How To Fix a Running Toilet

Running toilets can get annoying while wasting many gallons of water, leading to higher utility bills. Fortunately, fixing this plumbing issue is often a simple DIY task that most homeowners can manage with basic tools. In this segment, This Old House plumbing and heating contractor Richard Trethewey demonstrates how to diagnose and repair a running toilet. We’ll also explore other causes of a running toilet and provide step-by-step instructions to fix the problem in this guide.

Understanding the Anatomy of a Toilet

Before starting the repair process, familiarize yourself with the components of a toilet tank, including the fill valve, flapper, float, flush valve, and tank lever. These parts work together to create the flushing mechanism. 

When you push the tank lever, it lifts a chain connected to the flapper so the water rushes from the tank into the bowl. As the water level drops, the flapper closes, and the fill valve replenishes the tank until the float reaches the right height. Knowing how these components interact can make diagnosis and repair much easier.

Common Causes of a Running Toilet

Several factors can cause a running toilet, including the following:

• Corroded flush valve seat
• Cracked overflow tube
• Faulty flapper
• Malfunctioning fill valve
• Misaligned chain

Figuring out the specific cause will ensure you perform the correct repair. In many cases, the flapper or its associated components are the problem.

How To Diagnose a Running Toilet

By examining your toilet’s components, you can pinpoint the issue and proceed with the right repair. To determine whether the flapper is causing your toilet to run, follow these steps:

1. Remove the tank lid and set it aside carefully.
2. Flush the toilet and observe the components in action.
3. Check if the water continues to run after the tank has been refilled.
4. Listen for any unusual sounds, such as hissing or gurgling.
5. Inspect the flapper for signs of wear, damage, or discoloration.

Fixing a Faulty Toilet Flapper

A worn or damaged flapper is one of the most common causes of a running toilet and you can repair it yourself by following our instructions below.

Step 1: Inspect the Flapper

1. Turn off the water supply to the toilet using the shutoff valve.
2. Flush the toilet to drain the tank.
3. Unhook the chain from the flush lever.
4. Remove the flapper from the flush valve.
5. Examine the flapper for signs of wear, warping, or mineral buildup.

Step 2: Replace the Flapper

If the flapper shows signs of damage or deterioration, it’s best to replace it. The new flapper must be compatible with your specific toilet model to create a proper seal. Follow the steps below to replace the flapper:

1. Take the old flapper to a hardware store to find an exact match.
2. Clean the flush valve seat thoroughly.
3. Install the new flapper and check that it sits properly on the flush valve.
4. Reattach the chain, leaving a small amount of slack.
5. Turn the water supply back on and test the flush.

Adjusting the Chain and Float in the Toilet

Sometimes, the problem lies with the flapper’s associated components instead. In the video, Trethewey explains that an improperly positioned float on the chain can cause issues. You can fix this issue by adjusting the chain and float as follows:

Chain Adjustment

1. Check the chain length to see that it has a slight slack when the flapper is closed.
2. If the chain is too long, remove excess links or adjust the clip on the flush lever.
3. If the chain is too short, add a chain extension or adjust the clip to provide more length.

Float Adjustment

1. Locate the float on the chain, if present.
2. Position the float near the water line when the tank is full.
3. If there’s no float, consider removing it altogether to prevent it from interfering with the flapper as Trethewey demonstrates.

These chain and float adjustments can help fix your current issue and prevent future problems. You should regularly check these components as part of your routine maintenance.

Addressing Toilet Fill Valve Issues

If the flapper and chain are in good condition, the fill valve may be the issue. The fill valve controls the water level in the tank and plays an important role in the flushing mechanism. Here’s how to address problems that may stem from the fill valve:

Step 1: Clean the Fill Valve

1. Turn off the water supply and flush the toilet.
2. Remove the cap from the fill valve.
3. Hold a cup over the valve and turn on the water briefly to flush out debris.
4. Clean the valve components with a soft brush.
5. Reassemble the fill valve and test the flush.

Step 2: Replace the Fill Valve

If cleaning doesn’t solve the issue, you may need to replace the fill valve as follows:

1. Turn off the water supply and flush the toilet.
2. Disconnect the water supply line from the fill valve.
3. Unscrew the lock nut securing the fill valve to the tank.
4. Remove the old fill valve and install the new one according to the manufacturer’s instructions.
5. Reconnect the water supply and test the flush.
6. Adjust the fill valve to match the required water level if needed.

Checking for Other Issues in Your Toilet

If the above adjustments and repairs don’t fix your running toilet, you’ll need to check the rest of your toilet’s parts for problems. While less common, issues with the overflow tube or flush valve seat can also cause a running toilet. Here’s how to check whether these parts are the cause:

Overflow Tube Inspection

1. Check the overflow tube for cracks or damage.
2. Verify that the water level is about an inch below the top of the overflow tube.
3. Adjust the float or fill valve if necessary to maintain the proper water level.

Flush Valve Seat Examination

1. Drain the tank completely.
2. Inspect the flush valve seat for corrosion or damage.
3. Clean the seat with a scouring pad if you notice minor corrosion.
4. For severe damage, consider replacing the entire flush valve assembly.

Preventive Maintenance to Avoid a Running Toilet

To avoid future issues with a running toilet, consider carrying out the following preventive maintenance tasks:

• Avoid using harsh chemical cleaners that can affect your toilet’s rubber components.
• Clean your tank and its components annually to prevent mineral buildup.
• Promptly replace any worn-out components to prevent bigger issues.
• Regularly inspect the toilet components for signs of wear or damage.

Our Conclusion

Fixing your running toilet is a manageable DIY task that can save water and reduce utility costs. Regular maintenance and quick repairs can keep your toilet functioning efficiently to minimize potential problems. Remember to consult a professional plumber for more complex issues or if you’re unsure about any part of the repair process.