It may be a point of curiosity when you start to notice that your toilet tank seems to be sweating. However, when you notice how much water seems to be dripping onto the bathroom floor, you may wonder whether something more serious is happening. The "sweat" you see is water that appears as a result of very humid air hitting that nice cool tank; it's condensation in action. If this happens often, water could end up seeping beneath the floor and ruining the plywood. Many solutions exist for fixing sweaty tanks, including the ideas below.
Sometimes, the easiest way to handle condensation is to cover the tank. That warms it up a bit, and, depending on the material you use, absorbs water too. Terry cloth tank covers exist for just this purpose.
2-Turn on the Fan
Remembering to keep air flowing can sometimes help avoid sweaty tanks. Your bathroom's vent fan or a small table fan could be effective.
The flapper inside the tank could be constantly leaking cold water into the tank, making the temperature cooler and just perfect for condensation. To look for flapper leakage, put some food coloring in the main tank. If, over a few hours, you see that color in the toilet itself, there's your proof. To stop this leakage, which shouldn't be happening, get a new flapper from a regular home improvement store and install it.
4-Get a Tempering Valve
Also called an "anti-sweat" valve, this valve helps you introduce hot water to the tank so that the water sitting there isn't cold enough to trigger condensation. Typically, your toilet will only be fed by the cold water line in the house, but a tempering valve will permit hot water line to also feed into the toilet. When the environment temperature drops, and condensation doesn't really happen anymore, the hot water knob can be turned off. If you're not confident about your own skills, you can have a plumber install the piece for you.
5-Have an Interior Tank Installed
If your weather is always warm and humid, you may consider a tempering tank to prevent any condensation. The tank will go in the interior of your existing toilet tank and serve as an internal holding tank so that the exterior tank isn't as cool.
With these attempts, condensation may stop being an issue. If you still need help with this or with other toilet repairs, your plumber can visit and handle everything.