How to Replace a Toilet Flapper in 30 Minutes

Before removing the old flapper, reach down to the water shut-off valve behind or near the toilet. Turn it clockwise until it stops moving. Then, lift the tank lid on the back of the toilet and empty the tank by holding down the flush handle.

“Make sure you don’t set the tank lid on a raised surface that it could fall off of (common apprentice mistake!), like the edge of the sink or tub,” says Joseph Wood, Expert Review Board Member, Master Plumber, and Founder of Boston Standard Company. “We recommend you put the lid face down on a carpet.”

As you’re emptying the tank, watch the flapper, which is a piece of black or red rubber connected by a chain. If the chain is too long, it may get stuck between the flush valve and the flapper, allowing the water to run. Or if the flapper isn’t aligning with the flush valve, it can prevent itself from sealing, causing a constant running water sound. Sometimes, the flapper is just too old to hold a seal and needs to be replaced.

Handle old flappers gently because the rubber and plastic components can become brittle and break if you apply too much pressure. Start by unlinking the chain connected to the flapper, but you can leave the chain for now—you'll either connect it to the new flapper or remove it completely if the replacement part has a chain.

The flapper is connected via two small pegs on each side. Either snap the flapper off the pegs if it's plastic, or slide the flapper off if it's rubber.

Note the make and model of your toilet, then head to the home improvement store or order a flapper online. You could do this step first if you wish—especially if you only have one toilet in your home or apartment. You could also take the old flapper to the store to find the same or similar replacement part.

While there are different types of flappers, most flappers for home use will be made of rubber. Start by aligning the flapper with the small pegs and sliding or snapping it into place over the flush valve. If the new flapper includes a chain, unclip the old chain from the flush handle lever, which is a bar toward the top of the tank, and connect the new chain. Otherwise, clip the bottom of the old chain to the new flapper.

Once you’ve clipped the flapper to the old chain or connected a new chain to the flush handle lever, check the slack on the chain. It should have some give and not be too tight, but it also shouldn’t be too loose.

Leave the tank lid off and turn the water valve back on. Let the water fill the tank above the flush valve before pressing the flush handle. Flush a few times, ensuring the water refills the toilet bowl in about 30 seconds and the chain doesn’t get stuck in the flush valve. When you’re satisfied with your work, replace the lid on the tank.