Toilet flapper — seat it evenly with no twist in the chain

A new toilet flapper can still leave the toilet keeps running if the flapper chain is twisted and holds one edge off the flush valve seat. Untwist the chain and let the flapper drop flat so the seal is even all the way around.

Seat the toilet flapper evenly with no twist in the chain

1. Shut off the supply, flush to lower the tank, and look at how the flapper sits on the flush valve seat.
2. Straighten the chain so links hang without a corkscrew twist between the handle arm and the flapper eye.
3. Set chain slack so the flapper can seal fully (about a little free play — not taut), then refill and watch for a continuous trickle.
4. If one side still lifts, reseat the flapper ears on the overflow posts evenly — do not add another twist to “shorten” the chain.

If the chain is untwisted but you are not sure how much slack to leave, see how much slack a toilet flapper chain should have.

Honest stop: a warped seat or cracked flush-valve seal needs a new valve kit — a perfect chain will not seal a damaged ring.

More help

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• Related fixes elsewhere: Toilet keeps running — flapper check first · Toilet flapper — set chain slack to about one finger width