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When does a toilet flapper seal need replacing?
An occasional run-on after flushing can come from a flapper that isn’t seating cleanly, but I’m not sure how much can be fixed by cleaning the sealing surface. If gently lifting the handle stops the running, what does that observation actually tell you about the flapper, chain, or handle adjustment?
For the seal itself, what signs matter most: visible warping, stiffness, mineral buildup, or whether it still sits evenly on the valve seat? And how much does the toilet model affect replacement choice? I’d rather not assume a generic flapper will fit every flush valve.
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2 replies
If gently lifting the handle stops the water running, the linkage may be keeping the flapper slightly raised - often because the chain has too little slack or the handle is sticking. It can also help the flapper settle onto the seat, so it doesn’t prove the flapper is faulty. Check that the handle moves freely and the chain allows the flapper to close; persistent leaking despite free movement makes the seal or valve seat more suspect.
The most useful check is whether the flapper sits evenly against a clean valve seat. Mineral deposits can interfere with that contact, while warping or stiffness can keep the seal from conforming. Any one sign is suggestive rather than conclusive; a flapper that still looks sound but won’t seat evenly may still be leaking.
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