What is a watch pressure test?

A pressure test uses a specialised machine to apply controlled air pressure to the watch case and then checks whether the case holds that pressure without leaking. It takes under 5 minutes and can be done with the watch fully assembled — no case-back removal needed. It directly confirms whether the seals are intact, rather than relying on the original factory rating stamped on the caseback.

How often should I have my watch pressure tested?

Once a year is the standard recommendation for any watch you regularly expose to water. If you only wear your watch on dry land, every two to three years is acceptable. After every battery change or case-back opening, a pressure test is essential regardless of how recently the last one was done — opening the case always disturbs the gasket.

Does a battery replacement affect my watch's water resistance?

Yes. Every time the case-back is opened — for a battery change, servicing, or any reason — the gasket is disturbed and may not reseal perfectly. A competent watchmaker will inspect and often replace the gasket, then retest water resistance after reassembly. Always ask whether a pressure test is included when having a battery changed.

Watch Pressure Testing Explained: What It Is and When You Need It

The Gap Between the Rating and Reality

A watch marked “10 ATM” or “100m” on the caseback is telling you what it was rated to when new. Gaskets age. Battery changes disturb seals. Temperature cycles compress rubber. Within two to three years of normal use, the actual water resistance of most watches has quietly degraded from the factory rating — sometimes to a fraction of it.

A pressure test is the only way to know the real number. It takes under five minutes, costs very little, and is by far the cheapest insurance against moisture damage that can write off a watch entirely.

What Happens During a Pressure Test

Air pressure is applied to the case

The watch is placed in a sealed pressure chamber. Controlled air pressure is applied to the exterior of the case — simulating the pressure of water at a given depth. The machine raises the pressure to the watch’s rated level and holds it there.

Pressure drop is measured

If the seals are intact, pressure inside and outside the case equilibrates — no air passes in. If the seals have failed, the pressure reading drops as air finds its way through the gasket. The machine records the rate of pressure drop and compares it to tolerance limits for the rated depth.

Pass or fail — immediate result

The test produces a clear pass or fail result within a few minutes. No case-back removal is needed, no disassembly, no water involved. If the watch passes, you have a confirmed seal rating. If it fails, the watchmaker can open the case, inspect the gasket, replace it if needed, and retest.

Gasket replacement and retest (if needed)

A failed test usually means the gasket has compressed or cracked. Replacement gaskets are inexpensive — it is the labour of identifying the correct gasket, fitting it correctly, and retesting that takes skill. After a new gasket is fitted, the test is repeated to confirm the watch is sealed to its rated level before it leaves the workshop.

Air pressure, not water: Professional pressure testing uses air, not water. Air reveals seal failures without risk of actually getting water inside during the test itself. A few workshops use water-based testing, but the industry standard for service centres is a dry air pressure chamber.

When You Need a Pressure Test

1

After every battery change — opening the case-back always disturbs the gasket, even slightly. A battery change without a subsequent pressure test leaves the water resistance unverified. Always ask your watchmaker whether the test is included.
2

After any case opening — whether for servicing, crystal replacement, or crown repair. Any time the case is opened and resealed, the seal must be verified before the watch goes near water.
3

Once a year if you swim with your watch — regular swimmers and divers should have the water resistance confirmed annually. Saltwater is particularly aggressive on seals, and the pressure changes involved in swimming and diving accelerate gasket wear.
4

Every two to three years as routine maintenance — even if you never wear your watch near water, a periodic pressure test identifies ageing gaskets before they fail completely. Gaskets typically need replacement every three to five years regardless of use.
5

After any impact or crystal crack — a hard knock, even one that leaves no visible damage, can dislodge or distort a gasket. A cracked crystal removes the seal entirely. Both require immediate pressure testing after repair.

The battery change trap: Most people get a battery changed at the nearest shop without asking whether a pressure test is included. Many battery change services do not include gasket inspection or pressure testing. If you swim or shower with your watch, this is the most common route to moisture damage we see in our workshop.

What ATM Ratings Mean in Practice

Rating	Pressure	Safe for	Not safe for
3 ATM / 30m	3 bar	Rain, hand washing	Swimming, showers
5 ATM / 50m	5 bar	Swimming (surface)	Diving, snorkelling
10 ATM / 100m	10 bar	Swimming, snorkelling	Scuba diving
20 ATM / 200m	20 bar	Recreational scuba	Deep diving (needs ISO 6425)
Diver’s (ISO 6425)	200m+	Professional diving	—

These ratings assume intact, unaged gaskets. A watch rated 10 ATM with a two-year-old gasket that has never been checked may effectively be 3 ATM. The only way to know is a pressure test.

5 Signs Your Watch May Have a Failing Seal

Fogging inside the crystal

The most visible sign: condensation on the inside of the glass, especially after temperature changes. This means moisture is already inside. Act immediately — every hour increases corrosion risk.

Visible moisture under the dial

Water droplets visible through the crystal, or the dial showing signs of water staining or running colour, mean the case is fully compromised. Requires immediate disassembly and drying.

Sudden timekeeping errors after swimming

If a watch that keeps good time starts running slow or fast after water exposure, moisture may have reached the movement. Quartz movements are particularly sensitive to moisture on the circuit board and battery contacts.

Battery draining unusually fast

Moisture creates short circuits on quartz movement contacts, draining batteries far faster than normal. A battery that should last 2 years failing in 3 months is a moisture-exposure indicator.

Corrosion spots on the dial or hands

Rust-coloured spots or discolouration on the dial, hands, or inside the crystal are signs of past moisture ingress. Even after drying, corrosion continues internally unless the movement is professionally cleaned.

Prevention costs almost nothing: A pressure test at Iglisi Watch takes about 5 minutes. It costs a fraction of what gasket replacement plus movement cleaning costs after moisture has entered the case. If you own a watch you care about, make pressure testing a routine part of its care — the same way you service a car rather than wait for a breakdown.

Get Your Watch Pressure Tested in Durrës

Walk in to our workshop on Rruga Aleksander Goga. We test water resistance on-site with a professional pressure chamber — no appointment needed. We inspect the gasket, replace it if necessary, and retest before the watch leaves the bench. Family-owned and trusted since 2009.

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Rruga Aleksander Goga · Durrës 2001 · Albania · +355 67 636 0510

Published by Iglisi Watch · Durrës, Albania · June 2026. ATM ratings follow ISO 22810 (water resistance) and ISO 6425 (diver’s watches) standards. Actual seal performance depends on gasket condition at time of use.