i wouldn't mess with nature, most water pipes are copper and they can conduct significant amount of heat. This means the standing water in the pipes can quickly lose its heat and freeze, perhaps even faster THAN on a concrete floor out in the open. If you even wrapped that in the thickest blankest it will still freeze, it just needs a bit more time. This is because the water it self doesn't have enough heat for the blanket to prevent escaping. it's Not like the human body where blood circulation is constantly generating heat, and so insulating ourselves can raise our ambient body temperature.
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