A toilet tank flapper is a rubber seal that lets water flow from the tank into the bowl when you flush, then closes to refill the tank

When the flapper wears out or warps, water leaks constantly into the bowl, your water bill climbs, and the toilet runs between flushes. Replacing it costs between $5 and $15 for the part itself and takes about 15 minutes with basic tools — usually just a flathead screwdriver or your hands. You do not need a plumber for this repair.

The flapper sits at the bottom of the tank, attached to a chain or rod connected to the flush handle. When you push the handle, the chain lifts the flapper, water drains, and gravity closes it again. Over time — usually two to five years — the rubber degrades, cracks, or warps, and water seeps past the seal.

Key Takeaways

  • Turn off the water supply at the shutoff valve under the tank before you start, then flush to empty the tank completely.
  • The flapper is a rubber disc at the bottom center of the tank, held in place by a clip or two ears that fit over a pin.
  • Unhook the chain or rod from the flush handle lever, remove the old flapper, and slide the new one onto the pin in the same position.
  • Reattach the chain with just enough slack that the flapper closes fully — too tight and the tank won't refill, too loose and water leaks.
  • Turn the water back on and flush several times to confirm the tank fills and the water stops running.

What you need before you start

Gather a new flapper that matches your toilet model, a flathead screwdriver (optional — many flappers come off by hand), and a bucket or towel to catch any remaining water. Most hardware stores stock universal flappers that fit standard two-inch drain holes, but bring a photo of your old flapper or the model number from inside the tank lid if you want an exact match.

Locate the shutoff valve under the tank on the left or right side where the water line enters. It looks like a small knob or lever. You will turn this off first. If you cannot find it or it does not turn, know where the main water shutoff is for your house in case you need it.

Turn off the water and empty the tank

Turn the shutoff valve clockwise (or lever-style valves counterclockwise) until it stops. You should feel resistance — do not force it. Flush the toilet once. The tank will empty and the water will not refill because the supply is off.

If water remains in the tank, use a sponge or small cup to soak it out into a bucket. You need a dry tank to see what you are doing and to avoid water spilling when you remove the flapper.

Locate and remove the old flapper

Look at the bottom center of the tank. You will see a rubber disc (the flapper) sitting over a hole. It is held in place by a clip or by two small ears that fit over a vertical pin. The chain or rod from the flush handle connects to the top of the flapper.

If the flapper has a clip underneath, push or pry it gently to one side with a flathead screwdriver until the flapper slides out. If it has ears, straightforward lift the flapper straight up and off the pin — no tools needed. Set the old flapper aside.

Install the new flapper

Slide the new flapper onto the pin the same way the old one sat. If it has a clip, position the clip so it will hold the flapper centered over the hole. The flapper should sit flat and not rock side to side.

Look at the chain or rod attached to the flush handle. Unhook it from the old flapper's attachment point (usually a small loop at the top) and hook it to the new flapper. Leave about half an inch of slack in the chain when the handle is at rest — the flapper should close completely on its own without the chain pulling it down.

Test the flush and check for leaks

Turn the shutoff valve back on by turning it counterclockwise (or clockwise for lever-style). The tank will begin to refill. Listen for the water to stop running once the tank is full — this means the flapper is sealing properly.

Flush the toilet and watch the flapper lift as the tank drains. When you release the handle, the flapper should close when ready and the tank should refill without running water into the bowl. Flush two or three more times. If water continues to run into the bowl after the tank is full, the flapper is not sealing — check that it is centered over the hole and that the chain has the right amount of slack.

Adjust the chain if water still runs

If the tank refills but water leaks into the bowl, the chain is too tight and is holding the flapper slightly open. Unhook the chain from the flapper and move it one link higher on the handle lever, then hook it back. This gives the flapper more room to close.

If the handle feels stiff or does not return to rest, the chain is too loose. Move it one link lower. Test after each adjustment. The goal is a handle that returns smoothly and a flapper that closes completely the moment you release it.

Frequently Asked Questions

How do I know if my flapper is actually broken?

The most common sign is water running into the bowl between flushes — you will hear a faint hissing sound. Another sign is a water bill that climbs without explanation. You can also add food coloring to the tank and wait 15 minutes without flushing; if the color appears in the bowl, the flapper is leaking.

Can I reuse the old chain or do I need a new one?

The chain usually lasts longer than the flapper. Reuse it if it is not rusted, kinked, or broken. If it is corroded or stiff, replace it — a new chain costs a dollar or two and comes with most flapper kits.

What if the flapper won't stay on the pin?

The pin may be bent or the flapper ears may be cracked. If the pin is bent, you can sometimes straighten it gently with pliers. If the flapper ears are damaged, the flapper will not hold. Buy a new flapper — they are inexpensive and the old one is clearly worn out.

Do I need to turn off the water if I am just replacing the flapper?

Yes. Turning off the water prevents accidental flooding if something goes wrong and lets you work without water dripping. It takes 30 seconds and is worth the safety margin.

My new flapper is too big or too small for the hole — what do I do?

Flappers come in standard sizes for two-inch and three-inch drain holes. Measure the hole diameter or bring your old flapper to the store to match the size. A flapper that does not fit the hole will not seal, and water will leak no matter how tight the chain is.