5 Star Plumbing | How to Fix a Toilet That Randomly Runs: DIY Guide
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How to Fix a Toilet That Randomly Runs: DIY Guide

5 Star Plumbing > Blog > How to Fix a Toilet That Randomly Runs: DIY Guide

Homeowners who are willing to do their own repairs often enjoy the satisfaction of working on a project themselves and saving money at the same time. While it may be a good idea to paint or hang shelves around your house, doing plumbing work yourself can be very dangerous.

Because plumbing is a complex field that requires expertise and extensive training to perform, we always recommend hiring a professional. For learners who are not deterred by this warning, we will discuss all the fundamentals that every beginner should learn to avoid causing harm.

Why Does My Toilet Randomly Run?

There are many plumbing issues that can affect a toilet, such as leaks or changes to water temperature in your shower.

When you flush a toilet, the water usually stops flowing after a few seconds. So if your toilet keeps running randomly on and off, then you know that something is wrong with it. This is sometimes referred to as “phantom flushing.” When you phantom flush the toilet, it’s like a chain reaction. You pull up on the lever to lift the flap that covers the water inlets (tubes). This allows pressurized water from the attached toilet tank or cistern to flow through another channel into your bowl.

When the flap opens, all of the water rushes down to fill up and flush out the bowl; when it closes again, only air remains in the tank. The float, which is connected to the toilet filling flush valve and placed in the toilet tank, controls when enough water has returned into it after you flush. When that happens—and not before—the toilet-filling flush valve shuts off.

The entire process usually takes less than a minute if everything goes according to plan. If a toilet randomly runs for a few seconds and then stops without flushing, it might be caused by one of several problems: either the float has become disconnected from its chain or loose in its housing (and is not making proper contact with the water flowing into the tank), or there’s foreign matter inside blocking the holes that allow air to enter.

The water filter refill tube may need to be repositioned

A randomly running toilet can occur when the refill tube is too long or positioned improperly, causing water to enter the bowl at an unnatural rate.

If this is happening, the tube that connects the refill flush valve to your toilet tank should be shortened or repositioned so it pokes just above—but does not go into—the opening of your overflow.

The toilet flapper may be broken

If a randomly running toilet keeps running for a few seconds at a time, it is probably because the flapper needs to be replaced. A defective or crumbling flapper will allow water to continuously flow in and out of the toilet tank without shutting off properly when enough fluid has passed through.

When the flapper is raised, it allows water from the toilet tank to flow into the bowl.

Chain Might Be Caught

If you have tried replacing the flapper, it may be that your chain is caught. When you pull up on the lever to flush and lift up the flap, there’s a mechanism attached (a chain) which makes this happen. Issues with chains can result in continuous toilet running occasionally. If, for example, the chain is too long or is hanging on the wrong link, it can catch under the flapper and prevent a proper seal. If it’s too short, it won’t make contact at all.

Float Must be Lowered

If too much water is allowed to enter the toilet tank, it can overflow into the bowl. This occurs when the float level has risen sufficiently that water flows over and into the overflow tube attached to—but separate from—the flush pipe. This can cause a phantom flush.

If you have a randomly running toilet, reducing the amount of water in the tank might solve the problem.

How to Fix a Toilet That Randomly Runs: Step-By-Step Guide

If your toilet randomly runs —whether constantly or intermittently—there’s a good chance that it isn’t functioning correctly. Although there are many possible causes, this symptom is often called a randomly running toilet.

There are several reasons why a toilet occasionally runs. The most obvious one is that the flapper isn’t closing properly, but there could also be other problems with the fill valve or overflow pipe line.

1. Check the Length of the Flush Chain

The chain should hang from the lever in a nearly straight line and connect to the flapper. At both ends, you will see one hook that goes through holes on either side of the lever and another for attaching itself—via more holes—to something else (e.g., a metal rod).

If the chain is too long, it may form a kink that prevents the flapper from seating properly after flushing. To correct this problem, lengthen or shorten the chain by slipping another link onto (or off of) its hook at one end.

To adjust the slack in the chain, make sure it is long enough to allow the flapper to close completely but not so long that it droops when closed. You may have to bend the links with needlenose pliers.

2. Check the Toilet Flapper

If your toilet continues to run after this, consider the flapper. Also be sure that water flows through—if not, adjust the hoses accordingly, or exchange them for new ones. Lastly, make sure the overflow pipe is at the right height.

3. Check the Toilet Tank Float Valve

To start, check the fill valve. If it’s off, this can make your toilet to run occasionally. Check for the float ball (the thingy that goes up and down with the water level) inside —if it’s loose, try tightening down its nut to see if it fixes the problem (it probably will).

When In Doubt, Call the Pros!

Professional plumber John C. Flood, who services the Northern Virginia, Washington D.C., and Maryland areas, can resolve any issue with your toilet or other plumbing fixtures—and he’ll do it at a price you can afford!


What Tools Do I Need to Fix a Running Toilet?

It is possible to borrow some of the tools you will need from a hardware store or plumbing supply shop, but an adjustable wrench, pliers and screwdrivers are good items for your toolbox. A plunger and toilet auger (snake) should also be on hand in case they’re needed.

What Happens if a Toilet Runs All Night?

If a toilet randomly runs all night, it will waste water and increase your water bill. Excess water can potentially flood your septic tank, leading to failure and saturation of the drain field in extreme cases.

Does Phantom Flushing Raise the Water Bill?

A phantom flush occurs when your toilet keeps flushing without anyone being there. This is usually caused by problems with the fill valve or flapper. If you have a phantom flushing problem, it is possible that you could be wasting as much as 200 gallons of water per day! The answer is definitely YES — this pesky problem does waste water and increase your bill.

How Long Does a Toilet Flapper Last?

A toilet flapper should be replaced every 4 to 5 years. Old or worn-out toilet flappers can cause leaks in the plumbing system that may cause damage to your home.

Mike Joshua

Mike Joshua, a 33-year-old plumber based in California. With a passion for solving complex problems and a commitment to his trade, Mike has dedicated the past 8 years of his life to honing his skills as a professional plumber. After completing technical college Mike quickly secured a job in a plumbing company and has been working steadily ever since. Mike's experience includes not only households but industrial gas and plumbing systems and installation, repair the equipment for different types of business He is known for his attention to detail, strong work ethic, and ability to complete projects on time and within budget. He is always striving to improve his skills and stay up-to-date with the latest industry developments and advancements. In conclusion, Mike enjoys outdoor activities such as hiking and camping. He also has a passion for DIY projects around the home and is always looking for new challenges to tackle.

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