A watch marked 50 metres can still take on water while you are washing the car. That is not necessarily a fault in the rating - it is often a misunderstanding of what the number means, or a sign that ageing seals need attention. Before you test watch water resistance at home, understand what your watch is designed to handle and where a professional pressure test makes more sense.

Water damage is one of the most preventable watch repairs. It can affect the movement, dial, hands and battery, and corrosion may continue long after the moisture first enters. A few careful checks now can save a favourite everyday watch, gift piece or sports model from a much bigger repair later.

Read the water-resistance rating first

The rating on the dial or caseback is your starting point. It describes the level of water pressure the watch was designed to withstand under controlled conditions. It is not always a literal guide to the depth you can wear it at in every situation.

A watch marked 30m or 3 ATM is generally best kept away from water. It may tolerate a brief splash or rain shower, but it is not a swimming watch. 50m or 5 ATM suits everyday splashes and, depending on the manufacturer, light surface swimming. 100m or 10 ATM is a more confident choice for swimming and water sports. 200m and above is commonly built for more serious aquatic use, although a dedicated diver's watch may also have additional features and testing standards.

The key detail is pressure. Moving your arm through water, jumping into a pool or directing a tap at the case can create more pressure than a calm, static depth suggests. Hot water, steam and soap also place extra strain on seals. That is why a 50m fashion watch may be fine around rain and handwashing but still be a poor choice for a spa, hot shower or regular laps.

What you can check before you test watch water resistance

There are useful checks you can make without putting the watch anywhere near water. They do not prove water resistance, but they can reveal obvious reasons not to risk it.

Start with the crown. On a standard push-pull crown, make sure it is pressed fully into the case. If the watch has a screw-down crown, turn it clockwise gently until it is properly secured. Do not overtighten it. An open crown is one of the fastest ways for water to enter a watch.

Inspect the crystal and case for chips, cracks or gaps. A small crack at the edge of the glass can compromise the seal. Check that the caseback sits evenly and that pushers are not loose or sticking. On a watch with chronograph buttons, do not operate the pushers underwater unless the manufacturer specifically confirms this is safe.

Age matters too. Water resistance is not permanent. Gaskets around the crown, crystal, caseback and pushers are designed to compress and seal, but they gradually dry out, flatten or wear. A watch that survived a beach holiday five years ago may not offer the same protection now, especially if it has had a battery replacement or a knock since then.

Why the glass-of-water test is a bad idea

A common online suggestion is to place a watch in a glass or bowl of water and wait for bubbles or condensation. It sounds simple, but it is not a reliable way to test a watch - and it can turn a small seal issue into a damaged movement.

Bubbles may come from the bracelet, case edges or trapped air rather than a genuine leak. More importantly, water entering the watch may not be immediately visible. By the time you see fog under the crystal, moisture may already be affecting internal components.

Avoid shower tests, sink tests and pool tests as well. Water resistance should never be proven by exposing an unknown or overdue watch to water. If the watch has sentimental value, a mechanical movement or a high replacement cost, the risk is simply not worth it.

The safe way to test watch water resistance

A professional pressure test checks the case in controlled equipment, without relying on guesswork. Depending on the watch and workshop setup, the test may use air pressure, water pressure or both. The aim is to identify whether the case seals remain intact at the pressure level relevant to the watch's rating.

Dry pressure testing is often preferred as an initial check because it can detect a leak without putting water directly around the watch. If the case fails, the technician can inspect likely causes before any moisture reaches the movement. Wet testing may be used as part of a more detailed process, particularly after a successful dry test.

A proper assessment should account for the crown, caseback, crystal, pushers and helium valve where applicable. If a leak is found, the solution may be as straightforward as replacing a gasket, resealing the caseback or fitting a new crown seal. If the crystal is damaged or a pusher tube is worn, more extensive repair may be needed.

At Watch Express, on-site watch repair support is available in Blacktown for owners who want a practical inspection, battery replacement, reseal or repair advice without taking chances at home. For customers outside the area, postal repair options make it easier to have a watch assessed before the next swim, trip or outdoor season.

When should your watch be pressure tested?

There is no single schedule that suits every watch. How often you need a test depends on the model, its water rating, its age and how you wear it. A watch used only in an office has very different exposure from a G-SHOCK worn for surfing, training and weekend adventures.

As a general rule, arrange a water-resistance check after a battery replacement, caseback opening, crystal replacement or crown repair. Any time the case is opened, its seals should be inspected and correctly refitted. It is also wise to test a watch before a beach holiday or regular swimming season if you rely on it in the water.

Book an inspection promptly if you notice condensation under the crystal, a crown that feels unusually loose, a damaged crystal or sudden moisture after rain. Even a small amount of fogging deserves attention. Remove the watch, avoid pressing buttons or pulling out the crown, and have it assessed as soon as possible. Do not place it in rice, on a heater or in direct sunlight. Heat can worsen the damage and rice does not repair compromised seals.

Everyday habits that protect the seals

Water resistance lasts longer when the watch is treated with the same care as any other precision accessory. Rinse a watch rated for swimming with fresh water after saltwater exposure, then dry it with a soft cloth. Salt, chlorine, sunscreen and sand can all leave residue around the crown and pushers.

Keep the crown closed before water contact, and never adjust it in the pool or sea. Avoid wearing a non-diving watch in a hot shower, sauna or spa. Sudden temperature changes can affect internal pressure and seal performance, while soap can reduce the life of rubber gaskets.

If you rotate between watches, store them somewhere dry and protected from knocks. A watch box or roll keeps crowns, crystals and bracelets from rubbing against other items. It will not replace servicing, but it helps prevent the accidental damage that can compromise a case seal.

Water resistance is a service item, not a lifetime promise

A water rating is a useful buying guide, but it should not be treated as a permanent guarantee. Seals age, crowns wear and everyday impacts add up. The right approach is simple: choose a rating that matches how you actually live, avoid risky home tests and arrange a pressure check whenever the case has been opened or the watch is due for water use.

That small bit of maintenance lets you wear your watch with confidence - whether it is keeping time through a Western Sydney downpour, a day at the beach or your next holiday by the pool.