If you haven’t done so, you might want to read How To Fix A Running Toilet, Part 1; How To Fix A Running Toilet, Part 2 and How to Fix A Running Toilet, Part 3. Some of the most common problems are addressed in those sections. But if you’ve read them all and are still beating your head against a wall, keep reading.

Step Six: Examine The Toilet Overflow Tube.

The Overflow Tube is the long, hollow, tower-looking pipe that stands up vertically within the toilet tank, usually located in the middle of the tank. It’s designed as a fail safe device that prevents the tank from overflowing with water if something goes wrong. Actually, if your toilet is constantly running you should be thankful for this little tube, as it’s what’s sending that excess water down to the bowl rather than over the top of the tank lid.

Take a look at the tube. Is the water level high enough so that it’s overflowing into it? If so, the toilet mechanical systems are malfunctioning and not stopping the water supply!

If the water level isn’t near the over flow tube, you can skip ahead to How To Fix A Running Toilet, Part 5. Otherwise, read on!

Step Seven: Test The Toilet Fill Valve.

Before attempting this next step, check the toilet float and float arm assembly again (it’s discussed in How To Fix A Running Toilet, Part 3).

If the toilet float and float are are working properly, there’s a good chance the fill valve is leaky or has failed. The Fill Valve is another vertical, tower-like mechanical piece that refills the tank after/during a flush. It’s easy to identify because the float is attached to it.

If the Fill Valve fails, the it won’t shut off the water supply. Fortunately there’s a very easy way to test this.

Start by shutting the off the water supply to the toilet, which is usually controlled by an easily accessible valve along the toilet’s water supply line. With the water supply shut off, flush the toilet. You’ll notice that once the water left the tank, it never refilled. That’s good – that’s what we want.

Step Eight: Examine The Toilet Fill Valve.

This next step requires both hands, but it isn’t tricky. With one hand, raise the float to it’s highest position. With the other, open up the water supply valve outside of the toilet. It’s important to keep the float at it’s highest position because it tricks the toilet fill valve into thinking the tank is full.

Now, examine the toilet fill valve. There shouldn’t be any water coming out of it at all. If there is, you’ve got a leaky toilet fill valve. These are simple and inexpensive to replace.

Go ahead and let the float drop after you’re done examining. It will fill the toilet tank back up with water so you can use the toilet again.

Still can’t find the problem? Click on over to Part 5.

If you haven’t read How To Fix a Running Toilet, Part 1 and How To Fix A Running Toilet, Part 2, take a minute and do so. Those sections cover some of the most common problems. But if they don’t address your situation, read on!

Step Four: Examine the Float.

The float is the big buoyant ’thing’ that floats on top of the tank’s water supply. As the water level lowers, it triggers a mechanism to let more water into the tank. Once the water level reaches its highest point, the float (and its mechanism) shut the water supply off.

Sometimes the float gets damaged and doesn’t float on the surface of the water. Because it doesn’t reach its highest point, it never tells the other mechanisms to stop the flow of water. Examine the float both visually and by hand. Look and feel for any cracks or leaks, and also determine if the float is empty. It should be nearly as light as a feather when it’s water tight, but if water has crept in it will become heavier.

Step Five: Examine the Float Arm.

The float arm is simply a long rod (usually metal) that joins the float to the other mechanical parts of the toilet. It’s rare, but sometimes the arm gets bent out of shape. If you’ve examined the float and found that it is water tight, it’s possible that a bent arm is the culprit.

Grab the float and gently raise it. If it successfully shuts the water off, you’ve found the problem! Check to see if the arm is adjustable. If it is, shape the arm so that the water shuts off once the float reaches the highest water level (not so high that water flows over the overflow tube). Some arms are adjustable and some aren’t, so don’t press your luck if your isn’t – simply buy a new float and arm at a local hardware or department store. They are cheap (usually only a couple of bucks).

Not the float? Let’s address some other possibilities in Part 4.