Defective commodes cause the greatest amount of water loss in the home and are very difficult to detect. Most people are surprised to learn that a defective commode can waste as much as 216,000 gallons of water in a month. Either a defective supply valve or improper sealing of the rubber tank ball on the opening causes the most common leaks.

The correct water level in the tank is about one-half inch below the top of the overflow pipe. If water is up to the top, it is almost certainly overflowing. To check the supply valve:

• Remove the cover of the tank;
• Look to see whether water is running down the overflow pipe. If is is, check the rod. If it is bent upward, it may prevent the tank float from reaching its full heigh and will allow leakage through the open valve. If necessary, straighten the rod and apply oil to lever joints;
• Install a new supply valve. 

The most difficult leak to detect occurs at the discharge opening at the bottom of the tank. If the rubber tank ball does not fit tightly over this opening, a defective ball, irregular seat, or bent lift wires may be responsible. Check for leaks of this type overnight by using either of these simple tests:

• Place food coloring or bluing in the tank and look in the toilet bowl for traces of food coloring;
• Turn off the valve directly under the commode tank, leave it off overnight and make sure the tank is still full in the morning.

If food coloring is in the toilet bowl or if the water level has dropped, repairs are needed.

How to determine which repairs are needed

The ball needs to drop right into the hollowed seat of the discharge opening. Check the ball to make sure it:

• is not worn-out or misshapen
• has not lost its elasticity.

Sometimes the ball is covered with a slimy coating, which can be easily wiped off. However, if the ball fails to drop right into the hollowed seat, it should be replaced with a new one.

If the collar of the discharge opening is corroded or grit-covered, scrape and sandpaper collar until smooth, so it forms a uniform bearing for the stopper.

If the lift wires are bent, straighten or replace bent lift wires so that the ball drops squarely into the hollowed seat.