The first step in repairing a leaking toilet tank is to determine where the leak is located and what is causing it. There are several possible causes, the most obvious of which is a hairline crack in the tank ? often virtually undetectable. Other possible causes are the four factory penetrations at the bottom of the tank where connections are made to the water supply, where the tank is bolted to the bowl, and at the location where water flows from the tank to the bowl.

Each of these locations has a rubber washer designed to ensure a watertight connection. Over time the connections may become loose or the washers may deteriorate, requiring replacement.

An easy means of determining where the location of the leak is by placing a few drops of food coloring into the toilet tank. Wait about an hour and return to the scene to search for colored water at the outside of the tank. If the leak is at one of the factory penetrations, use a wrench and/or screwdriver to tighten the connection. Dry the area and return in another hour to see if the problem has been solved. If not, try replacing the washers.

Drain the tank by turning off the water supply and flushing the toilet. Disconnect the water supply and remove the two bolts that anchor the tank to the bowl. Clean the connections and openings with a soft dry cloth and install new washers. Also install a new washer where the tank discharges into the bowl.

Before you get set on tearing out your toilet tank, be certain that your leak isn't a sweating tank!

A sweating tank is caused by condensation that occurs on the outside surface of the toilet tank due to the difference in temperature between the water in the toilet tank and the air in the room. If the problem is in fact condensation, it can be remedied in one of two ways ? with a tank liner or a tempering valve.

The tank liner consists of a rubber membrane that is installed in the interior surface of the tank as a layer of insulation. The tempering valve is a bit more complicated. It requires removing the existing water supply valve and replacing it with a model that mixes a small amount of hot water so that the water in the tank isn't so cold, thus eliminating condensation. The former is a common do-it-yourself project, whereas the latter often requires a plumber.