How to Replace a Toilet Flapper

A worn flapper is a common cause of a toilet that periodically refills on its own. Replacement is usually simple because the work happens inside the tank rather than on pressurized plumbing connections.

Tools you will probably need

• usually none
• small adjustable pliers only if needed

Materials

• compatible toilet flapper

Project steps

1. Turn off the toilet supply valve and flush to empty most of the tank.
2. Disconnect the old flapper from its mounting ears and the lift chain.
3. Install the replacement and reconnect the chain with a small amount of slack.
4. Turn the water back on and flush several times, checking that the flapper closes cleanly.

Common mistakes

• Buying a flapper that does not match the flush valve size
• Leaving the chain so tight that the flapper cannot seal
• Leaving so much chain slack that it tangles

When to call someone

Call a plumber if the toilet leaks onto the floor, the tank or bowl is cracked, the shutoff valve does not work, or replacing the flapper does not solve the refill problem.

Project costs and times are rough planning estimates. Product instructions, local codes, home construction, and actual conditions take priority.