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Why Does My Toilet Keep Running?

Toilets have not changed much in the past decades. Toilets rely on a simple and effective system, but that does not mean that nothing ever goes wrong. One of the most common issues with a toilet is one that will not stop running. You flush the toilet, but it continues to run long after it should. What is going on?

Toilets usually keep running because the float is too high, the flapper is leaking, or the refill tube is too long. A toilet that keeps running can waste a lot of water and money. In some situations, you can fix it yourself, but often you will need to get help from a plumber to fix the issue.

If you notice that your toilet keeps running long past the normal flush cycle, you need to figure out what is wrong and whether you need to contact a plumber like the Sewer Surgeon. Keep reading to learn why your toilet is still running.

Why Does a Toilet Keep Running?

To understand why your toilet is still running, you first need to understand how your toilet stops running in the first place. What happens when you flush a toilet?

  • The flush handle opens the flapper at the bottom of the tank. This allows water from the tank to flow into the bowl.
  •  As the water level in the tank drops, the float also drops, which opens the fill valve. The flapper also drops back into place to stop water from leaving the tank.
  •  As the toilet bowl fills with water, gravity does the job and flushes the bowl.
  • The fill valve refills the toilet tank with water. As the water fills the tank, the overflow tub redirects excess water to the bowl to prevent overflowing, and the refill tube runs from the fill valve to the overflow tube to also refill the bowl.
  • Eventually, the tank fills enough that the float rises again and cuts off the fill valve.
  • The toilet is now ready to be flushed again.

The refilling of the tank is what people refer to as the toilet running. It should stop running when the tank is full.

There are a few different components that can go wrong which will keep your toilet running. If the tank does not fill, the toilet will keep running continually. The toilet can also run too long after each flush if the tank is having to fill more than it should to cut off the fill valve. So what causes these issues?

The Float Is Too High

The float is what turns the fill valve on and off. If the float is positioned too low, the fill valve shuts off too soon, resulting in a weak flush. But if the float is positioned too high, then the fill valve will take longer to cut off. This causes the toilet to run for too long.

In some cases, the float can be so high that it causes the toilet to run indefinitely. If the float is higher than the overflow tube, then water will continuously run as the water flows down the overflow tube and never fills the tank high enough to raise the float and cut off the valve.

Fixing this problem is relatively simple. You just need to move the float down, which will involve loosening and then retightening the float. If you are unfamiliar with the mechanics of a toilet, a plumber can make this repair quickly.

The Flapper Is Leaking

The flapper is the component that starts the flush by releasing water from the tank. When you push the flush handle, the flapper opens, but it should drop again, creating a water-tight seal to allow the tank to fill again.

If the flapper is not dropping fully or is leaking, then the tank will be losing water which will prevent it from filling enough to raise the float and shut off the fill valve.

There are two basic problems that can cause a leaking flapper:

  • The Flapper: It could be that the flapper is simply old and no longer creates a water-tight seal even when positioned correctly, which means it needs to be replaced.
  • The Flapper Chain: It is also possible that the flapper is fine but that the chain which raises and lowers the flapper may not be returning it to a sealed position after you flush. This is often because the chain is too long. Shortening the chain often solves the problem.

Sometimes the flapper gets caught temporarily, and simply jiggling it will cause your toilet to stop running. If this is happening often though, then it is probably time for a new flapper. You can buy a new flapper off the internet or at your local hardware store.

You can install the new flapper or shorten the chain yourself, but you may make it worse if you do not know what you are doing. Using a reliable service like The Sewer Surgeon will have your toilet fixed in no time and with very little hassle on your part.

Refill Tube Is Too Long

The refill tube is the tube that runs through the overflow tube to send water to refill the bowl after a flush. When the tank fills and the fill valve shuts off, the refill tube should also stop pulling water into the toilet bowl.

When the refill tube is too long and goes down into the overflow tube, it creates a suction that keeps pulling water and prevents the fill valve from shutting off. This can also happen if the refill tube is not positioned correctly in the overflow tube.

Typically this can be fixed by shortening the refill tube and clipping it to the overflow tube to keep it steady.

Are There Any Other Reasons My Toilet Is Running?

While these three reasons are the most common reasons for a running toilet, it is possible that the fill valve itself is broken.

In this case, you will likely need to completely replace the fill valve, which is a job best performed by a knowledgeable plumber like the Sewer Surgeon.

How Big of a Problem Is a Running Toilet?

Although a running toilet is often caused by a relatively minor issue, it is not a minor problem. A running toilet means that the fill valve is constantly running, which means it is pumping water constantly.

It may seem small, but a running toilet actually wastes significantly more water than a leaky faucet or shower. This can quickly add up to gallons and gallons of wasted water, and when you get your water bill, that will also equal lots of wasted money.

How Can I Tell If My Toilet Is Running?

A running toilet wastes a lot of water, and a large reason for this is that many people may not notice that their toilet is running. Sometimes the problem is a minor leak that does not make a lot of noise.

There are ways that you can check to see if your toilet is running without you being aware. Here is a quick check:

  •  Put a few drops of food dye in the toilet tank.
  •  Wait thirty minutes without flushing the toilet.
  •  Check the toilet bowl. If there is color in the bowl, then you have a running toilet.

If you notice that your toilet is making a sound from within the tank, that is another sound that the fill valve is still running. Removing the lid to check to see if you notice water movement in the tank is another simple way to check.


A constantly running toilet is a serious problem that adds a lot of money to your monthly water bill. Luckily the most common causes of a running toilet are a simple fix. With help from the Sewer Surgeon, you can have your toilet and your water bill back to normal.




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