Why does my toilet randomly run for a few seconds?

The toilet is one of the most critical appliances in homes. As a result, you should fix any toilet issue with a lot of seriousness. One of the common questions asked in toilet forums is – why is my toilet randomly running for a few seconds?

A cracked toilet flapper, A leak in the fill valve, Excess or less water, a Poorly Installed Flapper Chain, and a bad toilet handle are the leading causes of randomly running toilets.

As plumbers call it, a running toilet, or “phantom flush,” is something you should deal with immediately. Not only is the sound irritating when it happens in the middle of the night, but it will also raise your water bill if you don’t correct the problem.

Why does my toilet randomly run for a few seconds?

How You Can Fix Your Randomly Running Toilet by Yourself

If you’re wondering why your toilet is flushing randomly after a few seconds, you’re in the right place. We will give you the answers and let you know what to do to rectify the problem. But before you begin, you need to turn off the water supply line.

Here’s why your toilet may be randomly running in the middle of the night:

A cracked toilet flapper

Why does my toilet randomly run for a few seconds?

One of the main culprits of a randomly running toilet is a damaged flapper. The flapper’s work is open to allow water to flow from the tank to the bowl when flushed and closed when the process is over to allow refilling. Therefore, if the flapper is outdated, damaged, or improperly seated, it will cause some water leakage from the tank to the bowl, leading to a phantom flush.

Hence, if the water cannot be kept in the tank, the flapper should be the first part that you examine.

A leak in the fill valve

Why does my toilet randomly run for a few seconds?

The second toilet part to consider is the fill valve. The toilet’s fill valve is responsible for refilling the toilet tank after flushing. As a result, a wrong or damaged fill valve will not close even after water fills to the required level. As a result, the toilet will have a leak that will flow into the toilet and cause random toilet running.

A faulty fill valve is even worse as the water will continue running and raise your water bill. Also, check the float and refill tube to see if it sticks in the right place. The refill tube should be placed on top of the overflow tube.

Poorly Installed Flapper Chain May Run Your Toilet Randomly

Why does my toilet randomly run for a few seconds?

After checking the flapper and fill valve, your next stop should be the flapper chain. A long or short flapper chain can also cause your toilet to flush randomly. The chain may sometimes be caught on one of the toilet parts, making it ineffective in performance.

Therefore, if the chain is short or long, it may affect how the flapper closes and seals the toilet, which will lead to random running.

Excess or less water

Why does my toilet randomly run for a few seconds?

There’s a reason why toilet manufacturers place a water line inside the toilet tank. For the toilet to work effectively, the tank’s water must be around the waterline. Most toilets require rest 1 or 2 inches below the fill valve. If water is above or below this line, an off-balance may cause the toilet to run randomly. So you need to adjust the water level properly to avoid this off-balance of water flow.

A bad toilet handle

Another overlooked reason may be a faulty handle. If the handle is not working correctly, it may cause water to continue flowing even after filling up. For instance, a damaged toilet handle may flush but fail to return to its original position. If this happens, the handle will allow more water to fill into the tank and overfill. As a result, the excess water will trickle into the bowl and initiate a phantom flush.

How to fix a randomly running toilet issue?

Tired of hearing irritating sounds in the middle of the night? Here are some fixes that you can perform to prevent a phantom flush from happening:  

  1. First, lift the lid off the toilet tank and put it on a soft cloth or rag. Note that it’s made of porcelain and is very delicate.
  2. Next, inspect the toilet and see if the water is on the water line or any other part that looks faulty.
  3. After identifying the part, shut off the water valve at the toilet’s back and flush to drain down the water from the tank.
  4. If the float ball is cracked, replace it with a new one. But if it’s loose, re-tighten it.
  5. In some cases, the ball float height may be lower or higher. Ensure that it’s at the recommended height.
  6. If the flapper is hardened, replace it with a new one. But if sediment prevents it from sealing correctly, get rid of the residue and test the flapper. It’s best if you change it to a new one.
  7. Monitor the fill valve and see if it has leaks. Replace a worn-out or damaged fill valve.
  8. If your toilet runs randomly, check the chain and ensure it’s not attached to anything. The chain shouldn’t be long or short. 

When should I call a professional plumber to fix your toilet from randomly running?  

Turn the water supply on and check if the problem is solved. If all the fixes discussed above don’t solve the problem or enough water leaks out, you should call a plumber to help you. However, a professional plumber will charge you several dollars, unlike when you fix it by yourself.

Besides, if you don’t have the knowledge or tools or are unsure about fixing the toilet, you should also call a professional plumber. You don’t want to make guesswork and end up worsening things.


A toilet can randomly run for a few seconds because of a cracked flapper, poorly installed flapper chain, a leakage in the toilet’s fill valve, a faulty toilet handle, or less/much water in the tank. No matter what’s causing your toilet to run randomly, you can still correct the problem.

Additionally, you should fix the running toilet issue as fast as possible before you end up paying an exorbitant water bill. Besides, fixing most problems is easy as long as you have the right tools. But if you’re unsure, it would be best to contact a professional plumber to help you. We hope you’ve found this article useful and fixed this randomly running toilet issue easily. For additional help, you can comment below.

Hi, this is Robert Crossan, the owner of this website, has 17 years of experience in the installation, maintenance, and repair of toilets and plumbing systems. After completing the Level 2 Basic Plumbing course in 2005, I started working in both domestic and commercial buildings as a professional plumber. So I can figure out the core difference between different toilet models and brands. It also helped me monitor their work performance and setbacks.


  1. Great article. I will still find out my problem if I don’t read your article. Toilet running occasionally gives me a headache. As soon as possible, I have to fix it on your own. Resolution should be applied without delay, especially if I am not always at home to check on my toilet.

  2. You can’t help but wonder: why does my toilet randomly run for a few seconds? A flushing mechanism is inside a toilet to send the waste to the sewer. Some of its components are flapper, chain, float and refill tube may cause this issue.

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