How to fix a running toilet
Most running toilets come down to two things: a worn flapper leaking water into the bowl, or a fill valve set so high that water spills into the overflow tube. Lift the tank lid and look. Adjust the float down if water is over the tube, or shut off the supply and swap the flapper if the bowl keeps refilling.
About 25 minutes to learnEveryday skill
Mark it once you can do it without this page open.
How to do it
- Take the tank lid off and set it somewhere flat where it cannot fall; it breaks easily.
- Check the water level: if it runs into the open overflow tube, lower the float by turning its adjustment screw or sliding its clip down.
- If the level is fine, add a few drops of food coloring to the tank and wait 15 minutes without flushing.
- If color shows in the bowl, the flapper is leaking; turn the shutoff valve behind the toilet clockwise and flush to empty the tank.
- Unhook the flapper's chain and slide its side ears off the pegs on the overflow tube.
- Take the old flapper to the store or read the tank label, and buy one the same size.
- Fit the new flapper, hook the chain with about a half inch of slack, turn the water back on and test.
Common mistakes
- Leaving the chain so tight the flapper cannot close, or so loose it catches under the flapper.
- Buying the wrong flapper size; two-inch and three-inch drains are both common.
- Forcing a stuck shutoff valve until it breaks.
- Ignoring a toilet that refills by itself every so often.
Quick self-check
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Teach this to someone
A one-page sheet for showing a friend, a roommate or a kid: what to say, what to show, and one question to check it landed.
Teach: How to fix a running toilet
What to say
Most running toilets come down to two things: a worn flapper leaking water into the bowl, or a fill valve set so high that water spills into the overflow tube. Lift the tank lid and look. Adjust the float down if water is over the tube, or shut off the supply and swap the flapper if the bowl keeps refilling.
What to show, in order
- Take the tank lid off and set it somewhere flat where it cannot fall; it breaks easily.
- Check the water level: if it runs into the open overflow tube, lower the float by turning its adjustment screw or sliding its clip down.
- If the level is fine, add a few drops of food coloring to the tank and wait 15 minutes without flushing.
- If color shows in the bowl, the flapper is leaking; turn the shutoff valve behind the toilet clockwise and flush to empty the tank.
- Unhook the flapper's chain and slide its side ears off the pegs on the overflow tube.
- Take the old flapper to the store or read the tank label, and buy one the same size.
- Fit the new flapper, hook the chain with about a half inch of slack, turn the water back on and test.
The check question
Ask: Water keeps trickling into the overflow tube. What do you adjust?
Related skills
- How to unclog a toilet
- Where is my main water shutoff
- How to fix a dripping faucet
- Every skill in Home Fixes
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Last reviewed . First published .