How to Fix a Running Toilet in 5 Simple Steps

Paul Pogue
Written by Paul Pogue
Updated November 11, 2021
A woman holding down the toilet handle
Photo: Titykul_b / Adobe Stock

It’s time to cross “fix the toilet” off your to-do list

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Weak flush? Running water noises? Increased water bill? Chances are you have a running toilet—one of many common toilet problems that are usually easy to fix. 

Use this guide to learn how to repair a running toilet—and bring down those utility costs, too! 

Difficulty: Easy (2/5)

Fixing a running toilet is a relatively easy task. The more you know about how a toilet works, the easier this job will be to tackle on your own. However, if this is your first time ever attempting to fix a plumbing problem, this DIY might take a bit longer since you will be learning as you go. 

Total Project Time: 30 minutes—3 hours.

The more plumbing experience you have, the quicker you can get the job done.

Cost: $0-$20

The cost to repair your toilet will vary depending on the materials you need (a fill valve costs $8 to $10 and a flapper costs $5 to $10), your location, and whether you choose to hire a professional. Hiring a plumber costs $45 to $150 per hour.


  • Wrench

  • Bucket

  • Sponge


  • Food dye

  • New flapper (optional)

  • New fill valve (optional)

  • Diluted vinegar (optional)

  • Locking nut (optional)

Signs of a Running Toilet

A running toilet happens when your toilet is constantly moving water through it, even when it’s not in use. 

Aside from the obvious sound of running water, you can tell you have a running toilet issue if you’re experiencing the following:

  • Having to hold the handle down in order for the bowl to empty

  • Having to constantly jiggle the handle to get it to stop running

  • Toilet randomly flushes on its own

  • Leaking water on the sides of the toilet

Common Causes

This plumbing issue can be caused by one of three things: problems with the overflow pipe, the flush valve, or the fill valve. 

How to Fix a Running Toilet

A running toilet is a relatively easy issue to learn how to fix, even without plumbing experience. However, it’s also easy to make the situation worse if you aren’t careful. If you’re feeling uncomfortable tackling this yourself, don’t risk it. Hiring a professional plumber now may actually save you money in the long run. 

1. Pinpoint the Problem

How can you narrow down the culprit? The process is simple. Put a few drops of food dye into the tank (the back of the toilet, underneath the lid). 

Let it sit for about five minutes. If the dye moves into the bowl, the issue can be narrowed down to the flush valve. But, if the dye does not move into the bowl, it’s likely an issue with the fill valve. 

2. Turn Off the Water

To shut off water flow to the toilet, locate the shutoff valve. This is usually the valve behind the toilet attached to the pipe running through the wall. Turn the valve clockwise to shut it off. 

3. Test the Flapper

The flapper is part of the flush valve system. This system controls the flow of water by opening the flapper when the toilet is being flushed and closing the flapper after flushing. 

Inspect the flapper for signs of wear, tear, and debris build-up that may be keeping the flapper from fitting correctly inside the flush valve, potentially causing your toilet to run. 

If there is debris build-up, simply clean the flapper using diluted vinegar. If there is visible wear, however, you may need to replace the flapper. 

4. Check for a Leaky Fill Valve & Fix It

The fill valve controls the amount of water being brought to your toilet from your house’s water supply. If this valve is leaking, it is likely that water will continue to flow into the toilet without stopping. Thankfully, each toilet has an overflow tube that will redirect the excess water, preventing your toilet from overflowing. 

Check to see if a leaky fill valve is the culprit by lifting the tank lid and looking for debris and calcium build-up in the valves.

If you need to replace your fill valve and would like to install it yourself, follow these steps:

  • Collect a sponge, a wrench, and a bucket.

  • Empty the toilet tank by shutting off the water supply and flushing the toilet. Use your sponge to soak up any remaining water.

  • Install the new fill valve according to the manufacturer’s instructions.

  • Turn the water supply back on.

5. Test Flush

Once everything has been fixed and replaced, give it a test flush. Leave the tank open to make sure everything is filling and draining properly. After flushing, wait about 5 to 10 minutes to monitor for any phantom flushing or continuously running water. 

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