Replace a worn toilet flapper
Fit the right flapper, adjust the chain and stop water quietly leaking from tank to bowl.
Home · 30–45 min · Easy
Before you start
Set the heavy porcelain lid flat on a towel away from the work area. Close the supply gently; stop if the valve is seized or begins leaking. Do not loosen the tank bolts or remove the flush valve for this repair. Wash hands after working inside the tank.
Tools and materials
- Compatible replacement flapper and chain
- Towel, small sponge, gloves and soft cleaning cloth
- Toilet leak-detection dye or a few drops of food coloring
Check the problem
Confirm a tank-to-bowl leak
Once filling stops, add a few drops of food coloring to the tank and wait 10 minutes without flushing. Color appearing in the bowl confirms a leak, but not necessarily a bad flapper. Flush immediately after the test to avoid staining.
Check the seat, chain and part type
Watch the closed flapper: the chain must not hold it up, and water must not spill over the overflow tube. A hardened or distorted flapper is a replacement candidate. Match the toilet model and valve to a compatible part; a damaged seat or overflow problem needs a different repair.
Steps
Shut off and drain the tank
Lift the lid onto a towel. Gently close the supply valve, flush and hold the handle down to empty most tank water. Sponge the small amount around the flapper if needed.
Detach the old flapper
Photograph any chain float or adjustment first. Unhook the chain from the lever, then release the flapper ears from their mounting posts. Do not bend or break the overflow tube. Ring-mounted designs must be removed as their instructions specify.
Clean and inspect the sealing rim
Wipe the flush-valve seat with a soft cloth. Remove grit without scratching it, and inspect for cracks or uneven damage. A new flapper will not reliably seal a damaged seat; stop if the seat needs repair.
Fit the matching replacement
Attach the new flapper using its correct mounting points. Check that it swings freely and settles squarely over the seat. If it has a float or adjustable closing setting, use the setting specified for your toilet—not a generic dial number.
Set the chain without pulling the seal open
Clip the chain to the lever hole that lifts the flapper straight up. Leave slight slack with the flapper fully seated. Secure excess chain so it cannot fall under the seal or catch other parts. Operate the handle and confirm the flapper returns freely.
Refill, flush and repeat the leak test
Open the supply and let filling stop at the toilet’s specified level. Flush several times: the handle should return, the flapper should reseat and filling should stop. Repeat the 10-minute dye test, then flush out the dye. If leakage remains, recheck fit, seat and chain rather than shortening the chain tighter.
Several complete flushes finish without handle assistance, refill stops normally, and no dye enters the bowl during the timed test.
Tips
Similar-looking is not enough
Match the toilet model and flush-valve opening, mounting style and required float or timing adjustment.
Too tight can cause the leak
The resting chain needs a little slack. Excess loose chain must stay out from under the seal.
Overflow is a different fault
If water runs over the overflow tube, investigate the fill valve and water level; replacing the flapper alone will not fix it.