Dear Student
The reason many water pipes burst is because water expands as it freezes. This can be attributed to the property of Anomalous Expansion of water.
Whereas, water pipes contracts on cooling. If the expansion of water occurs in a closed environment such as a water pipe, there could be substantial pressure placed on the inner walls of the pipe material, whether it be iron, lead or PVC plastic. Even if a pipe is strong enough to handle the occasional stress of frozen water, the cumulative effect can weaken the structural integrity of the pipe and eventually, it will burst.
It is due to the expanding property of water as it freezes due to very cold weather the above said bursting of water pipes occurs.
Regards