You may be having a faulty how water heater or because of the sub zero tempatures a hot water pipe line that the cold is affecting the water line.
Try to discover the location and insulate or in some cases a trouble light near the line could give the area some relief until the tempatures rises about freezing.
Check the hot water heater do you have hot water ?
if you have running water , on cold nites try leaving the hot water line trinkle very slowly just to keep water movement
Call a local plumber for assistance if need be
Good luck JON E
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