Worn flapper
A flapper that does not seal lets tank water leak into the bowl.
Plumbing troubleshooting
Running Toilet: Causes and Simple Checks
A continuously running toilet can waste water. Most common causes are inside the tank, where the flapper, chain, and fill valve control flow.
Common causes
Chain or handle problem
A chain that is too short can keep the flapper open.
Fill valve or float
If the water rises above the overflow tube, the fill valve may need adjustment or replacement.
Safe checks you can make
- Lift the tank lid and see whether water enters the overflow tube.
- Check that the chain has a little slack and the flapper closes fully.
- Turn off the toilet supply valve if the tank overflows.
When to call a professional
Call a plumber if the toilet leaks outside the tank, the shutoff does not work, or replacing tank parts does not solve it.
Explore other plumbing problems
This guide is general information, not a diagnosis. If water is near electricity, avoid the area and get immediate professional help.