How to Fix a Running Toilet: A Step-by-Step Guide

how to fix a running toilet
how to fix a running toilet: a step-by-step guide

Is your toilet running? Well, you better go catch it! But seriously, a running toilet is not only annoying but can also waste a lot of water and cost you money in the long run. Luckily, fixing a running toilet is often a simple DIY task that anyone can do. In this step-by-step guide, we’ll walk you through how to fix a running toilet, so you can end that constant sound of running water and start saving some cash. So, let’s get to it!

Identify the Problem

The first step in fixing a running toilet is to identify the problem. There are several reasons why a toilet might be running, including a faulty flapper valve, a defective fill valve, a leaky flush valve, or an issue with the water supply line.

Here’s how to troubleshoot each of these common problems:

  • Check the flapper valve: If your toilet is constantly running, it’s possible that the flapper valve is not sealing correctly. To check this, remove the tank lid and flush the toilet. Watch the flapper as the tank refills with water. If the flapper stays open, it likely needs to be replaced.
  • Inspect the fill valve: If the water level in the tank is too low or too high, the fill valve may be the culprit. Ensure that the tank’s water level is at the recommended level marked on the tank. If it’s not, adjust the fill valve accordingly.
  • Look for leaks: There may be a leaky flush valve if you hear water running but see no visible leaks. To check for this, add a few drops of food coloring to the tank and wait 15-20 minutes. If the water in the bowl changes color, it’s likely that there is a leaky flush valve that needs to be replaced.
  • Check the water supply line: If none of the above issues is the problem, there may be an issue with the water supply line. Ensure the water shut-off valve is fully open and the fill tube is correctly attached.

You can move forward with the appropriate repair steps by identifying the specific problem with your running toilet.

Gather the Necessary Tools and Supplies

Before you repair your running toilet, it’s vital to ensure you have all the necessary tools and supplies on hand.

Not having the right tools or parts can cause delays and frustration, so it’s best to be prepared.

Here are some reasons why it’s essential to gather all necessary tools and supplies:

  • Saves time: Having everything you need on hand means you won’t have to interrupt your repair to go out and buy missing parts or tools.
  • Ensures proper repair: Using the correct tools and parts for your specific toilet model and problem ensures that the repair is done correctly and will last.
  • Increases safety: Some repairs, such as working with water or electricity, can be dangerous without the proper tools or precautions.

Here’s a list of the necessary tools and supplies you’ll need to fix a running toilet:

  • Adjustable wrench
  • Screwdriver (flathead or Phillips, depending on the type of screws)
  • Replacement flapper valve (if needed)
  • Replacement fill valve (if required)
  • Replacement flush valve (if required)
  • Rubber gloves
  • Towel or rag

In addition to these essential tools and supplies, you may need some additional items depending on the type of toilet or a specific problem you’re experiencing.

For example, you may need a special dual-flush valve if you have a dual-flush toilet.

If your toilet is older or has unique parts, you may need to order specific replacement parts online.

Researching and ensuring you have everything you need before starting the repair is a good idea.

Turn off the Water Supply

Before beginning any repairs on your running toilet, it’s essential to turn off the water supply to prevent any flooding or water damage. Here’s how to do it:

Step 1: Locate the Shut-Off Valve

The shut-off valve is typically located on the wall behind the toilet.

There are two types of shut-off valves: a traditional valve with a round handle or a newer valve with a lever.

If you have an older toilet, the valve may need to be corroded or difficult to turn.

If this is the case, you may need pliers or a wrench to turn the valve.

Step 2: Turn off the Water Supply

Once you’ve located the shut-off valve, turn it clockwise to shut off the water supply.

Use pliers or a wrench if you can’t turn the valve by hand. Make sure the valve is fully closed.

Step 3: Flush the Toilet

Flush the toilet to remove as much water from the tank as possible.

This will make it easier to work on the inside of the tank without getting wet.

Step 4: Remove the Remaining Water

Use a towel or rag to soak up any remaining water in the tank or bowl. This will prevent any water from leaking out during the repair.

Following these steps, you can safely and effectively turn off the water supply to your running toilet.

Remove the Old Flapper Valve

The flapper valve regulates water flow from the tank to the bowl. If the flapper valve is damaged or worn out, it can cause a running toilet.

Here’s how to remove the old flapper valve:

Step 1: Remove the Tank Lid

Before beginning any repairs on the inside of the toilet tank, it’s essential to remove the tank lid to avoid accidentally breaking it.

Set the tank lid aside in a safe place.

Step 2: Identify the Flapper Valve

The flapper valve is a rubber or plastic component located at the bottom of the tank. It’s connected to the flush lever by a chain or plastic arm.

Step 3: Disconnect the Flapper Valve

Disconnect the flapper valve from the flush lever by unhooking the chain or sliding the plastic arm out of the slot.

Then, detach the flapper valve from the overflow tube by pulling it off the pegs.

Step 4: Remove the Flapper Valve

Remove the flapper valve from the tank by pulling it off the flush valve seat.

If the flapper valve is corroded or stuck, you may need to use a pair of pliers to twist and loosen it gently.

Step 5: Troubleshoot Common Problems

If the bolts holding the flapper valve in place are rusted or corroded, you may need to use a penetrating oil such as WD-40 to loosen them.

If the flush valve seat is damaged or corroded, you may need to replace it with the flapper valve.

Following these steps, you’ll be able to safely remove the old flapper valve and troubleshoot any common problems that may arise during the process.

Install the New Flapper Valve

Before installing the new flapper valve, selecting the right one for your toilet is essential.

There are many different types of flapper valves on the market, so choosing one compatible with your toilet and its specific requirements is necessary.

To install the new flapper valve, follow these steps:

  1. Remove the new flapper valve from its packaging and inspect it for damage or defects. Make sure that it’s the correct size and type for your toilet.
  2. Locate the mounting holes on the bottom of the new flapper valve. These holes will attach the flapper valve to the flush valve assembly.
  3. Align the mounting holes on the new flapper valve with the mounting holes on the flush valve assembly.
  4. Secure the new flapper valve to the flush valve assembly using the included mounting hardware. Tighten the bolts securely, but be careful not to over-tighten and damage the plastic components.
  5. Attach the chain to the new flapper valve using the included clip or hook. Make sure the chain is tight enough, and adjust it as necessary.
  6. Test the new flapper valve by turning the water supply back on and flushing the toilet. Check for leaks or other issues, and make any necessary adjustments.

Following these steps, you should be able to successfully install a new flapper valve in your toilet and fix any running or leaking problems.

Remember to choose a high-quality flapper valve designed for your specific toilet, and adequately align and secure the new valve to ensure proper functioning.

Turn the Water Supply Back On

Once the new flapper valve is installed, it’s time to turn the water supply back on and check for leaks.

Here’s how to do it:

  1. Locate the water shut-off valve and turn it back on by turning the valve counterclockwise.
  2. Allow the tank to refill with water.
  3. Check for leaks around the flapper valve and other parts of the toilet. If you notice any leaks, turn the water supply back off and check for any loose connections or other issues before turning it back on again.
  4. Check the water level in the tank. If it’s too high or too low, adjust the water level by adjusting the float valve. The float valve is typically located on the fill tube and can be adjusted by turning a screw or sliding the valve up or down.

Once you’ve turned the water supply back on and checked for leaks and the proper water level, you can flush the toilet a few times to ensure everything works properly.

Suppose everything seems to be in order; congratulations! You’ve successfully fixed your running toilet.

Test the Toilet

After completing the installation, it’s crucial to test the toilet to ensure it’s no longer running and functioning correctly. Here’s how:

  1. Turn the water supply back on and allow the tank to fill with water.
  2. Once the tank is full, flush the toilet and observe the flapper valve during the flushing process.
  3. The repair is likely successful if the flapper valve closes properly and the tank refills without issues.
  4. If the toilet is still running, there may be an issue with the flapper valve installation or another toilet component.
  5. Troubleshoot any issues during testing by referring back to the previous sections and ensuring that all components are correctly installed and adjusted.

It’s also essential to check for any additional problems that may arise during testing.

For example, weak flushing or incomplete filling may indicate an issue with the water pressure or another toilet component.

If any additional problems arise, refer to the previous sections and troubleshoot accordingly.


Fixing a running toilet may seem daunting, but it is straightforward. Following the step-by-step guide in this article, you can quickly identify and fix the problem without needing a plumber.