How to replace a toilet flapper

We'll replace the flapper in minutes so the toilet stops running.

What you'll need

At a glance

Turn off the water supply and flush to empty the tank before replacing the flapper.
Match the new flapper to the old one—universal flappers fit most toilets, but size and shape matter.
Unhook the flapper from the overflow tube ears and the chain; install the new one and reattach the chain.
Set the chain length so the flapper closes fully with minimal slack—too much slack causes incomplete flushes.
Test by flushing and adding food coloring to the tank; no color in the bowl means the seal is good.

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Goal: Replace the worn flapper so the toilet stops running.

Turn off the water supply at the shutoff valve. Flush to empty the tank. Sponge out remaining water.
Good: Tank is empty. Proceed to Remove the old flapper.
Bad: Water will not shut off—check the valve or call a plumber.

Goal: Take out the old flapper without damaging the overflow tube.

Unhook the chain from the flush lever. Pull the flapper off the overflow tube ears.
Set the old flapper aside to match the replacement.
Good: Drain opening is visible. Proceed to Match the new flapper.

Goal: Ensure the replacement fits your toilet.

Compare the new flapper to the old. Check diameter and shape. Universal flappers fit most two-inch drains.
Good: New flapper matches. Proceed to Install the new flapper.
Bad: Sizes differ—buy the correct replacement before continuing.

Goal: Seat the new flapper and attach the chain.

Slide the new flapper onto the overflow tube ears. Ensure it sits flat over the drain.
Attach the chain to the flush lever with minimal slack (about 1/2 inch).
Good: Flapper is centered and chain is correct. Proceed to Turn on water and test.

Goal: Restore water and verify the flapper seals.

Turn the shutoff valve counterclockwise. Let the tank fill. Flush and add food coloring to the tank.
Wait 5 minutes. No color in the bowl means the seal is good.
Good: No color transfer; running stops. Proceed to Verification.
Bad: Color appears in bowl—flapper may need adjustment or a different size.

Call a plumber if:

The shutoff valve will not turn or leaks when you turn it.
The new flapper does not seal after correct installation (may need a different model).
The tank leaks at the base (different problem—tank or gasket).

Reviewed by Blackbox Atlas

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