A toilet that keeps running almost always has one of 3 problems: a flapper that isn't sealing, a fill valve that won't shut off, or a float set so high that water spills into the overflow tube. Lift the tank lid and look. These are inexpensive parts, and a running toilet can waste a lot of water.
Reviewed by Ron Olsen, Master Plumber, certified in Washington
Why a Toilet Keeps Running
- Worn or warped flapper
- Water leaks from the tank into the bowl, so the tank keeps refilling.
- Faulty fill valve
- The valve doesn't shut off when the tank is full.
- Float set too high
- The water level rises above the overflow tube and runs into the bowl.
- Tangled chain
- A chain that is too short or caught keeps the flapper from closing.
What You Can Safely Check
- Lift the tank lid and check whether water is flowing into the overflow tube.
- Adjust the float down so the water stops about an inch below the top of the overflow tube.
- Check the flapper chain. It should have a little slack.
- Add food coloring to the tank. If color reaches the bowl without flushing, replace the flapper.
- Close the shutoff valve behind the toilet if you can't stop the running.
When to Call a Plumber
Call a plumber if new parts don't stop the running, if the shutoff valve won't close or is leaking, or if the toilet also leaks at the base.
The repair is usually part of toilet repair, which explains what the plumber does and what affects the cost.
Running Toilet Questions
Is a running toilet urgent?
It isn't dangerous, but it wastes water and can raise your bill significantly. Fix it soon or close the shutoff valve until you can.
Why does my toilet refill by itself every so often?
This is called phantom flushing. It's usually a slow flapper leak letting water into the bowl.