Q: When it’s really cold outside — in the 20s or lower — the toilet tank in my powder room develops so much condensation that it drips onto the floor in a measurable amount. The condensation forms only on the side of the tank that’s connected to the water line, which runs in an insulated cavity along a joist from where water comes into the basement. The other side of the tank, adjacent to the vanity, remains dry. The toilet is on an outside wall on the main floor, above the unfinished part of my basement. What can I do to prevent this from happening? Would wrapping the water line with insulating tape work?