When Toilet Tank Leaks, Determine the Cause First

Question: How do I change a leaking toilet tank?

Answer: 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 might become loose or the washers might deteriorate, requiring replacement.

An easy means of determining 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 or a screwdriver to tighten the connection.

Dry the area and return in another hour to see if the problem has been solved. If it hasn’t been, 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 tear out your toilet tank, be certain that your leak isn’t a sweating tank. This condition is caused by condensation that occurs on the outside surface of the tank because of 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. This eliminates condensation. The former is a common do-it-yourself project, whereas the latter often requires a plumber.

A Clog in the Sewer Line May Be Causing Problem

Q: I have a plumbing problem wherein the toilet appears to bubble up water, and the bowl completely fills with water upon flushing. It requires about 30 minutes for the water to drain out. When it does, it almost completely drains out. I have tried using a plunger, but to no avail. Please advise.

A: You might have a clog somewhere in your sewer line. To clear it, do the following: First get a mirror and use it to look deep into your toilet’s drain. If you see nothing, remove the toilet and see if anything is stuck in the lower portion of its drain.

If the toilet is OK, then the next step is to use a closet auger (a short, flexible coil-spring cable that is used to dislodge debris in a sewer line).

It’s usually safe for a do-it-yourselfer to attempt to dislodge debris with a closet auger. A closet auger is made for short cleaning runs and doesn’t have the potential to damage a sewer line like the full-sized model. The sales clerk at the hardware store can explain how to use the smaller device.

Once the sewer line has been cleaned, the toilet will have to be reinstalled. Don’t forget to use a new wax ring to create a watertight seal between the toilet and the sewer line. The old wax ring will almost certainly leak. A closet auger often solves the problem--eliminating the need to call a plumber.

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