The hot and cold copper supply lines to our laundry sink both ruptured at the same time. Though we have had colder than normal temps these lines are interior and would not be exposed to freezing temps. The lines are over 20 years old and we have very hard water. They are "teed" from the supply lines to our washer. Before I repair the lines I would like to have some idea as to what would have caused the failures. Should I just consider it old age/ corrosion or could it be a system problem related to higher than normal water pressure. We have a pressure regulator on the main supply line. Would you expect a problem with it? It was replaced approximately 10 years ago. Thanks for your help.