Toilet Randomly Runs or Flushes Itself [Causes and How to Fix]

A common issue with toilets is that they can randomly run independently or flush themselves. What’s the problem when your toilet randomly runs?

If your toilet runs randomly and cuts on and off by itself, it has a phantom flush problem. A slow leak of water may cause random flushing from the tank into the bowl. One of the most common causes of this problem is a defective flapper or bad flush gasket. 

A good flapper will prevent any leaking of water from the tank into the toilet bowl. Its function is to re-seal the tank when a sufficient amount of water has gone through. However, when there’s even a slight crack in it due to decay, the flapper will allow water to continue flowing through. As a result, the toilet will run intermittently.

Read on to learn more about toilets that run randomly, the causes of this problem, and how to fix this issue.

Toilet Randomly Runs

toilet randomly runs

A toilet that runs periodically is experiencing a problem that plumbers call a phantom flush. An indication of this problem is a slow leak of water from the tank into the bowl. One possible cause is a broken flapper or a damaged flush seat.

The flapper seals the tank when enough water has gone through. However, a cracked or broken flapper will allow water from the tank to flow through continually. The result is random on and off of the toilet.

If the toilet randomly runs for a few seconds of the interval, it could also be that the water level in the tank is set too high. The water level in the tank may go over the limit and cause the toilet to run. This is why toilet manufacturers recommend maintaining the water level in the tank one inch below the overflow tube.

Phantom Flush Described

Once you push the handle on the tank, flushing starts. So, when nobody has pushed down the handle and the toilet flushed, that is phantom flush. Something started the flushing process. But don’t be afraid, there’s no ghost!

The extent of this problem will depend on how bad the tank is leaking. In some instances, you can hear the tank refill or the flushing toilet periodically. The reason this is happening is that the water level in the tank has dipped so low.

When this happens, it will cause the float ball to trigger the opening of the fill valve. If the leak in the tank is very fast, it may fill that siphon up with water. This will cause the running of a complete flush cycle.

Basics of Toilet Flushing

To better understand the problem of random flushing, you have to know the basics of how a toilet works. Firstly, in a toilet, there is a bowl where water stays. The tank is where all the mechanisms are. As you know, it is also where the water for flushing is.

Once you flush the toilet, a chain attached to the handle pulls up the flapper covering or seals a hole at the bottom of the tank. Then, the water flows down into a siphon tube underneath the toilet bowl.

As soon as that siphon tube fills up, it sucks the water out of the bowl until it is empty of water. This is why there is that distinctive sucking sound that you hear when you flush the toilet. When there is no more water in the tank, and the toilet bowl, the fill valve in the tank starts to refill the water inside the tank. At the same time, water also flows down into the toilet bowl.

A lever attached to the fill valve has a float ball or rubber balloon at its end. This floating ball contains air, so it will always float on top of the water. The refilling of the water tank continues until it reaches the level wherein the float causes the flipping of the fill valve to shut. That completes the flushing process.

For this process to be completed each time the toilet is flushed, the flapper has to stop the water from leaking while the water is being refilled in the tank. So, if the flapper is cracked or broken, random running of the toilet will result.

Why Is Phantom Flushing a Problem?

Now that you know that phantom flushing is not caused by anything paranormal, you may be wondering if this is really an issue. It is an issue if you consider that this problem, if not corrected, will cost you hundreds of dollars in water bills.

These are volumes of water that will literally go down the drain, and not even a single ounce of it you weren’t able to use. A study revealed that every flush of a toilet consumes about 1 1/2 gallons of water. That much volume of water is going down the drain every time your toilet flushes by itself.

Slow leaks on your toilet are even more insidious. Don’t you know that a continuous and steady leak can send 200 gallons of water down the drain each day? If you think paying an extra $200 for your water bill each month for water that you didn’t use is a waste of money, then you should definitely consider phantom flushing an issue.    

When money is hard to come by, wasting money on unused water should not be an option. You need to fix this problem because it eventually leads to the loss of money.

Causes of Flapper Problems

toilet randomly runs for a few seconds

While flapper problems are the common cause of toilets that randomly runs, there are different situations where the flapper is the main culprit. Here are some of the usual situations:

Bad Flapper

The most common cause of your toilet running randomly is a bad flapper. It could be already old, worn out, or cracked. During the close of the flushing cycle, it is supposed to drop down and seal the hole of the tank.

The problem with a broken flapper is that, yes, it still drops down the hole and seals it, but not completely. Due to the cracks on the flapper, water is allowed to go through steadily and continuously. This will result in the toilet running intermittently.

Float Is Too High

If the volume of water is too much for the tank to hold, the toilet could also run randomly. This will happen if the ball float or rubber float is set too high. It will cause the water to fill up and then pour inside the overflow tube. You need to lower the vertical level of the float to correct this problem.

Most toilet manufacturers indicate the top water level inside their tanks. Some indicate this in the installation guide that comes with the toilet when you buy it. Follow this recommendation so you will not experience phantom flushing.

The Chain Is Entangled

The handle outside the tank is connected to a chain connected to the flapper inside the tank. If you lift this handle, the chain will cause the flapper to lift and allow water in the tank to flow into the toilet bowl.

If this chain is caught anywhere in the inside parts of the water tank, you could experience intermittent flushing. The chain can get caught under the flapper and prevent it from fully sealing the hole. If the chain is short, it can also prevent the flapper from fully sealing the hole.

The Position of the Refill Tube Is Not Correct

If the refill tube inside the tank is not positioned properly or too long, random flushing can also occur. This will cause the continuous refilling of water inside the tank. The tube should be positioned just above the overflow opening. If it is too long, you should make it short.

How to Fix Toilet Randomly Running (Phantom Flushing)

There are several easy solutions that you can use to fix a toilet that runs intermittently. Try these solutions first before calling for a plumber. If the problem remains after doing these fixes, that’s the time you need to call for help:

Replace the Flapper

This is the easiest way, and you don’t need a plumber to do it. Here are the simple steps you need to follow:

  • If you find that the flapper is cracked or damaged, buy a new one and replace the broken one with it.
  • Close the intake valve that supplies water to the tank.
  • Then drain out the water inside the tank by flushing it.
  • Unhook the broken flapper from the chain and remove it from the tank.
  • Dry the inside of the tank and remove all the dirt and debris, especially those that lie near and inside the flapper hole.
  • Hook the new flapper to the chain and place it in the hole.
  • Adjust the length of the chain so that it will be the same length as before.
  • Open the intake valve and let water flow inside the tank until it is full.
  • Observe the tank as it fills up and check if there is any leak coming from the hole and the flapper.
  • Once the tank is full, close its lid.
  • Then, pull the handle to start the flush cycle. If the problem is fixed, you won’t be experiencing any more phantom flushing.
  • Try flushing the toilet several times to be sure.

Additional Tips That Can Help Fix Your Toilet That Randomly Flushes

toilet randomly flushes
  1. Adjust the height of the float. If the float is not high enough, the fill valve will not close. This will cause the toilet to run randomly.
  2. You can adjust the float’s height for toilets that use ball floats connected to the end of a metal arm by screwing it in or out to get the right height.
  3. Meanwhile, for those with set screws at the end of the arm, adjust the set screw. There is a spring clip on the side for modern floats that rise vertically through a metal tube. Slide this clip up or down to get the right height of the float.
  4. Lengthen or shorten the chain as necessary. This chain is used to lift the flapper from the hole. A flapper with the proper length will have an easy way of sealing the hole completely as the water in the tank is being refilled. If the chain is too tight, the flapper may not completely seal the hole.
  5. But if there is so much slack in the chain, you will have a hard time pulling off the handle to start the flushing cycle. The chain needs to have a 1/2 inch of slack in the middle.
  6. You can adjust the length of the chain if you will unhook it from the handle and then re-hook it onto the next higher link. Keep on adjusting the length until you get the right slack.  

Avoiding Random Running of the Toilet

The best way to avoid the random flushing of your toilet is to regularly inspect the conditions of the inside parts of the water tank. By doing this, you will be able to see what part is already wearing down. You can replace them before they can cause trouble.

This simple measure will help you prevent the development of more difficult problems that may need a professional plumber to fix. Most of the time, these plumbing repairs are costly. Regular cleaning of the inside parts of the tank will also help in avoiding phantom flush.

Conclusion: Toilet Randomly Runs for a Few Seconds

A toilet that intermittently runs or cuts on and off by itself is experiencing a problem called a phantom flush. The random flushing may be due to a slow leak of water from the tank into the bowl. The usual cause of this problem is a bad flapper seat or a defective flapper.

If the problem is caused by a bad flapper, just replacing it will easily solve the problem. However, if you have already replaced the flapper, adjusted the chain, etc., and the problem persists, you need the help of a qualified plumber to examine the real cause and to do the necessary repairs.