If you can’t tell for sure if your toilet is leaking around the tank bolts or the tank is just sweating, add food coloring to the tank water.
After about an hour, touch the bolts and nuts under the tank with white tissue paper. If the tissue is colored, you have a leak – if not, it is condensation.
Repairing a leaking toilet is fairly simple. Repairing a sweating toilet is also simple. Make sure you turn off the water supply at the toilet before removing the toilet tank.