Replace a Toilet Flapper
The flapper is the rubber seal at the bottom of the tank — it wears out every 3–5 years and is the #1 cause of running toilets. A $5 part and 10 minutes solves it.
Tools
- ✓For drips and to set the tank lid on
- ✓For sopping the last bit of water out of the tank
Materials
- +2-inch is standard on older toilets, 3-inch on most high-efficiency toilets made since ~2005. Korky and Fluidmaster universal kits cover most. Bring the old flapper to the hardware store if you can.
- +Most flappers come with one; replace if the old chain is corroded.
Steps
-
1
Confirm the flapper is bad
Drop 5 drops of food coloring in the tank. Wait 15 minutes without flushing. If color seeps into the bowl, the flapper is leaking — replace it.
-
2
Shut off water and drain the tank
Close the supply valve, flush once to drain. Sponge out the last inch from the bottom.
-
3
Photograph the old flapper before removing
Snap a photo showing chain length and how it hooks onto the flush arm. Reinstall reference.
Tip: If your tank is unusually shaped, take a photo of the whole tank interior so you have orientation reference. -
4
Pop off the old flapper
Unhook the chain from the flush handle arm. Slip the flapper ears off the small pegs on either side of the overflow tube.
-
5
Install the new flapper
Slide the new flapper onto the same pegs. Reconnect the chain to the flush arm with about 1/2 inch of slack — too tight and the flapper won't seat; too loose and the flush is weak.
-
6
Turn water back on and test
Open the supply valve. Once the tank fills, flush 2–3 times. Watch the flapper seat fully between flushes. Listen for hissing — silence means it's sealing right.
Tip: If it still runs after 5 minutes, the fill valve (the tall white part) likely also needs replacement — same toolset, 20 more minutes.