Fix a Leaking Toilet

Stop the water, identify where the toilet leaks, replace or tighten the faulty accessible part, and test the repair. A leak at the floor during flushing may require toilet removal and a new seal; a damaged flange or soft floor needs a plumber.

Medium · 30–60 minutes for an accessible tank, supply-line, or fill-valve repair; 1–3 hours if removing the toilet and replacing the floor seal

Tools

  • Adjustable wrench
  • Screwdriver
  • Sponge or small cup
  • Bucket or shallow container
  • Flashlight
  • Utility knife
  • Gloves
  • Eye protection

Materials

  • Replacement toilet supply line, washer, flapper, fill valve, or flush valve as needed
  • Replacement wax ring or approved toilet seal if removing the toilet
  • Towels or rags
  • Household disinfectant
  • Replacement toilet tank bolts and washers if the existing hardware is corroded or damaged

Safety

  • Shut off the toilet's supply valve and verify that water stops before disassembling anything.
  • Wear waterproof gloves and eye protection, especially if the leak may contain sewage.
  • Do not overtighten porcelain or plastic fittings; they can crack.
  • Clean and disinfect contaminated water, then dry the area promptly to prevent mold and floor damage.
  • If the floor is soft, the flange is broken, sewage is backing up, or water cannot be stopped, shut off the home's main water supply and contact a licensed plumber.
  • Toilets are heavy and awkward; use safe lifting technique and get assistance when removing one.

Steps

  1. Step 1: Shut off and empty the toilet

    • Turn the shutoff valve clockwise until it stops. If it will not close or is leaking, shut off the home's main water supply.
    • Flush the toilet and hold the handle down to empty the tank as much as possible.
    • Sponge remaining tank or bowl water into a bucket, and place towels around the toilet and supply connection.

    Check: Confirm that the tank does not refill after flushing. · Dry the tank, supply line, tank bolts, and base so the leak source can be identified.

  2. Step 2: Locate the leak

    • Add a few drops of food colouring to the tank without flushing. If coloured water appears in the bowl, the flapper or flush valve is leaking.
    • Observe the toilet while it is dry. Water around the supply-line connection or shutoff valve indicates a supply connection or valve problem.
    • Check underneath the tank. Water around the tank bolts or the tank-to-bowl joint indicates a washer, bolt, or tank gasket problem.
    • If water appears at the floor only while flushing, suspect the wax ring or another floor-seal problem.

    Check: Run a dry tissue around each connection and watch for the first spot that becomes wet. · Do not assume water at the base started there; trace it upward when possible.

  3. Step 3: Repair an accessible tank or supply leak

    • For a loose supply connection, tighten the coupling slightly with an adjustable wrench while holding the fixed fitting steady. Replace the supply line or washer if tightening does not stop the leak.
    • For a leaking flapper, unhook the old flapper, install a compatible replacement, and ensure the chain has slight slack when the handle is released.
    • For a leaking fill valve, disconnect the supply line, remove the retaining nut inside or beneath the tank, install the compatible replacement valve, and adjust its height according to the manufacturer's instructions.
    • For leaking tank bolts or the tank gasket, remove and replace the hardware or gasket. Support the tank and tighten the bolts evenly by hand, alternating sides.

    Check: Make sure the fill valve is upright and the refill tube is clipped above the waterline inside the overflow tube. · Ensure the flapper closes flat and the flush handle moves freely. · Confirm that porcelain does not flex or crack while hardware is tightened.

  4. Step 4: Inspect a leak at the floor

    • Do not continue using the toilet if water leaks from the base during a flush.
    • Check whether the toilet rocks. Rocking can indicate loose mounting bolts, a failed seal, or flange damage.
    • If you are prepared to remove the toilet, disconnect the supply line, remove the mounting nuts, cut any caulk at the base, and lift the toilet straight up with assistance.
    • Remove the old wax ring or seal, plug the drain temporarily with a rag to block odors, and inspect the flange and surrounding floor.
    • Install a new wax ring or approved seal, set the toilet straight down without sliding it, and tighten the mounting nuts evenly until secure. Reconnect the supply line.

    Check: The toilet should sit firmly without rocking before the mounting nuts are fully tightened. · The flange should be intact and firmly attached, and the surrounding floor should be solid and dry. · Remove the drain-blocking rag before setting the toilet back down.

  5. Step 5: Refill and test the repair

    • Open the shutoff valve slowly and allow the tank to fill.
    • Check every repaired connection with a dry tissue.
    • Flush the toilet several times while watching the supply connection, tank hardware, bowl-to-tank joint, and floor around the base.
    • Clean and disinfect any leaked water, then dry the floor and nearby surfaces.

    Check: The tank stops filling at the marked water level or below the top of the overflow tube. · No connection becomes wet during or after flushing. · The toilet remains stable and no water appears at the floor seal.

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Fix a Leaking Toilet0 of 5 steps done

Written by AI, not checked by a tradesperson. How this works

Step-by-Step Instructions

Step 1 of 5

Shut off and empty the toilet

Diagram for step 1: Shut off and empty the toilet
Fig. 1Shut off and empty the toilet
  • Turn the shutoff valve clockwise until it stops. If it will not close or is leaking, shut off the home's main water supply.
  • Flush the toilet and hold the handle down to empty the tank as much as possible.
  • Sponge remaining tank or bowl water into a bucket, and place towels around the toilet and supply connection.
Check

Confirm that the tank does not refill after flushing. • Dry the tank, supply line, tank bolts, and base so the leak source can be identified.

Was this step clear?
Step 2 of 5

Locate the leak

Diagram for step 2: Locate the leak
Fig. 2Locate the leak
  • Add a few drops of food colouring to the tank without flushing. If coloured water appears in the bowl, the flapper or flush valve is leaking.
  • Observe the toilet while it is dry. Water around the supply-line connection or shutoff valve indicates a supply connection or valve problem.
  • Check underneath the tank. Water around the tank bolts or the tank-to-bowl joint indicates a washer, bolt, or tank gasket problem.
  • If water appears at the floor only while flushing, suspect the wax ring or another floor-seal problem.
Check

Run a dry tissue around each connection and watch for the first spot that becomes wet. • Do not assume water at the base started there; trace it upward when possible.

Was this step clear?
Step 3 of 5

Repair an accessible tank or supply leak

Diagram for step 3: Repair an accessible tank or supply leak
Fig. 3Repair an accessible tank or supply leak
  • For a loose supply connection, tighten the coupling slightly with an adjustable wrench while holding the fixed fitting steady. Replace the supply line or washer if tightening does not stop the leak.
  • For a leaking flapper, unhook the old flapper, install a compatible replacement, and ensure the chain has slight slack when the handle is released.
  • For a leaking fill valve, disconnect the supply line, remove the retaining nut inside or beneath the tank, install the compatible replacement valve, and adjust its height according to the manufacturer's instructions.
  • For leaking tank bolts or the tank gasket, remove and replace the hardware or gasket. Support the tank and tighten the bolts evenly by hand, alternating sides.
Check

Make sure the fill valve is upright and the refill tube is clipped above the waterline inside the overflow tube. • Ensure the flapper closes flat and the flush handle moves freely. • Confirm that porcelain does not flex or crack while hardware is tightened.

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Step 4 of 5

Inspect a leak at the floor

Diagram for step 4: Inspect a leak at the floor
Fig. 4Inspect a leak at the floor
  • Do not continue using the toilet if water leaks from the base during a flush.
  • Check whether the toilet rocks. Rocking can indicate loose mounting bolts, a failed seal, or flange damage.
  • If you are prepared to remove the toilet, disconnect the supply line, remove the mounting nuts, cut any caulk at the base, and lift the toilet straight up with assistance.
  • Remove the old wax ring or seal, plug the drain temporarily with a rag to block odors, and inspect the flange and surrounding floor.
  • Install a new wax ring or approved seal, set the toilet straight down without sliding it, and tighten the mounting nuts evenly until secure. Reconnect the supply line.
Check

The toilet should sit firmly without rocking before the mounting nuts are fully tightened. • The flange should be intact and firmly attached, and the surrounding floor should be solid and dry. • Remove the drain-blocking rag before setting the toilet back down.

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Step 5 of 5

Refill and test the repair

Diagram for step 5: Refill and test the repair
Fig. 5Refill and test the repair
  • Open the shutoff valve slowly and allow the tank to fill.
  • Check every repaired connection with a dry tissue.
  • Flush the toilet several times while watching the supply connection, tank hardware, bowl-to-tank joint, and floor around the base.
  • Clean and disinfect any leaked water, then dry the floor and nearby surfaces.
Check

The tank stops filling at the marked water level or below the top of the overflow tube. • No connection becomes wet during or after flushing. • The toilet remains stable and no water appears at the floor seal.

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Common Mistakes

  • ×Failing to shut off the water before removing a valve, supply line, or tank component.
  • ×Overtightening tank bolts, mounting nuts, or plastic supply connections and cracking porcelain or fittings.
  • ×Replacing a flapper when the actual leak is from the tank gasket, supply line, or floor seal.
  • ×Reusing an old wax ring after removing the toilet.
  • ×Ignoring a soft floor, persistent dampness, sewage odor, or a toilet that rocks.
  • ×Using the toilet before testing several flushes and checking underneath for hidden leakage.

When to Call a Professional

  • The shutoff valve will not stop the water or cannot be safely operated.
  • The flange is broken, badly corroded, loose, or below the finished floor.
  • The floor or subfloor is soft, swollen, stained, or visibly damaged.
  • The leak involves sewage, a persistent backup, or a damaged supply pipe inside the wall.
  • The toilet remains loose or leaks after a new seal is installed.
  • There is significant water damage, mold, or uncertainty about safely removing and resetting the toilet.

Notes

  • Tank, supply-line, flapper, and fill-valve leaks are usually repairable with replacement parts matched to the toilet model.
  • A leak at the floor during flushing commonly indicates a failed wax ring, but the flange and floor must also be inspected.
  • If the toilet is removed, have the replacement seal ready before starting and avoid leaving the drain open.

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