: He boiled a gallon of water and stirred in a heavy dose of kosher salt. Salt lowers the freezing point of water, acting like a liquid ice-melt for the pipes.
If the ice is further down the line:
A frozen bathtub drain is a manageable problem if caught early. By using gentle heat and avoiding dangerous methods like boiling water or open flames, you can restore your plumbing safely and keep your home running smoothly all winter long. frozen bathtub drain pipe