4 Reasons Why My Toilet Is Running (& How To Fix It)

Did your water bill suddenly become more expensive without having any leaks in your system? Maybe you wanted to be sure, so you inspected every pipe around your house. Unfortunately, you did not find any damages or leaks. You may need to pay attention to your toilet because it may be the root cause of the issue.


The most common reason a toilet is running is a flapper that isn’t working. When it happens, you need to go to Home Depot to get a new flapper to fix it. It really isn’t very hard!

In this article, we also go over the following topics:

  • The flapper we recommend you get
  • What an overflow tube is
  • How to change a flapper

Continue reading

Reasons a toilet is running

There are several causes for toilet running. However, the four ones below are the most common users encounter. You could experience one or many at a time, so we recommend having some awareness degree with each one. 

Cause 1 – Cracked toilet flappers

2-inch toilet flapper

A broken flapper causes it to run on and off for a few seconds. The flapper seals the tank as soon as ample water is inside it. A decaying or cracked flapper lets water flow inside it even if it is closed. In some cases, it is intermittently running.

A raised flapper lets water through the bowl. We recommend checking it periodically to prevent this issue from happening. It happens, so the best thing you can do is to replace the cracked flapper immediately.

The best place to look for a replacement is at a hardware store. To prevent inconvenience, we recommend knowing your toilet model. It may come in different sizes. 

Cause 2 – The chain got caught.

If replacing the flapper does not seem to fix the issue, you could look at the chain. A chain links the flush lever and the flap. Note that pulling the lever to flush lifts the flap. Issues with the chain could cause water to run continuously.

A common issue is a chain that is too long. The chain could get caught somewhere, preventing the flapper from sealing. On the other hand, a too short chain will not seal it at all. 

Cause 3 – The float needs to be lower.

Too much water in the tank causes it to overflow. If the float is too high, the water fills it up and pours into the overflow tube. Filling too high is not a good thing. 

To address this issue, you must lower the float so the tank will not overflow. 

Cause 4 – The refill tube needs repositioning.

If the refill tube is in an incorrect position or if the refill tube is too long, a running toilet will occur. It will cause the bowl to pump water inside of it. The valve creates a suction, pulling water out of the valve and pushing it into the toilet.

In instances like this, you must shorten or reposition the tube above the overflow’s opening. 

Toilet Overflow Tube

An overflow tube is a vertical tube located inside the tank, which you can find below the arch-shaped refill tube. Its job is to transfer water into the bowl if the ballcock breaks down. It stops or prevents the tank from overflowing.

The chain pulls the flush valve open when someone presses the flush lever. Water pours into the toilet bowl as soon as the valve opens. After a flush, the tank’s water level drops to a low level. The water quickly leaves, and the tank will start to fill again. While the tank refills, water from the fill valve flows through the refill tube and into the overflow tube.

The overflow tube drains the water.

The overflow tube’s primary responsibility is to drain the water into your toilet bowl. It works closest to the refill tube. The refill tube’s position should be above the overflow tube, not crammed inside. These two should barely have contact to function correctly.

The overflow tube is the biggest component in a toilet. Its functionality makes it one of the smartest pieces too. 

Mansfield toilet

Increasing bill

When it keeps running without pause, it will impact your consumption levels, causing your bill to increase. Moreover, you are also wasting tons of water. A running urinal should not be a reason to panic because it is easy to fix.

There are a few reasons for a running lavatory and some ways to check for it. As soon as you identify the cause, you can quickly remedy it. We will discuss everything in detail in the following sections. 

Toilet Running Every Few Minutes And Keeps Running Off And On

American standard toilet

You would understand if the lavatory runs after using it. However, if it randomly runs, there may be an issue here. If you have not used it for a long time, it should not run. Folks who believe in superstition may think of some paranormal activity happening. The real issue lies in the water tank.

Plumbing issues can occur randomly. These include shower temperature changes and leaks along the water system. After flushing, the water should stop running within a few seconds or one minute. If it does not or randomly goes off and on, you are facing an issue. Some people refer to it as phantom flush.

Lever lifts

There are a few things happening when flushing. The lever lifts the flap as soon as you push down the flush. The flap acts as a block so that water from the tank does not flow down the bowl. Water rushes down the bowl when the lever lifts the flap. It effectively flushes out everything into the drainage pipe system. The flap covers the tank once again after the entire process.

The toilet filling valve leverages a float to control it. It lets water flow through the tank after the flush. When the float rises into place, the water fills the tank, and the filling valve shuts off and prevents water from getting in.

Everything happens within a few seconds to less than a minute if there are no issues. The most common problems include the following:

  • The refilling tube needs repositioning.
  • The chain got caught.
  • There is a cracked toilet flapper.
  • The float needs lowering.

We will dive deeper into these problems in the following sections. 

Why Does My Toilet Keep Running And Will Not Stop Filling?

used toilet

A running lavatory wastes several water gallons, resulting in a higher bill. The first step you need to do is to verify if the water keeps running without filling the tank.

Turn off the toilet’s supply. You must find a knob on the back wall, typically behind it. Twist the knob to the right to turn it off. The next step is to remove the lid and identify the components inside. They all work together, so you should know how the entire system operates.

Toilet components

Look inside a toilet

Here is a list of all the components and how they work.

  1. Toilet Flush Lever – You will find the toilet flush lever outside the tank. It is usually silver in color. It connects to the flapper inside the tank.
  2. Rubber Flapper – The flapper blocks the water inside the tank from flowing into the bowl.
  3. Pump – The pump refills the tank after flushing.
  4. Float – The float lowers and raises depending on the water level. It serves as an indicator for the pump to stop.
  5. Overflow Tube Sets – The tube sets indicate where the water levels should be. 

How To Stop The Toilet From Running

There are several factors to consider for a running toilet. You can stop this from happening by following these simple do-it-yourself fixes. Fixing is a whole lot easier than you think. Beginners should not take more than one hour to do it.

Possible DIY repair

The fixes are straightforward, so do not get intimidated by the plumbing. You can even fix it while reading this section. The tools you will need are pliers and a hacksaw. In some cases, you will need replacement parts if something needs replacing.

Without further ado, let’s dig in!

Step 1: Test the flapper.

toilet flapper unboxed

An issue with your flapper may cause water to run off and on. We recommend following the below steps. 

  1. When you hear the water running inside the tank, use a stick to push down the flapper and wait for it to stop.
  2. If the water stops flowing, the flapper is not properly sealing, so change it.
  3. Make sure the fill tube is at least 0.5 inches shorter. You can do it by measuring its length across the surface.
  4. Turn off the supply valve underneath the toilet (or the main supply if the valve leaks) before replacing the flapper.
  5. After flushing the toilet to remove the majority of the water, remove the old flapper.
  6. Purchase a replacement flapper of a similar type and install it as directed on the packaging.
  7. Make sure there is some slack in the flapper chain when closed. You do this by attaching it to the lever arm.

Here are some flapper products we recommend purchasing as a replacement. 

Essential Values 3-Inch Toto Flapper Replacement

The Essential Values flapper is an excellent aftermarket Toto toilet replacement.

It uses high-quality rubber for an excellent seal. The chain uses stainless steel with a hook. It does not break or rust quickly, meaning you can use it for a long time without needing to replace it.

The universal fitting 3-inch flapper helps save water because of its security seal. It is also resistant to germs and chlorine. Moreover, it is also quick and easy to install. 


Rust-proofHigh-quality rubberLongevitySecurity seal


  • It does what it’s supposed to.
  • Easy to install
  • It corrects a problematic flapper.


  • It doesn’t install itself.
  • It will not fix the issue if the flapper is not the issue.
  • Make sure you get the right size
Replacement flapper
2,698 Reviews
Replacement flapper
It's a great pick.

Fluidmaster 504 2-Inch Universal Flapper

The Fluidmaster 504 has a universal design, allowing it to fit most toilets on the market. It works well on flush valves with or without mounting ears. The 504 is also chlorine-resistant, thanks to its Microban protection. 


Universal fitWorks on all flush valvesChlorine-resistant5 year- warranty Stainless steel chain


  • We like the price.
  • If it’s the size your toilet needs, it works great.
  • Easy to install.


  • Make sure a 2-inch flapper is what you need.
  • It doesn’t install itself.
Alternative flapper
2,498 Reviews
Alternative flapper
Here's another alternative.

Step 2: Check leaks on the fill valve.

fill valve

The fill valve can potentially leak. Here are the steps to take to confirm. 

  1. Look for a fill valve leak while flushing the toilet.
  2. While the tank is filling, lift up the toilet float arm to check if the water stops.
  3. Adjust the float lever to stop filling the water level when it is 0.5 to 1 inch below the overflow pipe’s top. 
  4. If there is leaking, replace the fill valve.

The following items are excellent replacement fill valves for your lavatory.

Korky 528MP QuietFILL Fill Valve

The Korky 528MP is a universal replacement for worn-down valves and ballcocks. It keeps your lavatory clean and running smoothly.

The twist-lock mechanism makes it a breeze to install. The set kit includes the following items:

  • Refill tube
  • Fill valve
  • Mounting nuts
  • Metal refill tube clip
  • Refill adjuster
  • Cone washer
  • Coupling nut
NameQuietFILL Platinum Fill Valve
Exterior FinishMetal
Item Dimensions LxWxH3.25 x 5.5 x 14 inches
Item Weight‎8 ounces
Made inUS


  • The price is great.
  • Fast delivery
  • It fits most toilets.
  • It’s made in the US.


  • It’s not a generally-known brand.
Fill valve
3,990 Reviews
Fill valve
Here's a fill valve.

Kohler GP1083167 Silent Fill Valve

The Kohler GP1083167 is an excellent fill valve replacement for all Kohler class five toilets. It has an adjustable height to accommodate different models. Do not use an abrasive material when cleaning the surface because it could damage it.


  • We love its silent operation.
  • Worth the extra money
  • Solid build
  • Not difficult to install


  • It may take a bit to arrive.
  • The instructions could have been better.
7,555 Reviews
Here's another fill valve from Kohler.

Step 3: Remove and replace the broken or old toilet fill valve,

  1. Turn off the water supply and flush the toilet. Use a sponge to remove any remaining water.
  2. Remove the water supply line, unscrew the locknut of the fill valve, and lift it out.

Step 4: Install the fill valve replacement

By this step, we assume you have a replacement part ready.

  1. As directed on the instruction page, install the replacement fill valve in the tank and tighten the locknut by half a turn.
  2. Check the overflow pipe’s height.
  3. If the overflow pipe is still higher than the critical level mark even after the fill valve is at the highest point, cut the overflow pipe shorter with a hacksaw.
  4. It should be one inch below the critical level mark.

Step 5: Connect the fill tube

The final step is connecting the fill tube.

  1. Connect the new fill tube’s end to the adapter included in the kit and the other one to the nipple.
  2. Fasten the angle adapter to the overflow pipe.
  3. Attach the flapper chain to the flush lever. This step finishes the installation process.
  4. Rotate the supply knob to allow water to fill the tank.
  5. Do a test flush of the toilet.
flapper tank ball

You should have addressed the issue of running water at this point. The frequently asked questions section below should quickly help you get any needed information. 


The following are the frequently asked questions of readers about the topic.

Why does my toilet keep running even after replacing the flapper?

Occasionally, replacing the flapper does not immediately solve the issue. The flush valve is pitted or rough if the toilet still runs. 

You can smoothen its edges to prevent water from running. If you can remedy the issue, we do not recommend replacing the flapper with a new one. 

What is the most common problem that occurs when the toilet won’t stop running?

The most common problem when the toilet does not stop running is overflowing water flowing down into the bowl. The water comes from the tank and flows through the overflow tube.

So you might ask when this happens? If the water in the tank is beyond the normal levels, it will overflow. To adjust the water level, adjust the float’s height. 

Is it hard to replace a toilet fill valve?

Replacing a fill valve does not need a lot of experience with plumbing. It also does not take a lot of one’s time. If you are looking for the most details, we recommend checking the HOWTO section above.

Remember that replacing a toilet valve requires having some tools on hand, such as pliers and hacksaws.

How much does a plumber charge to replace a toilet fill valve?

The annual cost for such repairs would range between $60 to $200 per job. It is already inclusive of labor costs and replacement parts.

How do I know if my toilet pump is broken?

There are a few ways of checking if your toilet pump needs repairing. The most common issues that require a pump replacement would include the following:
– Cracked flapper
– Tubes
– Overflow pipe
– Fill valve