Pressure Testing
Water Resistance


A Chronosport UDT being pressure tested.

At BfW PRESSURE TESTING is included in the complete service of all watches marked "divers" & "water resistant

CAUTION:  WATER will RUIN your watch! 

Much confusion exists among the general public with regards to the concept of 'water resistance' as it pertains to watch cases.  The Internet is full of misinformation on this topic, particlularly regarding watches with minimal water resistnace.  When a watch case is marked only 'water resistant' or '3 ATM' or '3 BAR' or '30 M' or '30 METERS' this does NOT mean that you can take your watch under water up to 100 feet!  That is NOT what the rating is designed to reflect.  YES, it may be confusing.  NO, we are not in control of the ISO 2281 or ISO 6425 standards or their designations. 

The source of confusion stems from the actual testing process for water resistance, which is performed in LABORATORY conditions with static (non-moving) water.  MOVING water may exert additional FORCE that can increases the overpressure exerted on a watch case, such as when the watch is exposed to high pressure water from a high-tech shower head.

In addition, watches manufactured to meet the minimal 30M/3ATM standard typically have poorly engineered crown/case tube components, undersized/weak crown and/or caseback gaskets, cemented crystals, and/or inferior case/bezel assembly.  They may have met the minimal standard when NEW, but will absolutely FAIL to meet the standard once they have been in service for a short period of time on the average American wrist.  Add an abusive and/or 'uneducated' owner and/or an incompetent jeweler, and you now know why these watches will leak and/or flood when exposed to a swimming pool or shower - and also now know why no watch manufacturer will state that this minimum level of water resistance is recommended for swimming or the shower.    

If you want to know the truth about this subject, but do not want to spend several hours truly educating yourself about this topic from credible sources, we suggest you utilize the table below as a guide in your decision making regarding what YOU decide to subject YOUR watch to, AND more importantly, what risk YOU are willing to fully assume with YOUR watch.

SOURCE = Wikipedia (

Water Resistance (WR) Rating Suitability Remarks
'Water Resistant'
or 30 m
Suitable for everyday use. Splash/rain resistant. NOT suitable for swimming, snorkeling, water related work and fishing. NOT suitable for diving.
WR 50 m Suitable for swimming, white water rafting, non-snorkeling water related work, and fishing. NOT suitable for diving.
WR 100 m Suitable for recreational surfing, swimming, snorkeling, sailing and water sports. NOT suitable for diving.
WR 200 m Suitable for professional marine activity and serious surface water sports. NOT suitable for diving.
Diver's 100 m Minimum ISO standard (ISO 6425) for scuba diving at depths NOT suitable for saturatin diving. Diver's 100 m and 150 m watches are generally old(er) watches.
Diver's 200 m or 300 m Suitable for scuba diving at depths NOT suitable for saturation diving. Typical ratings for contemporary diver's watches.
Diver's 300+ m for mixed-gas diving Suitable for saturation diving (helium enriched environment). Watches designed for mixed-gas diving will have the DIVER’S WATCH L M FOR MIXED-GAS DIVING additional marking to point this out.
Inspite of this table, we do NOT recommend you take ANY watch under water unless it also has a 'screw-down' crown, as the weak point in most watches is the little o-ring gasket situated in the watch crown (knob you set the time with).  This o-ring fails in 90% of the watches we see with water damage.

Your "water resistant" watch should be pressure tested everytime the case is opened to peform ANY inspection or service.  Many watch-repair shops and jewelry stores do NOT understand, own or utilize this expensive equipment, so it is "buyer beware."  This is the #1 reason why you have moisture in your watch, a fogged crystal, or are noticing water droplets on the dial or hands - poor and/or substandard service!

Every MODERN watch we repair at BfW which is marked "water resitant" is tested to verify the watch case water resistance to the manufacturer's rating.  This testing is conducted with either state-of-the-art "dry" testing, and/or "wet" testing.   

BfW's owner and president, John W. Safranek, recently wrote an article on water resistance testing which was published in AWCI's "Horological Times" magazine.  You can read Mr. Safranek's article at this link:

"Water Resistance Watch Case Testing"

If your watch was opened and/or repaired at a jewelry store and/or by a watchmaker who did NOT pressure test your watch, and you desire to have your watch's rated water resistance verified, we offer stand-alone pressure testing service at three (3) levels:

Level 1 Pressure Test Service 
will dry test a watch rated at or below 100m/10Bar. 

Level 2 Pressure Test Service will both dry and wet test a watch rated over 100m/10bar and up to 1000m/100bar.  

Level 3 Gasket/O-ring Service will replace any rubber o-rings that may have failed the respective pressure tests, and will be required if your watch fails the test due to a faulty sealing and/or o-ring gasket(s).

Below are some photos of the actual equipment we utilize in the "dry" and "wet" testing process of watches via sophisticated vacuum, pressure and leak detection equipment on water resistant and "dive" watches.  We also can print a RECEIPT and/or photo-document that your watch passed these critical verification tests for water resistance.

The preliminary "dry-test" machine running both
vacuum and pressure tests
on a dive watch.

A close-up of the results of a pressure test at our facility.

A verification receipt of the test results.

For DIVE watches rated at 100m/10 bar/10 atm or
, a specialized "wet test" of water resistance
up to 125 bar (1250 meters) is also performed,
per the manufacturer's requirements.  To see a
video of this new and unique tester,
click here.

If a leak were detected, this machine would safely
locate it  without risking any damage to the watch.

One of our watchmakers would then further analyze and
correct the problem, repeating the tests until your 'diver's rated' watch
was verified as "water resistant" to 125% of its rating

BestFix Watch Company is a state-of-the-art watch-repair facility.  If you have any questions, please use the ASK the Watchmaker Form.

BfW Co. Inc.


Copyright © 2020. All Rights Reserved.