Is your toilet making that annoying sound of continuously running water? Don’t worry, you’re not alone! A running toilet can be both bothersome and wasteful. Luckily, there are simple steps you can take to fix the problem.

In this guide, we’ll show you how to stop a running toilet with easy-to-understand instructions. By following these straightforward steps, you’ll be able to put an end to that relentless running water and restore peace to your bathroom.

Understanding Your Toilet’s Working Mechanism

Toilet's Working Mechanism

To effectively troubleshoot and fix a running toilet, it’s essential to understand its working mechanism. Although toilets may vary in design, they generally operate on the same basic principles. Here’s a simplified breakdown of how a toilet works:


The tank is the upper part of the toilet that holds the water used for flushing. It is usually connected to the bowl by a large pipe called the flush valve.


The flapper is a rubber valve located at the bottom of the tank, covering the flush valve opening. When you flush the toilet, the flapper lifts which allows water to rush into the bowl and create the flush.

Fill Valve

After flushing, the tank needs to refill with water. The fill valve, also known as the ballcock or float valve, controls the water flow into the tank. It opens to allow water in and closes when the tank is full.


A float is a buoyant object attached to the fill valve. It rises as the water level in the tank increases. When the water reaches a certain level, the float lifts, signaling the fill valve to shut off the water flow.

Overflow Tube

The overflow tube is a vertical tube connected to the flush valve. It prevents the tank from overflowing by directing excess water into the bowl if the water level gets too high.

By familiarizing yourself with these key components and their functions, you’ll be better equipped to identify and resolve issues that cause a running toilet.

Common Causes Of A Running Toilet

Causes of a Running Toilet

A running toilet can be caused by various factors. Let’s explore 4 common culprits:

Problematic Flapper

The flapper is a rubber valve that seals the flush valve opening. If the flapper is worn, warped, or not properly aligned, it may not create a tight seal, causing water to continuously leak into the bowl.

Faulty Fill Valve

The fill valve controls the water flow into the tank. If it fails to shut off completely, water will continue to enter the tank, leading to a running toilet. This can occur due to a faulty valve mechanism or a worn-out seal.

Misadjusted Float

The float, typically a ball or cup-shaped object, regulates the fill valve’s operation. If the float is set too high, it can prevent the fill valve from closing, resulting in constant water flow. Conversely, if the float is set too low, the tank may not fill adequately after flushing.

Overflow Tube Issues

If the water level rises above the overflow tube, it indicates a problem. A damaged or improperly positioned overflow tube can lead to a running toilet.

Step-By-Step Guide To Fix A Running Toilet

Fix a Running Toilet

When it comes to how to stop a running toilet, there are some steps you can follow to fix the issue.

Tools And Materials Needed

  • Adjustable wrench
  • Screwdriver
  • Replacement flapper (if necessary)
  • Replacement fill valve (if necessary)
  • Teflon tape (if necessary)

Steps To Diagnose And Fix A Problematic Flapper

  • Lift the toilet tank lid and observe the flapper. Check for any visible signs of damage, warping, or debris.
  • If the flapper appears worn or damaged, turn off the water supply to the toilet by twisting the shut-off valve clockwise.
  • Disconnect the flapper from the flush valve chain or lift wire.
  • Install a new flapper by attaching it securely to the flush valve opening. Ensure it creates a tight seal.
  • Turn on the water supply and allow the tank to fill. Test the toilet by flushing it to see if the running has stopped.

Procedure For Adjusting Or Replacing The Fill Valve

replacing the fill valve

  • Turn off the water supply to the toilet.
  • Remove the tank lid and locate the fill valve.
  • Adjust the fill valve by either turning the adjustment screw or sliding the float up or down to set the desired water level.
  • If the fill valve is faulty and cannot be repaired, replace it with a new one following the manufacturer’s instructions.
  • Turn on the water supply and check if the toilet no longer runs.

Instructions On How To Adjust The Float

  • With the tank lid removed, observe the float attached to the fill valve.
  • If the water level is too high, gently bend the float arm downwards to lower the water level.
  • Conversely, if the water level is too low, gently bend the float arm upwards to raise the water level.
  • Flush the toilet and check if the water stops running at the desired level.

How To Address Overflow Tube Issues

  • Ensure the water level is approximately 1 inch below the top of the overflow tube.
  • If the water level is too high, adjust the fill valve to lower the water level.
  • If the water level is too low, check if the refill tube is properly attached to the overflow tube. Adjust or reconnect if necessary.
  • Inspect the overflow tube for any cracks or damage. If found, replace the overflow tube with a new one.
  • Test the toilet by flushing it to confirm that the running has ceased.

When To Call A Professional

Call a Professional

While many running toilet issues can be resolved through simple troubleshooting and repairs, there are situations where it’s best to seek the expertise of a professional plumber. Here are 5 instances when you should consider calling a professional:

Persistent Running

If you’ve attempted the basic troubleshooting steps and the toilet continues to run, it may indicate a more complex issue that requires professional diagnosis and repair.

Complex Repairs

Certain repairs, such as replacing the fill valve assembly or adjusting intricate internal mechanisms, may require the specialized knowledge and tools that a professional plumber possesses.

Limited Plumbing Experience

If you’re uncomfortable or inexperienced with plumbing repairs, it’s advisable to avoid potentially causing further damage. A professional plumber can handle the job safely and effectively.

Time Constraints

If you don’t have the time or patience to troubleshoot and fix the running toilet yourself, calling a professional can save you valuable time and effort.

Warranty Coverage

If your toilet or its components are still under warranty, attempting repairs yourself may void the warranty. Contacting a professional ensures that repairs are conducted properly and maintains warranty coverage.

Plumbing System Assessment

Plumbing system assessment

If you’re experiencing frequent or recurring issues with your toilet or suspect there may be underlying plumbing problems, a professional plumber can inspect your entire plumbing system to identify and address any issues.

Timely professional intervention is crucial to prevent further damage when dealing with a running toilet. Professionals can identify the root cause, prevent water damage, address underlying problems, ensure proper repairs, and preserve warranty coverage.

Their expertise and specialized tools enable efficient and effective resolution, saving you time, money, and potential complications.

How To Stop A Running Toilet: Conclusion

A running toilet can be a frustrating problem, but with the right knowledge and steps, you can stop it and restore normal functionality.

In this guide, we covered the common causes of a running toilet, the importance of understanding your toilet’s working mechanism, and a step-by-step guide to fix it.

While many running toilet issues can be resolved on your own, don’t hesitate to call a professional plumber if needed. Remember, a properly functioning toilet not only saves water and money but also ensures a peaceful and efficient bathroom experience.

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