Fix Running Toilet

Learn how to fix a running toilet by inspecting and repairing common issues with the flapper, fill valve, and float.

Medium · 20–40 minutes

Tools

  • Adjustable wrench
  • Screwdriver
  • Towel or sponge

Materials

  • Replacement flapper (if needed)
  • Replacement fill valve (if needed)

Safety

  • Turn off the water supply to the toilet before starting repairs.
  • Wear gloves to protect your hands from dirty water and cleaning chemicals.
  • Dry up any spilled water promptly to prevent slips.
  • Do not overtighten plastic parts to avoid cracking.
  • If you notice leaks after repair, stop and consult a professional.

Steps

  1. Step 1: Turn off the water supply

    • Locate the shut-off valve behind the toilet and turn it clockwise to stop water flow.

    Check: Ensure water is completely off by flushing the toilet and confirming the tank does not refill.

  2. Step 2: Remove the tank lid

    • Carefully lift the toilet tank lid and set it aside on a flat surface.

    Check: Check that the lid is placed securely to prevent breakage.

  3. Step 3: Inspect the flapper

    • Look at the rubber flapper at the bottom of the tank. If it is warped, cracked, or doesn’t seal properly, it may need replacement.

    Check: Confirm the flapper is sealing tightly against the flush valve.

  4. Step 4: Replace the flapper if necessary

    • Disconnect the chain and unhook the old flapper from the pegs.
    • Attach the new flapper and reconnect the chain, ensuring proper length (slightly slack when at rest).

    Check: Test the flapper movement by pressing the flush lever and ensuring it drops back into place.

  5. Step 5: Check the float and fill valve

    • Examine the float to ensure it moves freely and is not set too high.
    • Adjust the float arm or screw to set the water level about 1 inch below the top of the overflow tube.
    • If the fill valve is faulty or leaking, replace it according to manufacturer instructions.

    Check: Verify the float does not stick and the fill valve shuts off water at the correct level.

  6. Step 6: Turn the water supply back on and test

    • Slowly turn the shut-off valve counterclockwise to restore water.
    • Allow the tank to fill and flush the toilet several times to check for proper operation.

    Check: Ensure the toilet stops running after each flush and there are no leaks around the base or inside the tank.

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plumbing

Fix Running Toilet

Medium20–40 minutes

Learn how to fix a running toilet by inspecting and repairing common issues with the flapper, fill valve, and float.

Was this guide helpful?
Safety Warning
  • Turn off the water supply to the toilet before starting repairs.
  • Wear gloves to protect your hands from dirty water and cleaning chemicals.
  • Dry up any spilled water promptly to prevent slips.
  • Do not overtighten plastic parts to avoid cracking.
  • If you notice leaks after repair, stop and consult a professional.

Tools & Materials

  • Adjustable wrench
  • Screwdriver
  • Towel or sponge
  • Replacement flapper (if needed)
  • Replacement fill valve (if needed)

Step-by-Step Instructions

Step 1

Turn off the water supply

Diagram for step 1: Turn off the water supply
  • Locate the shut-off valve behind the toilet and turn it clockwise to stop water flow.
Check

Ensure water is completely off by flushing the toilet and confirming the tank does not refill.

Was this step clear?
Step 2

Remove the tank lid

Diagram for step 2: Remove the tank lid
  • Carefully lift the toilet tank lid and set it aside on a flat surface.
Check

Check that the lid is placed securely to prevent breakage.

Was this step clear?
Step 3

Inspect the flapper

Diagram for step 3: Inspect the flapper
  • Look at the rubber flapper at the bottom of the tank. If it is warped, cracked, or doesn’t seal properly, it may need replacement.
Check

Confirm the flapper is sealing tightly against the flush valve.

Was this step clear?
Step 4

Replace the flapper if necessary

Diagram for step 4: Replace the flapper if necessary
  • Disconnect the chain and unhook the old flapper from the pegs.
  • Attach the new flapper and reconnect the chain, ensuring proper length (slightly slack when at rest).
Check

Test the flapper movement by pressing the flush lever and ensuring it drops back into place.

Was this step clear?
Step 5

Check the float and fill valve

Diagram for step 5: Check the float and fill valve
  • Examine the float to ensure it moves freely and is not set too high.
  • Adjust the float arm or screw to set the water level about 1 inch below the top of the overflow tube.
  • If the fill valve is faulty or leaking, replace it according to manufacturer instructions.
Check

Verify the float does not stick and the fill valve shuts off water at the correct level.

Was this step clear?
Step 6

Turn the water supply back on and test

Diagram for step 6: Turn the water supply back on and test
  • Slowly turn the shut-off valve counterclockwise to restore water.
  • Allow the tank to fill and flush the toilet several times to check for proper operation.
Check

Ensure the toilet stops running after each flush and there are no leaks around the base or inside the tank.

Was this step clear?

Common Mistakes

  • ×Not turning off the water supply before starting repairs.
  • ×Incorrectly installing or adjusting the flapper or float.
  • ×Overtightening plastic parts, causing cracks or leaks.
  • ×Using the wrong replacement parts for your toilet model.
  • ×Forgetting to check for leaks after finishing the repair.

When to Call a Professional

  • If you notice persistent leaks after attempting repairs.
  • If the shut-off valve is stuck or leaking.
  • If the toilet tank or bowl is cracked.
  • If you are unsure about any step or feel uncomfortable working with plumbing components.

Notes

  • Keep the area around the toilet dry to prevent slips.
  • Take a photo of your toilet’s internal parts before disassembly to help with reassembly.
  • Replacement parts are available at most hardware stores—bring the old part for comparison if possible.
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