 meters, with the tests being carried out with a safety margin of 25 percent. They also need a bezel to calculate the diving time. This can only be rotated in one direction so that the time underwater is not suddenly shown too low in the event of incorrect manipulation. They must also have particularly luminous hands and indices.

Patek Philippe simplifies water resistance information

Patek Philippe is a pioneer in simplifying water resistance specifications. For several months now, the Geneva-based luxury watch manufacturer has been declaring all of its waterproof models as “waterproof up to 30 meters.”

The argument is based on the findings of the aforementioned ETA study: “Waterproof certified watches allow the customer to wear the watch during the following daily activities: washing hands, showering, bathing, swimming and other activities in water, including diving to a depth of 30 meters, which corresponds to most applications,” says a statement from April. Patek’s is 30 instead of 20 meters because the company wants to set its own standard slightly above the ISO standard.

Even models like the Nautilus, which were previously considered waterproof to 120 meters, are now rated as waterproof to 30 meters, which initially unsettled fans of the brand. However, Patek emphasizes that nothing has changed in the actual construction of the watches – they are just no longer tested to 12 bar. According to Philip Barat, head of watch development at Patek Philippe, this is better for the watches. They would remain waterproof at 12 bar, but the high pressure could lead to the date being changed on watches with recessed correctors. For this reason, the company does not want to suggest to customers that the Nautilus is a suitable watch to be worn at a depth of 120 meters. There are diving watches for that.

According to Barat, the previous specification of 120 meters comes from a time when water resistance was not yet so widespread and could be used to differentiate oneself. The Nautilus collection was launched in 1976. Today, 3 bar is almost standard and is sufficient for most applications.

Enlightenment is needed

The conclusion is therefore simple: waterproof really does mean waterproof. And if a manufacturer describes a watch as waterproof, it cannot claim in the event of a warranty claim that it recommended that the customer take the watch off when swimming. The Fédération Horlogère will soon be launching an information campaign to better educate its members and the public on this topic.

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Supplement in the «Neue Zürcher Zeitung»

This article appeared on Friday, September 20, 2024, in the new NZZ focus “Watches & Jewelry”. Further current stories, reports and interviews from the 18-page supplement can be found in the e-paper of the “Neue Zürcher Zeitung”.