Plumbing Repair

Troubleshooting: Toilet Randomly Runs


Troubleshooting: Toilet Randomly Runs

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If you've been plagued by the perplexing phenomenon of a toilet that randomly runs, you're not alone. It's an annoying issue, especially because it disturbs your tranquility and incrementally increases your water bill. Nonetheless, despite its ubiquitous nature and potential to drive one up the wall, understanding why your toilet randomly runs and knowing how to fix it isn't rocket science.

Why Does Your Toilet Randomly Run?

A toilet that runs intermittently usually indicates a problem with its inner workings. Here's a deeper dive into some of the leading causes of this peculiar problem.

Issue With the Fill Valve

The fill valve is responsible for refilling the tank after each flush. If it's malfunctioning, the toilet runs to compensate for the lost water.

Worn-out Flapper Seal

The flapper creates a seal within the tank. A worn-out or degraded flapper fails to create a water-tight seal, causing the toilet to run randomly.

A Faulty Float

The float rises with the water level in the tank and tells the inlet valve when to shut off the water. If the float is set too high or is broken, water continues to flow into the overflow tube, causing the toilet to run.

Ways to Fix a Toilet That Randomly Runs

While it's essential to understand the potential causes, it's equally important to know how you can resolve a toilet that randomly runs. Here are some actionable steps you can take to address this issue:

Adjust the Fill Valve

  • Start by turning off the water supply to the toilet and flush it to drain water from the tank.
  • Now, following the manufacturer's instructions, adjust the fill valve. You might need to bend the float arm if it's a ballcock-style fill valve.
  • Once adjusted, turn the water supply back on and test if the problem persists.

Replace the Flapper

  • Turn off the water supply valve and flush the toilet to empty the tank.
  • Unhook the old flapper from the base of the overflow tube and take it to a home center to buy a matching replacement.
  • Install the new flapper, reattach the chain, turn the water supply back on, and try flushing to see if the issue is resolved.

Fixing or Adjusting the Float

  • If the toilet continues to run, the issue could lie with the float. Start by adjusting the float to a lower level to limit the tank's water level.
  • If this doesn't work, consider replacing the entire float assembly. Similar to replacing the flapper, this involves turning off the water supply, emptying the tank, removing the old float assembly, and installing a new one.

Preventing a Toilet That Randomly Runs

Now that you've solved the issue with your randomly running toilet, it's crucial to prevent this problem from reoccurring in the future. Regularly inspecting the toilet's interior components and replacing them at the first sign of wear and tear can save a lot of hassle and ultimately prevent your toilet from running at undesired times.

Remember, 'prevention is better than cure'. By staying aware and acting proactively, you can ensure that the mystery of the randomly running toilet stays unraveled and under control, saving you from frustration, sleepless nights, and unwanted spikes in the water bill.

Frequently Asked Questions About a Toilet That Randomly Runs

What causes a toilet to start running randomly?

A couple of common problems could cause your toilet to start running randomly. They include a worn out flapper, a faulty fill valve, an improperly adjusted float, an overflow in the water tank, and even mineral build-up can cause a toilet to run when not in use.

How can I fix a toilet that randomly runs?

Fixing a toilet that runs randomly essentially involves identifying the root cause of the problem. Once you've pinpointed the cause, you usually can fix the problem yourself with some basic tools. If the flapper is the issue, replacing it can be a simple solution. If the fill valve is faulty, there are kits available at any home improvement store that can help you replace it with ease. In cases where the float needs adjustment, a simple twist or bend can solve the problem.

How much does it cost to fix a randomly running toilet?

The cost to fix a toilet that randomly runs largely depends on the exact problem that's causing the run. For example, replacing a flapper or a fill valve can cost between $10 and $20 for the parts. If you're doing it yourself, that might be the only cost. However, if you need to hire a plumber, you could be looking at anywhere from $50 to $200 per hour for labor.

Sounds coming from a randomly running toilet: Are they bad?

Sounds emanating from a randomly running toilet are not necessarily bad, but they usually indicate that there is a problem that needs to be addressed. For instance, a constant hissing noise could indicate that water is leaking from the fill valve, while a gurgling sound could mean that there is a blockage in the lines.

Clogs and randomly running toilets: Is there a connection?

Yes, clogs can oftentimes be a cause of randomly running toilets. For instance, a minor clog that alters the normal flow of water can cause the toilet tank to fill up slowly, which in turn might cause the toilet to run longer than it should.

Does a running toilet waste water?

Yes, a running toilet can waste an exorbitant amount of water. According to the US Geological Survey, a running toilet can waste up to 200 gallons of water per day. That's a lot of wasted water, and besides being bad for the environment, it can also noticeably increase your water bill.

Is a randomly running toilet bad for my plumbing system?

A randomly running toilet can indeed have detrimental effects on your plumbing system in the long term. Not only can it lead to an overworked septic system, but it might also increase the chances of leaks developing elsewhere in your plumbing due to increased pressure.

Can a randomly running toilet lead to a high water bill?

Since a continuously running toilet can waste up to 200 gallons of water in a day, it can definitely cause a spike in your water bills. It's hence crucial to address the issue as soon as you identify a constantly running toilet in your home.

Does temperature affect a toilet that randomly runs?

Temperature can, indeed, have an impact on a toilet that runs randomly. Changes in temperature can cause the components in your toilet tank to expand or contract, leading to leaks or misalignments that could cause your toilet to run unpredictably.

Cons of a Toilet Randomly Running

Despite the limited advantages, there are numerous, more consequential disadvantages associated with a randomly running toilet:

Waste of Water

  • One major disadvantage of a toilet that runs randomly is the wastage of water, which can add significantly to the water bill.
  • This water wastage is also environmentally unfriendly, especially in regions where water conservation measures are necessary.

Consistent Noise

  • The constant sound of water running can be a source of noise pollution in the home, interrupting peace and tranquility.
  • This noise can be particularly bothersome during quiet hours, like late at night or early in the morning.

Impact on Water Pressure

  • A toilet that randomly runs can also reduce the water pressure in other areas of your house.
  • This can be inconvenient especially when you need to use other water-consuming appliances.

Potential for Major Plumbing Issues

  • While a running toilet often indicates a simple issue, it can also be a sign of more complex problems in your plumbing system.
  • This could include issues with the sewer line or wastewater system, which are both labor-intensive and costly to fix.

Damage to Toilet Components

  • The consistent running of water can wear out the toilet components more quickly.
  • Replacement parts in addition to repair services may be required, leading to further cost.


One main thing we've established is that when a toilet randomly runs, it's usually a sign that some part of the toilet is malfunctioning. Typically, it's either an issue with the fill valve, the flapper, or the overflow tube. So, understanding the different parts of the toilet system can help in fixing the problem efficiently and maintaining it properly.

A toilet that randomly runs can be disturbing and costly. Recognizing the causes can help save water and reduce water bills. A malfunctioning flapper or a faulty fill valve can be the culprits. Swiftly exploring the issue and taking actions to fix it helps maintain the toilet in good working condition and prevents water waste.

Whether in fix-up endeavors or trying to diagnose the issue, it's crucial to find out why the toilet randomly runs. Constantly running or not, water wastage and an unexpected hike in the water bill are never a pleasant combination. A good knowledge of how a toilet works and the proper guide on troubleshooting can save time, money, stress, and, of course, water!

About KYPD Plumbing

Welcome to KYPD Plumbing! We're a locally-owned and operated plumbing company based in Nicholasville, Kentucky. With years of experience under our belt, we are committed to providing top-notch plumbing services to our valued customers. Our expert team takes pride in offering prompt, reliable, and professional services. We believe in doing the job right the first time and we go the extra mile to ensure your total satisfaction. Your plumbing problems are our business, and we love every minute of it!

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