What Is a Flapper?
A flapper is a rubber or plastic seal inside a toilet tank that covers the flush valve opening. Pressing the toilet handle lifts the flapper and lets tank water enter the bowl. After the flush, the flapper should settle back onto the opening and stop water from flowing.
Quick Facts About Flapper
Category
Toilet tank component
Used for
Controlling flush water
Common confusion
Often confused with the fill valve
Also called
Flush Valve Flapper, Toilet Flapper
Often discussed with
Toilet Repair
Key Takeaways About Flapper
- The flapper seals the flush valve opening.
- A worn flapper can cause a running toilet.
- A flapper is not the fill valve.
How Flapper Works
A flapper seals the flush valve opening at the bottom of a toilet tank. The toilet handle connects to a lift chain or rod. When you press the handle, that connection raises the flapper and releases tank water into the bowl.
Related glossary terms: Fill Valve, Toilet Wax Ring, Shutoff Valve.
After the flush, the flapper drops back into place. The seal should sit evenly on the flush valve seat. A damaged, stiff, loose, or poorly fitted flapper may let water pass after the flush. The fill valve then runs more often as it tries to refill the tank.
Toilet designs vary, so the replacement must match the flush valve and chain setup. Some toilets use a canister seal instead of a traditional hinged flapper.
Expert Note
When we inspect a toilet, we check the flapper’s seal, hinge, chain, and contact with the flush valve seat. We also watch the tank after flushing, because a slow leak may not be obvious while the toilet is in use.
Flapper in Practice: A Real-World Example
A toilet that refills on its own may have a flapper that no longer seals the flush valve opening. A plumber may inspect the flapper and chain, then fit a compatible replacement if needed.
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Related Terms
Fill Valve
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Toilet Wax Ring
A Toilet Wax Ring is a flexible sealing gasket that sits between a toilet base and…
Shutoff Valve
A Shutoff Valve is a plumbing control that stops or allows water flow through a pipe…
Water Pressure Gauge
A water pressure gauge is a testing tool that shows the force of water inside a…
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