Reliable Plumbing’s Guide for How to Fix a Running Toilet
A running toilet is not only annoying but can also lead to higher water bills and wasted resources. Fortunately, fixing a running toilet is often a straightforward task that most homeowners can handle on their own. In this guide, we’ll walk you through the steps on how to fix a running toilet, offering simple DIY tips that can save you time and money before you need to call a professional plumber.
Understanding Why Your Toilet Runs
Before diving into the solutions, it’s important to understand the common reasons why your toilet might be running. The three most frequent causes are:

- Flapper Issues: The flapper is the rubber seal that controls the flow of water from the tank to the bowl. Over time, it can become worn or misshapen, leading to leaks.
- Fill Valve Problems: The fill valve controls the water level in the tank. If it’s not functioning properly, it can cause the water to continuously flow.
- Float Problems: The float rises with the water level in the tank and shuts off the fill valve when the water reaches a certain level. If it’s set too high or malfunctions, it can cause overflow.
How to Fix a Running Toilet: DIY Steps
1. Check the Flapper
The flapper is one of the most common culprits for how to fix a running toilet. Here’s how to check and fix it:

- Turn off the Water Supply: Locate the shut-off valve behind your toilet and turn it off to stop the water flow.
- Inspect the Flapper: Remove the tank lid and inspect the flapper. If it’s worn out or damaged, it needs to be replaced.
- Replace the Flapper: Flappers are inexpensive and available at any hardware store. Follow the instructions on the package to install the new flapper.
- Test the Fix: Turn the water supply back on and flush the toilet to see if the running has stopped.
2. Adjust or Replace the Fill Valve
If the flapper isn’t the issue, the fill valve might be the next thing to check:
- Turn off the Water Supply: As always, start by turning off the water.
- Adjust the Fill Valve: Look for the adjustment screw on the fill valve. Turn it to adjust the water level in the tank. The water should be about an inch below the top of the overflow tube.
- Replace the Fill Valve: If adjusting doesn’t work, you might need to replace the fill valve. Follow the manufacturer’s instructions for installation.
3. Fix the Float
The float controls the water level in the tank. Here’s how to adjust or fix it:

- Check the Float Position: The float should be set so that the water level is about an inch below the overflow tube.
- Adjust the Float Arm: If the float is too high, bend the float arm downwards. If it’s too low, bend it upwards.
- Replace the Float: If the float is damaged, you’ll need to replace it. Floats are also inexpensive and can be found at hardware stores.
Additional Tips
- Check for Leaks: Sometimes, a running toilet is due to a leak. Add a few drops of food coloring to the tank and wait 15 minutes. If the color appears in the bowl, you have a leak.
- Clean the Tank: Mineral buildup can affect the components in your toilet tank. Clean the inside of the tank to ensure everything works smoothly.
When to Call a Professional
If you’ve tried these DIY tips and your toilet is still running, it might be time to call in a professional plumber. Persistent issues can indicate more serious problems that require expert attention. Don’t hesitate to contact us at Reliable Plumbing and Heating for reliable and efficient plumbing services.