One last vital piece of data to remember is that water resistance is not permanent
. Gaskets could possibly be damaged or misshapen, cases should be dented through normal use or crystals loosened or cracked. In order to preserve the water resistance of a timepiece you {must|should|ought to|need to|have to| be sure to do preventive maintenance. At least once a year you should take your timepiece in for service, so that it can easily be tested and make certain that there are no leaks.