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STANDARD GRAVITY TANK · EAR-MOUNTED FLAPPER

Replace the flapper.
Then prove the seal.

Check the cause, match the part, and see the repair in 3D. This guide covers a rubber flapper that attaches to two mounting ears inside a conventional gravity toilet tank.

Check the fit first. Canister, tower, dual-flush, pressure-assisted and concealed-tank systems need their own instructions. The model-specific instructions for your toilet and replacement part take priority.

01 / DIAGNOSE BEFORE YOU BUY

A running toilet has more than one cause.

Lift the lid carefully and place it somewhere secure. Look at what happens after the tank fills.

  • Water runs over the overflow opening: check the water-level or fill-valve problem first.
  • The chain or handle catches: a tight or tangled chain can hold a good flapper open.
  • The refill hose sits below the tank waterline: incorrect hose position can cause siphoning. Follow the manufacturer’s placement instructions.
  • The flapper or sealing surface is worn: water may leak from the tank into the bowl.

A dye-positive bowl confirms a tank-to-bowl leak, but it does not prove that the flapper is the only faulty part. Rule out the other causes before replacing it.

Diagnostic references: Kohler running-toilet checksRefill-hose position

02 / COMPATIBILITY & PREPARATION

The right size is only the start.

Find the toilet’s make and model. Common flapper flush-valve openings are approximately 2 or 3 inches. Measure the opening, not the old flapper’s outside width. Confirm the mounting style and any flush adjustment settings too.

Check Korky’s sizing guide ↗

Your parts and tools checklist

  • A compatible replacement flapper and its instructions
  • A towel and a soft cloth or sponge
  • A ruler or tape measure
  • Food coloring or a toilet leak-detection dye tablet

Most ear-mounted flappers unhook and reconnect by hand. Check your replacement part’s instructions for any extra tools. Do not force a stuck shutoff or damaged fitting.

Before you begin

These checks are for your use. They do not certify compatibility and are not saved.

03 / STRAIGHT TO THE REPAIR

See how the parts move.

3D REPAIR GUIDE62 seconds · Niki narration
Ear-mounted flapper, conventional gravity tank. AI-created cutaway visualization with visible captions and time compression. Read the compatibility, safety and testing steps; the video is not model-specific.

The video shows shutoff and draining, unhooking the old flapper, cleaning the sealing rim, installing the replacement, reconnecting the chain, refilling and testing. It compresses elapsed time; a 62-second video is not a promised repair duration.

04 / REPLACE THE FLAPPER

Work gently. Check as you go.

  1. Close the supply and drain. Gently operate the toilet shutoff by hand as its design requires. Flush and hold the handle down. Confirm the tank does not refill. Stop if the valve sticks, leaks or fails to stop the flow.
  2. Remove the old flapper. Note the chain connection, unhook the chain, and release both flapper ears from their mounting points.
  3. Clean the seat gently. Use a soft damp cloth to remove loose debris from the sealing rim. Stop for a damaged seat or cracked parts; do not scrape or force a seal.
  4. Fit the compatible replacement. Attach both ears. Check that the flapper lifts and falls freely and sits squarely over the opening.
  5. Reconnect and adjust the chain. Use the slack specified by the replacement manufacturer. It must lift the flapper without holding it open at rest or falling underneath it. Follow the instructions for any adjustment dial.
  6. Reopen the water gently. Watch the refill and check for new drips. Continue with the success checks below.

Procedure references: Korky replacement instructionsFluidmaster model instructions

05 / PROVE THE REPAIR

Quiet is not the only check.

  1. Let the tank fill. Confirm filling stops at the toilet’s intended waterline, below the overflow opening.
  2. Flush several times. The flapper should lift, settle and seal each time, without a snagging chain.
  3. Add a few drops of food coloring to the tank. Wait 10 minutes without flushing.
  4. If color appears in the bowl, a leak remains. Flush immediately after the test to reduce staining risk.
  5. Check the shutoff, supply connection and floor for new drips. Listen for unprompted refilling afterward.

If the leak remains, recheck fit and chain adjustment. A damaged flush-valve seat or another problem may need a different repair.

EPA WaterSense dye-test guidance

KNOW YOUR LIMITS

Stop and get qualified help when…

  • The shutoff is stuck, leaking, or does not stop the water.
  • You find cracked ceramic, damaged mounting parts or a damaged sealing seat.
  • Water is leaking outside the toilet.
  • The correct part and adjustment do not resolve the leak, or you are unsure of the diagnosis.

Do not handle sharp broken ceramic. A new flapper cannot solve every fill-valve, flush-valve, gasket or tank problem.

For a professional quote, ask what is included: diagnosis, parts, labor, callout charges, tax and any warranty. Compare that with the parts and tools you would need to buy.

Compare your costs →

Water Corporation leak and shutoff guidance

CHECKED OCTOBER 11, 2026

Sources & scope.

Written instructions are based on the manufacturer and public-water resources below. The 3D visualization depicts a common mechanism; it has not been independently certified for every toilet model.

These are information links, not affiliate links. We do not sell tools or parts.