That sound of a toilet running constantly long after it’s been flushed is more than just annoying; it’s a silent source of major water waste and a hike in your monthly utility bill. A running toilet can waste hundreds of gallons of water per day! Learn simple plumbing troubles and how to fix them.
At 1213 Plumbing, we know that most running toilet issues are caused by a few small, inexpensive parts in the tank that have failed. Here is a guide to the most common causes of a constantly running toilet and how you can fix them.
1. The Faulty Flapper (The Most Common Culprit)
The flapper is the rubber or plastic seal at the bottom of the tank that covers the flush valve opening. When you flush, the flapper lifts, allowing water to rush into the bowl. When the flush is complete, it should drop back down to create a watertight seal.
| Problem | Symptom | The Fix |
| Worn or Warped Flapper | Water constantly trickles into the bowl, and the tank keeps refilling itself every few minutes. | Replace the flapper. Rubber flappers degrade over time, losing their ability to seal. |
| Kinked or Tangled Chain | The chain connecting the flapper to the flush lever is either too short, too long, or caught under the flapper, preventing a full seal. | Adjust the chain length. There should be a small amount of slack (about 1/2 inch) when the flapper is seated. |
2. The High Water Level (Problems with the Float)
The float (or float cup) controls the height of the water in the tank and tells the fill valve when to shut off the water. If the water level is too high, water will spill directly into the overflow tube, causing the tank to constantly refill itself.
| Problem | Symptom | The Fix |
| Float Set Too High | The water level in the tank is above the top of the overflow tube. | Lower the float. Gently bend the float arm down (for older models) or turn the adjustment screw/clip on the fill valve mechanism until the water level is about 1 inch below the top of the overflow tube. |
| Faulty Fill Valve | Even with the float adjusted correctly, the water continues to rise and spill into the overflow tube. | Replace the fill valve. If the float mechanism is operating correctly but the valve won’t shut off, the entire fill valve assembly is likely worn out. |
3. The Failing Fill Valve (The Source of the Hiss)
The fill valve (or ballcock) is the part that refills the tank after you flush.
| Problem | Symptom | The Fix |
| Slow Leak/Hissing Sound | You hear a slight hissing or running sound even when the toilet hasn’t been flushed. This means the fill valve is allowing a slow trickle of water into the tank, likely due to a worn-out internal seal or diaphragm. | Replace the fill valve. While some parts can be replaced internally, replacing the entire fill valve assembly is the most reliable long-term solution. |
When to Call a Professional Plumber
While these problems are often DIY-friendly, you should call 1213 Plumbing if:
- You can’t determine the source of the leak after checking the flapper and float.
- The toilet has a cracked tank or bowl.
- The leak is coming from the base of the toilet, indicating a possible problem with the wax ring or flange.
- You need to replace the fill valve and are uncomfortable working with the water supply connections.
Don’t let a running toilet waste your money. A quick, simple repair can save you thousands of gallons of water annually. Contact your local experts at 1213 Plumbing today!