Answers (3)
when water freezes in copper pipes or metal pipes the water expands, therefore the expanding frozen water bursts the pipe.
It's because the water freezes and the copper pipe can't handle the expansion and cracks or bursts. We had this happen to us and it was awful to get through the winter without our hot water. We live in an area that is apt to get cold often so we decided to reline our pipes so that it would not happen again.
abe chup