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Closeup view of a man's hand doing a repair on an open toilet tank.

How to Stop a Toilet from Running

A toilet that continually runs is enough to drive just about anyone crazy. The sound of constantly running water is an annoyance and can also cost you money on your water bill. Luckily, you can take a few DIY steps to fix a running toilet in your home. 

What To Do When Your Toilet Doesn’t Stop Running 

There are many possible causes of a running toilet. If your toilet keeps running, here are some steps you can take to troubleshoot and resolve the issue: 

  1. Remove the tank lid and diagnose the problem: Some of the most common problems that cause your toilet water to run continuously are issues related to the overflow tube, flapper, or fill valve.  

  1. Look for the overflow tube: This is usually located in the center of the tank and is made of PVC or metal, depending on your toilet brand. 

If toilet water keeps running out and over the overflow tube, the water level in your tank is too high. This causes the toilet to never realize when it’s full, so it won’t shut off, and the water will continue to run. 

Adjusting The Water Level in Your Toilet Tank 

How you adjust the water level in your toilet depends on the type of fill valve you have. If you have a valve connected to a floating rubber ball, you can bend the metal arm that the ball attaches to or shorten the chain that attaches the arm to the flush lever. This adjustment will prevent the water level from being too high.  

You can also adjust the water level in your toilet’s tank by using the adjustment screw (if your toilet model has one, it’s usually set off to the side of the fill valve). Try turning the screw in one direction and then test flush the toilet. Watch the tank refill to see if the water level rose or lowered and make further adjustments accordingly. It may take a few tries to get the water level just right. A few twists of the screw should make a noticeable difference in your water level. 

Related Topic: 3 Reasons Why Your Toilet Is Slow to Fill 

Fixing or Replacing the Flapper 

If you do not see issues with your water level, the next item to check is a part called the flapper. Your flapper is a flat piece of rubber located at the base of the toilet tank.  

If your flapper is bad or worn, it can cause water to continuously escape and leak, which leads to constantly running water. Look at the chain that connects the flapper to your fill valve. If there’s no slack in the chain, it may hold the flapper too high, causing an incomplete seal. You can adjust the chain so there is a little more slack, and the flapper can more easily reach the bottom of the tank and form a seal.  

If your chain isn’t the issue, try pressing on the flapper and listen for a few seconds. If your toilet stops running while you are pressing on the flapper, this means the flapper is worn and needs to be replaced.  

After turning off the water supply valve, you can easily disconnect the flapper from the fill valve and take it to a local home improvement store to ensure you get a matching replacement. Reconnect the new flapper the same way you disconnected the old one.  

If neither the water level nor the flapper was the issue, then the fill valve should be replaced. 

Overhead view of a toilet tank which has been cleaned from the inside. View of the float and fittings of the toilet drain mechanism.

Replacing the Fill Valve 

To replace the fill valve, follow these steps: 

  1. Shut off the water supply to the toilet and flush to empty the tank. 

  1. Unscrew the nut that holds the fill valve in place and pull out the old valve. 

  1. Reverse these steps to install the new fill valve. 

  1. Follow the directions that come with the new valve for your specific toilet model and know that you will have to reset the water level (see step two).   

If you believe you have solved the issue causing your toilet to run, give it a test flush. If the toilet keeps running after flushing, this means that there’s still a problem, and it’s best to consult a professional plumber. 

Can’t Stop Your Toilet from Running?  

A toilet that won’t stop running can be very annoying. If the running water sound isn't enough to keep you up at night, the thought of wasting water and higher water bills just might. A running toilet can waste up to 900 litres of water every day! If you don’t have the time or patience to fix your constantly running toilet, reach out to your local Mr. Rooter Plumbing for help. Call us at (855) 591-0128 or request a job estimate online today.