Toilet tank troubles? No sweat

Answer: This is a common condition in hot, humid weather. The sweating on the water tank of the toilet is from condensation caused by warm, humid air coming in contact with the cold porcelain surface of the tank. The tank is cold from water flowing into it. The phenomenon is the same as you get when a glass of ice water is exposed to warm, humid weather. Warm air holds more humidity than cold air, so when it cools down it releases its moisture.

Sometimes this can be prevented by enclosing the outside of your toilet tank with fabric material, such as the terry cloth tank covers available at many bath shops. The condensation can also be reduced if you use a ventilating fan in the bathroom or run the air conditioner (which can become a costly solution). Running a dehumidifier can also help, but it's difficult to dehumidify the bathroom on a hot day when other house windows are open.

One of the most effective methods of eliminating condensation is to raise the temperature of the water before it reaches the flush tank. A specially designed mixing valve is available. It can be installed in the cold-water line supplying the flush tank. This tempering valve allows you to connect a hot-water line to the cold line so that the water delivered to the tank will be room temperature. If the surface of the tank is no colder than the surrounding air, condensation will not form. A tempering valve only takes a few hours to install - if the hot and cold water lines are easily accessible. Only a little bit of hot water is used in each flush, so the tempering valve adds only a few cents a day to your energy bill. The valves are available at plumbing supply stores and usually run around $60 or less.

Another solution is the installation of a tempering tank. Designed to accomplish the same thing as a tempering valve, a tempering tank is simply a reservoir in the cold-water line that supplies the flush tank. Theoretically, water allowed to stand in this tank will be warmed by surrounding air. However, this won't work if large amounts of water must pass through the tank within a short time. Also, condensation will form on the tempering tank so this type of installation simply changes the location of your problem from the bathroom to the area where the tempering tank is located. You will also need a satisfactory area to locate the tank, such as basement.

One of the simplest solutions to a condensation problem involves no plumbing modification. An electric immersion heating unit with a self-contained thermostat will keep the water in the flush tank at a sufficiently high temperature to prevent the formation of condensation.

A 120-watt aquarium heater placed in the tank will be sufficient. You can mount one using suction cup holders inside the water tank. The heater takes about an hour to raise the tank temperature above the condensation point, so you may get some dripping in the meantime. Also, condensation will continue to form on the supply line since it's filled with cold water. Take safety precautions if you opt for this solution. Be sure the connecting cord will not be damaged by the tank lid and that there is a grounded electrical outlet nearby.

When replacing old fixtures, give some consideration to installing a dripless tank featuring two walls with an insulating sealed airspace between them. Another solution to a dripping tank is the installation of a drip tray underneath the tank. This won't stop the condensation, but the tray will catch the moisture and collect it in removable cups or a drain that empties into the bowl of the toilet. Metal or plastic trays can be installed in a matter of minutes.

It is important not to let this condition go unchecked. Excessive moisture collecting and penetrating the floor at the base of the toilet can cause serious damage over time.

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