I'd like to insulate because in winter the incoming supply of water is
fairly cold. My basement is unheated which doesn't give the supply pipes a
chance to warm up at all. When this water settles in the toilet tank, the
difference in temperature between the water in the tank and the ambient air
in the bathroom causes the tank to sweat a lot. When the tank was insulated
before it cut down on the amount of dripping water I had to towel up
continually.