* How to Fix a Running Toilet

Is your toilet running? Well, then you better go catch it!

Dad jokes aside, a constantly running toilet can be an annoying—and expensive—problem to have.

Learn how to fix this issue before the cost of a running toilet catches up with you.

How to Fix a Running Toilet

What Are the Common Causes of a Running Toilet?

It is normal for a toilet to run for a few seconds as it is being flushed. However, if your toilet continues to run after this time has elapsed, it can be an issue which raises your water bill and even possibly causes the toilet to overflow and flood the bathroom floor with water. Luckily, fixing a running toilet is often pretty simple and can be done without resorting to a call to the plumber!

There are a few reasons why a toilet may continue to run after the normal flush cycle.

Here are three of the most common (and easy to fix) ones.

Common Cause #1: The Flapper

The most likely cause of a running toilet is a defective or deteriorated flapper.

The flapper is a stopper made of rubber which opens when the toilet is flushed to allow clean water to refill the toilet bowl. When the flapper wears out or is misaligned, it cannot seal up over the hole properly. That, in turn, allows water to refill the toilet bowl constantly instead of stopping once the water has reached the right level in the bowl.

You can tell that this is the issue by removing the toilet tank’s lid and pressing down on the flapper, which is located at the bottom of the tank. If the water stops running into the bowl right away, then the flapper is at fault.

Note that the flapper chain may also be at fault. If the chain is too short or becomes tangled up, then it may not be long enough to allow the flapper to close completely. Check that the chain is the right length and is not tangled up, too.

Common Cause #2: The Float

Another common cause of a running toilet is a float which is set too high. Depending on how old your toilet is, you may either have a ball float or a cup float. When you open the lid of the tank, you should clearly see the float, which is attached to the tall refill tube, often on the left-hand side of the tank.

Regardless of which type of float you have, if it is set too high, it will force the water level to keep rising above the overflow pipe, which will cause the tank to drain continuously into the bowl. If this is the case, the float’s height will need to be adjusted so that it is set lower in the tank.

You can check to see if this is the problem by quickly adjusting the height. On a ball float, simply press down gently on the arm of the float to see if that stops the water from running. On a cup float, find the adjustment mechanism (which may be a clip on the side of the cup) and open this mechanism while sliding the float a small way down the central tube to see if the water stops running.

Common Cause #3: The Fill Tube

If neither of the above causes seems to be the problem, the issue may be with the toilet’s fill tube. This tube runs from one pipe—the fill valve—to another—the overflow tube. If this tube isn’t in the right spot, it may cause the toilet to overflow.

The fill tube should be about an inch above the water in the tank and firmly connected to the fill valve. To make sure that this tube is working correctly, flush the toilet and watch the water as it goes through the tube. The water should go directly into the overflow tube.

If it does not, or if the tube is underwater, then this is likely why your toilet is running.

How to Fix a Running Toilet

Now that you know the common causes of a running toilet, let’s take a look at how to actually fix the problem.

Step 1: Determine the Cause

Because the solution to fixing a running toilet is so dependent upon what is causing the issue, you will first need to identify why your toilet is not working properly.

First, open the lid of the tank.

Next, try flushing the toilet and watching the process. See if you can identify what is going wrong based on the details provided in the previous section of this article.

Step 2: Adjust or Replace the Faulty Part

Once you have determined which part of the toilet is at fault, you can move on to adjusting or replacing that part. If the float or fill valve is at fault, it is merely a matter of adjusting the height of this part—either by lowering the float if that is the problem or by raising the fill valve if it is underwater or missing the overflow tank when the toilet is flushed.

On the other hand, if the flapper is misaligned or if the chain is tangled or too short, you can realign it or fix the chain so that the flapper closes properly.

Finally, if the flapper is not sealing properly because it has deteriorated, you will need to replace the part.

Step 3: Call a Plumber If Nothing Else Helps

If you are unable to find the problem or are unsure as to how to properly fix the problem once identified, it may be best to call a plumber.

Be sure to check out the “Mistakes to Avoid, Tips & Tricks” section below so that you are not wasting money while waiting on the plumber to arrive!

Mistakes to Avoid, Tips & Tricks

Many problems with a toilet can be easily identified by flushing the toilet and watching how the parts work as the bowl is refilled. Once you know what is supposed to happen when a toilet is flushed, you will be able to clearly see an issue with one of the parts that is preventing the operation from being performed correctly.

It may be helpful to know what a properly working toilet looks like while flushing. If you have another toilet in your house, open the lid and flush that toilet while watching the process to see what happens. Compare this toilet’s operation to the faulty toilet’s operation: what is different? After identifying which part is at fault in the running toilet, you will be able to fix the problem by seeking the proper solution for that part.

In case you are fixing the problem yourself, be careful when adjusting any of the devices in your toilet. A ball float’s arm, for instance, is very easy to bend, so use care when moving it to test whether the float is the problem.

Finally, if your toilet is flooding over the bowl, you don’t have time to search for a solution right away, or you find that you have to call the plumber, your first resort should always be shutting off the flow of water entirely.

There is a shut-off valve—a small wheel on the pipe running from your toilet into the wall or floor—near the floor directly outside of your toilet. If you turn this valve, it will shut the water completely until you are able to deal with the problem.

Of course, you won’t be able to use this toilet once the water has been shut off.


A running toilet can be a hassle to deal with, but thankfully it is often something which you can fix yourself. Adhering to these simple steps will allow you to both find and fix your running toilet problem.

You might also want to read my article about how to deal with a toilet that runs randomly for a few seconds at a time.