Why Does My Toilet Randomly Run For a Few Seconds?

One of the biggest problems I found last month at my home was a running toilet. Although it might seem like a minor inconvenience in the start, but a running toilet can be very annoying thing to manage.

Even though many of us think that running toilet is something very minor and can be ignored, it can become a very expensive obstacle if not fixed right away. I was initially confused because I couldn’t find the answer to “Why does my toilet randomly run for a few seconds”

However, I have recorded my experience with identifying and fixing a running toilet here. Hopefully, this will not only save you a lot of time in identifying the defect in your toilet but also help you with many easy solutions to fixing the toilet.

How Does a Toilet Work?

Toilet Flushing Mechanisms

Before we dive into the identification of a running toilet and its solution, It’s important for us to understand how a toilet works. Regardless of the make or the model, toilets flush mechanism operate similarly in all cases.

Start with emptying your toilet tank; a few flushes should do the job here. Even if it has phantom flush. Once the tank is empty, the toilet tank’s various parts will become visible to you. The toilet flush is connected to a chain that gets propelled up when the toilet is being flushed.

This action, in turn, raises a flapper connected to the other end of the chain, which lets the water escape. When dormant, this flapper blocks a gap in the tank that prevents the water from getting out. You will see a weird ball-like structure afloat on the water. This part helps the valve in letting the water in case the tank gets empty.

Furthermore, it works as a signal in preventing water from entering when the tanks’ capacity is met. The core of the tank contains an overflow tube. In the case of the water level peaking, the water gets drained by the toilet bowl.

Causes and solutions if your toilet randomly runs

Running Toilet CausesRunning Toilet Solutions
Flapper seal misplacementAdjust flapper seal
Miscalculation in the length of the flapper chainChecking connectivity between handle and chain
Leaky refill tubeInspecting the refill tube
Damaged handleFix or replace the toilet handle
Weakened gasketFix or replace the gasket
Cracked toilet flapperFix or replace the toilet flapper
Excess toilet float heightAdjust toilet float height
Sediment in toilet flapperClean toilet flapper and tank
Defective flushing mechanismReplace or fix the flush valve
Defective sensorFix or replace the sensor
Wrong water levelAdjust water level in the tank

Why Your Toilet Might Not Stop Running (Causes)

There are many reasons why a toilet might run constantly. Below is a list of the more common problems that might cause a toilet to run frequently:

1. Flapper Seal Misplacement

The flapper is very important in preventing water leakage. It’s significant to letting the water escape in times of flushing and stopping the water from leaking when the toilet is not being used.

If the water cannot be stored in the tank, then it is worth assuming that the flapper is probably misplaced. And if the flapper doesn’t seal flushes properly, then it can make the toilet start running. This valve gets typically dislodged due to prolonged use.

2. Miscalculation in the Length of the Flapper Chain

The flapper chain is vital since it is the primary component to trigger the entire flushing process. Its function helps the tank to be filled with fresh water and allow the existing water to escape as well. A short valve chain might not close the flapper properly, resulting in a running toilet.

3. Leaky Refill Tube

The refill tube links the toilet with a water source. It helps bring in water after the toilet is flushed. It is found on top of the water surface. If the position of the refill tube is off, then it can cause a running toilet.

4. Damaged Handle

The toilet handle is the trigger to the entire flushing process. It helps in exerting pressure into the flush tank, which in turn releases the water. During dormancy, it also helps in keeping the other components in check to prevent water leakage.

If the toilet handle gets damaged or has a faulty toilet handle in any way, it will certainly trigger a failure in the components, which will cause a running toilet.

5. Weakened Gasket

The gasket is attached to the very bottom of the toilet tank. It plays a vital role in determining when water should be released and when it should be contained. If it’s not changed over a long time, it will get damaged and cause water to seep out. This oversight will result in a running toilet.

6. Cracked Toilet Flapper

A broken toilet flapper could be the biggest reason for a running toilet. Due to constant interaction with the chemicals in the toilet tank, flappers tend to weaken over time. As a result, it can cause the flapper to decay and eventually collapse the whole process. If you found your toilet flapper is crumbled or cracked, that’s enough to result in a running toilet.

7. Excess Toilet Float Height

The float height measures how much water to fill up in the toilet tank. If the float height is higher than its ideal level, toilets can overflow or run intermittently. The standard height should be 1 to 2 inches down the fill valve and the overflow tube. Inappropriate height may cause an imbalance in the water level and a running toilet.

8. Sediment in Toilet Flapper

When you are using a toilet flapper for so long, it slowly allows sediments to get stuck on it. As sediments are fully covered inside toilet tanks including flappers, you will notice a noisy flush in every refill. Sediment slowly damaged your toilet flapper which can cause a leaking and running toilet.

9. Defective Flushing Mechanism

If you found any of the toilet flushing mechanisms are not working properly, you might be experiencing a running toilet. You must check all the available flushing mechanisms of your toilet including, Valve washer, retaining nut, float ball, float rod, inlet valve, inlet tube, piston, siphon, cistern, and everything

10. Defective Sensor

High-tech toilets have multiple automated sensors for cleaning and flushing. If one of the sensors is not running properly or defective, then you might be experiencing your toilet randomly running for a few seconds.

11. Wrong Water Level

An important cause why your toilet runs randomly is the wrong water level inside the tank. There is minimum and maximum water level that needs to be reached inside the tank, below which the tank won’t flush and above which will cause the tank to leak.
Sometimes if the flapper gets jammed due to sediment or the chain becomes too long, the water level also rises. You need to check the water level inside the tank and see whether it is in the correct position.

Easy Ways to Stop a Running Toilet (Solutions)

Now that you’ve checked the possible causes of your toilet running, it is time to explain the solutions in terms of those specific causes.

But know that, any fix related to the toilet needs to start with flushing the toilet and emptying the tank at first. Before that, you also need to turn off the water supply. As, running toilet repair cost is not so much, let’s continue with the solutions…

1. Adjust Flapper Seal

As we’ve already seen that one of the most common causes of running toilets is misplacement or damage of the flapper seal. If you notice the problem here then you need to adjust it.

Adjusting the flapper seal starts with fixing the lift wire. If you notice it bent, straighten it with your hands.

Now, loosen the guide arm adjustment screw. You can use your slip-joint pliers for that task. Adjusting this guide arm back and forth helps the flapper guide directly to the flush valve outlet. Re-tighten this guide arm.

2. Checking Connectivity Between Handle and Chain

Having a short-chain prevents the flapper from completely closing down, which results in a running toilet. However, if the chain is too long, then flushing won’t be possible at all.

The string should be connected to the handle at a length that will ensure enough space when the flapper is closing. Have the extra chain removed and have some space not to have the chain twisted into a knot. Replacing the lid of the tank, see if the flush rod hits the top. If it does, then bend the rod and readjust the chain.

3. Inspecting the Refill Tube

As mentioned earlier, a lot of components can be the reason behind a running toilet. Start off by inspecting the refill tube. If the water in the tank is not in contact with the refill pipe, reconnect it to the filling valve. Press down hard on the parts to connect them strongly.

The refill tube needs to be at least an inch high of the overflow tube. Pressing the handle should let you know if the water is going towards the refill tubes or not.

4. Fix or Replace the Toilet Handle

If you’ve found out that the toilet handle has been broken, you have to replace it with a new one. You can easily buy a handle in the store if you know the model and type of the toilet.

Sometimes, the handle is just stuck in a position. In that case, you won’t need to replace it. Just try releasing it, and it will be good to go.

5. Fix or Replace the Gasket

When you’ve totally drained the tank, locate two screws on the bottom. After unscrewing them, remove the rubber gasket from the tank’s outlet. You can clean and screw it back on if that works. However, after a long time of usage, the gasket usually gets corroded or torn.

You need to take the gasket to the nearby store to buy an exact sized one. Fit it onto the knob on the bottom with the tapered side facing away from the tank. Press in the gasket and re-tighten those screws in place.

6. Fix or Replace the Toilet Flapper

We spoke about adjusting the toilet flapper. However, if it is broken or cracked, you need to get it replaced by removing the old one from the tank. First, unhook the chain from the flush handle lever. Sip the side ears of the flapper from the pegs. These pegs usually extend from the sides of the flush valve tube.

Take the new flapper and put it into place by hooking each ear onto the pegs. Connect the chain you unhooked onto the handle level. Adjust the chain in a relaxed position with a bit of slack.

7. Adjust Toilet Float Height

As we’ve seen that the ideal water level is one or two inches below the fill valve, you can see a thin line on the inside wall of the tank marking that line. You need to maintain that water level, which means the flow should allow the water to fill up to that mark.

If you find the float too high, the water will go over the overflow tube, resulting in leakage. So, you need to lower it with the help of a flathead screwdriver. Loosen or tighten the bolt holding the ballcock to maintain the required level. Usually, turning the screw clockwise lowers the float and vice versa.

8. Clean Toilet Flapper and Tank

Sometimes, sediment can gather inside the tank when it has been used for long. If such sediment has fully covered the flapper, it will get damaged and cause water to run randomly. So, cleaning the flapper properly is the solution.

Remove the chain connecting the flapper and the handle and pull out the flapper. Using a brush or a scrub pad, clean the flapper as much as you can. Using vinegar or other chemical cleaner works like a charm as well.

9. Replace or Fix the Flush Valve

After you’ve drained the tank, disconnect its water supply tube, the flapper chain, and the refill tube at the top of the overflow pipe. Now, unscrew the bolts underneath the tank that hold the tank to the bowl.

When you lift off the tank, you’ll find the flush valve screwed with a locknut. Using a plumber’s wrench, remove the old flush valve. Install the new flush valve following the process mentioned previously.

10. Fix or Replace the Sensor

If your toilet is an automatic one, it has a sensor that flushes the toilet intermittently. Recalibrating it makes it flush only when it is needed. This fixing is necessary to avoid water wastage and save money in the long run.

11. Adjust the Water Level in the Tank

When the water level goes beyond the fixed measure, it causes the fill valve to activate for some moments before it reaches the right level. You need to loosen or tighten the float to manage the water level inside.

You can also clean the flapper and fix the chain length to adjust the water level inside the tank as well.

Wrap Up

And there you have it! No more reason to have the question “Why does my toilet randomly run for a few seconds” do cartwheels around your head. Not only will you be able to identify the reason behind a running toilet, but you’ll also be able to fix it quickly and save your water bill!

Hello, I'm Jon C. Brown, an expert in the field of toilets. With over 15 years of experience in this industry, a significant portion of my life has been devoted to crafting high-quality toilets and bathrooms. Consequently, I've received countless inquiries about the toilet and bathroom industries. That's why, I've launched this website to provide top-notch solutions for all your toilet and bathroom related needs.

3 thoughts on “Why Does My Toilet Randomly Run For a Few Seconds?”

  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. New toilet models are designed to save water with a minimum of 1.6 gallons per flush based on the mandate of EPA or 1.28 GPL with recent advanced models. Unfortunately, it’s not always possible, especially if your toilet keeps running off and on.

  3. 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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