I am assuming you have an old toilet, one that uses a full 3.5 gallon tank of water per flush which of course requires a complete refill of water with each flush. Most folks have found that a low flow toilet wish uses 1.6 gallons (even less on the newer ones) do not have a sweating problem. Here's why. The water in the tank is at or near room temperature. A low flow toilet by design uses only half of that water in the tank for a flush. Therefore only 1.6 gallons of new, cold water is required to refill the tank. This colder water mixes with the room temperature water that is still in the tank. This results in the water in the tank, while now somewhat below room temperature, is still warmer than it would be if the entire tanks had to be refilled.