I have one toilet that is perspiring on both the outside of the tank and the bowl causing water to puddle on the floor. It seems that the temperature of the water is very cold but only in that one bathroom. What can I do to resolve the problem?

One solution for toilet sweating is to install a mixing valve in the inlet line. This mixes some "hot" water with the cold and brings the tank and bowl temperature closer to your ambient room temperature. Depending on your level of plumbing ability this can be a viable option.
If this sounds to difficult a simpler, but less effective option is to install a tank jacket that goes over the outside of the tank and acts as insulation.
Either of these items should be available at a good plumbing supply store.


Good Luck,
Morrowrj

The above is probably the best solution, another solution that is cheaper but a bit less effective is to line the inside of the water tank with syrofoam insulation board. It will prevent most of the cold from transferring from the water to the tank's outer surface, limitting the sweating. Apart from this it will also cut down on water use.

The best thing to do is find out why. Why is it sweating? Why is it cold? Is there a vent blowing on the bowl? Is there water entering that is chilled that much? Is there a place where outside air is entering this room? Is the water pipe in an outside wall that stays too cold? Would rerouting that pipe solve it?
My dad always taught me 'if you find out why, how becomes easy'.