Why Is My Toilet Running Constantly After Flushing?

A toilet that keeps running usually means a worn flapper or a misadjusted fill valve. Fix it in minutes without calling a plumber.

Category:Plumbing

Difficulty:Easy

Time:20 min

Success:50%

Updated:Jun 11, 2026

quick_referenceQuick Answer

For Why Is My Toilet Running Constantly After Flushing?, start with "Check the flapper for wear": Remove the tank lid and flush the toilet. Watch the rubber flapper at the bottom of the tank. If it does not drop back into place perfectly centered, or if it looks cracked or spongy, it needs replacing. Stop DIY if tank-to-bowl gasket is leaking water onto the floor. This is listed as a easy recovery and usually takes about 20 min.

verifiedGuide Snapshot

Repair areaPlumbing

Estimated time20 min

DifficultyEasy

Stop conditions3

Last updated Jun 11, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceToilet

Current stateRunning Water

Specific stateFlapper

Failed stepFlapper Wear

Likely failure typeWorn Part

DIY boundaryDIY recovery first

paymentsCost decision

help1. Understand the Problem

When your toilet runs long after flushing, water is leaking from the tank into the bowl. The most common causes are a deteriorated flapper that no longer seals, a fill valve set too high, or a chain that is too tight. This wastes up to 200 gallons of water per day.

build_circle2. Try This First

Best First Step

Check the flapper for wear

Remove the tank lid and flush the toilet. Watch the rubber flapper at the bottom of the tank. If it does not drop back into place perfectly centered, or if it looks cracked or spongy, it needs replacing.

visibility3. Visual Guidance

See what's happening and how to try the first recovery step.

Adjust the chain lengthCheck the chain connecting the flush handle to the flapper. It should have about 1/4 inch of slack. If it is too tight, the flapper will not seal. Remove excess links with pliers.

Clean the flapper seatTurn off the water supply and flush to empty the tank. Use a sponge and white vinegar to wipe the rim where the flapper seats. Mineral deposits can prevent a watertight seal.

Install a new flapperRemove the old flapper by unhooking it from the overflow tube. Attach the new flapper ears to the overflow tube pegs and clip the chain to the flush lever. Turn the water back on and test.

Adjust the water levelLocate the fill valve adjustment screw or float. Turn the screw clockwise to lower the water level, or pinch the float clip to slide it down. The water line should be 1/2 inch below the top of the overflow tube.