How to Replace a Toilet Flapper

Before you start

Confirm the flapper is actually the problem. Tint the tank water with food dye and leave the toilet unflushed for twenty minutes. If colour appears in the bowl, water is leaking past the flapper.

• A replacement flapper sized to your flush valve, commonly two-inch or three-inch
• A towel or sponge
• Rubber gloves, if you prefer
• The old flapper in hand when buying, or the toilet's model number from inside the tank

Step by step

1. Shut off the supply. Turn the small valve behind the toilet clockwise until it stops.
2. Flush to empty. Hold the handle down so the tank drains as fully as possible.
3. Sponge the rest. Remove remaining water from the bottom of the tank.
4. Unhook the chain. Detach the lift chain from the flush lever arm.
5. Remove the old flapper. Slide its ears off the pegs on the overflow tube, or remove the ring if it slips over the tube.
6. Fit the new one. Attach it the same way, centred over the flush valve opening.
7. Set the chain. Leave about a centimetre of slack. Too tight keeps the flapper open; too loose prevents a full flush.
8. Restore water and test. Turn the supply back on, let the tank fill and repeat the dye test.

Mistakes to avoid

• Ignoring the valve seat. Scale on the flush valve seat can keep even a brand-new flapper from closing tight. Wipe the seat clean with a scouring pad.
• Using a universal flapper on a specialty toilet. Some models need a manufacturer-specific part.
• Overtightening the shut-off. Older valves may start leaking at the stem if forced.
• Leaving too much chain. Extra links can catch under the flapper and hold it open.

Choosing the right part

Hardware stores stock flappers in several styles: standard rubber, adjustable models that let you regulate flush volume, and specialty designs for particular brands. If your toilet is a low-flow model, match the original part closely, since an adjustable universal flapper may change the flush volume and leave the bowl incompletely cleared.

When the old flapper comes out, look at its condition. A slimy, swollen or stiff surface confirms it had failed. If the old part looks nearly new, the leak may lie elsewhere, perhaps at a cracked overflow tube or a fill valve that overfills.

When to call

If a new flapper still leaks, the flush valve itself may be cracked or the fill valve may be overfilling into the overflow tube. Other symptoms such as a rocking bowl or a base leak belong in our toilet repair service, and a cracked or very old fixture may be better replaced through toilet installation. For a broader look at noisy, constantly running toilets, read how to fix a running toilet. Small maintenance jobs elsewhere, such as cleaning a faucet aerator, are just as simple. Unrelated hot-water problems are handled through water heater repair.

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