A toilet flapper is the rubber seal that lets water drain from the tank into the bowl, and you can replace it yourself with no special tools
The flapper is a rubber disc attached to a chain inside your toilet tank. When you flush, the chain lifts it, water rushes down, and then the flapper falls back to seal the tank again. Over time—usually two to five years—the rubber cracks or warps, and water leaks slowly into the bowl. You'll notice the toilet running on its own or the water level dropping in the tank.
Replacing it takes about 15 minutes and costs $5 to $15 for the flapper itself. You do not need a plumber, and you do not need to turn off the water if you work carefully. The hardest part is usually just getting the old one off.
Key Takeaways
- Turn off the water at the shutoff valve behind the toilet, flush to empty the tank, and remove the old flapper by unclipping it from the overflow tube.
- Bring the old flapper to the hardware store or take a photo so you buy the exact same model—flappers are not universal.
- Slide the new flapper onto the overflow tube, attach the chain to the flush lever, and adjust the chain so it has about a quarter-inch of slack when the flapper is closed.
- Test by flushing several times and listening for water running into the bowl after the tank refills—if you hear it, the flapper is not sealing.
Turn off the water and empty the tank
Locate the shutoff valve on the water line behind the toilet, usually a small knob or lever near the base of the tank. Turn it clockwise (or flip the lever perpendicular to the pipe) until it stops. Then flush the toilet once to empty the tank completely.
If you cannot find the shutoff valve or it will not turn, you can still replace the flapper—just work slowly and keep a towel nearby. The tank will not drain on its own, but you can bail out most of the water with a cup before you start.
Remove the old flapper
Lift the toilet tank lid and set it somewhere safe where it will not break. Look inside the tank. You will see a rubber disc (the flapper) hanging from a chain attached to the flush lever on the left side of the tank. The flapper sits on top of a hollow tube called the overflow tube, which runs up the center of the tank.
The flapper is held in place by two small clips or ears on either side that hook onto the overflow tube. Pinch or pry these clips gently with your fingers or a flathead screwdriver, and slide the flapper up and off the tube. Unhook the chain from the flush lever by unclipping the S-hook or removing the clip that holds it.
Buy the correct replacement flapper
Flappers are not one-size-fits-all. Different tank designs use different flappers, and installing the wrong one will not seal properly. Take the old flapper with you to the hardware store, or take a clear photo showing the shape and any markings on it.
Show it to a staff member in the plumbing section and say "I need a replacement for this flapper." They will match it to the right part. If you order online, search for your toilet's brand and model number (usually stamped on the tank), then search "[brand] [model] flapper replacement."
Install the new flapper
Slide the new flapper onto the overflow tube so the two clips or ears hook onto the tube on either side, just as the old one did. It should sit flat and centered. The chain should hang loose below it.
Attach the chain to the flush lever using the S-hook or clip that came with the new flapper, or reuse the one from the old chain. The chain should have a small amount of slack—about a quarter-inch—when the flapper is resting closed. If the chain is too tight, the flapper will not seal all the way. If it is too loose, the flapper will not lift high enough to let water drain. Adjust by moving the S-hook up or down the lever arm or by removing a link if the chain is too long.
Test the new flapper
Turn the shutoff valve back on by turning it counterclockwise (or flipping the lever parallel to the pipe). The tank will refill. Once it stops, flush the toilet and listen carefully. You should hear water rushing into the bowl during the flush, then silence as the tank refills. Once refilling is complete, you should hear nothing—no water trickling into the bowl.
Flush two or three more times and listen each time. If you hear water running into the bowl after the tank has refilled, the flapper is not sealing. This usually means the chain is too tight, or the flapper is not sitting flat on the tube. Adjust the chain slack and test again. If the problem continues, the new flapper may be the wrong model—take it back and bring the old one to confirm the match.
Replace the tank lid and you are done
Once the toilet is sealing and refilling normally, carefully set the tank lid back in place. Do not force it—it should sit naturally on the rim. If it rocks or feels unstable, lift it off and reseat it.
Run the toilet a few more times over the next hour to make sure everything is working. A properly sealed flapper will stop the running-toilet sound and bring your water bill back to normal.
Frequently Asked Questions
What if the chain keeps getting tangled or the flapper does not lift all the way?
The chain is too long or has too much slack. Remove one or two links by unclipping the S-hook and moving it up one or two holes on the lever arm. The flapper should lift smoothly without the chain going slack. Test by flushing and watching the flapper rise inside the tank.
Can I replace the flapper without turning off the water?
Yes, but it is messier. If the shutoff valve is stuck or missing, bail out most of the tank water with a cup, then work quickly. Keep a towel and bucket nearby. The process is the same—just expect some water on the floor.
How do I know if the problem is the flapper and not something else?
Listen for water trickling into the bowl after the tank finishes refilling. If you hear it, the flapper is leaking. If the toilet runs but you do not hear water in the bowl, the problem is usually the fill valve, not the flapper, and you should call a plumber.
Do I need to replace the chain too?
Usually no. The chain lasts much longer than the flapper. Reuse the old chain unless it is rusty, kinked, or broken. If it is damaged, most new flappers come with a new chain, or you can buy one separately for a few dollars.
What if the new flapper leaks right away?
Check that the flapper is sitting flat and centered on the overflow tube—it should not be tilted or twisted. Verify the chain has the right amount of slack. If both are correct and it still leaks, the flapper may be the wrong model. Take it back to the store with the old flapper and ask them to double-check the match.