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Why Is My Toilet Running Intermittently After Flushing?

A toilet that runs on and off usually has a worn flapper, a misadjusted fill valve, or a stuck float. Fix it in minutes without calling a plumber.

Category:Plumbing

Difficulty:Easy

Time:10 min

Success:50%

Updated:Jun 9, 2026

quick_referenceQuick Answer

For Why Is My Toilet Running Intermittently After Flushing?, start with "Check the Flapper Seal": Remove the tank lid and press down on the flapper with your finger. If the running stops, the flapper is worn and needs replacing. Stop DIY if water is leaking from the base of the toilet. This is listed as a easy recovery and usually takes about 10 min.

verifiedGuide Snapshot

Repair areaPlumbing

Estimated time10 min

DifficultyEasy

Stop conditions3

Last updated Jun 9, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceToilet

Current stateRunning Toilet

Specific stateFlapper Leak

Failed stepFlapper Wear

Likely failure typeWorn Part

DIY boundaryDIY recovery first

paymentsCost decision

help1. Understand the Problem

Intermittent running means water is slowly leaking from the tank into the bowl, causing the fill valve to kick on periodically. This is almost always due to a flapper that no longer seals properly or a float that's set too high.

build_circle2. Try This First

Best First Step

Check the Flapper Seal

Remove the tank lid and press down on the flapper with your finger. If the running stops, the flapper is worn and needs replacing.

visibility3. Visual Guidance

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

Turn Off the Water SupplyLocate the shut-off valve behind the toilet and turn it clockwise to stop the water flow.

Inspect the FlapperLift the flapper and check for cracks, warping, or mineral buildup. A soft, pliable flapper is good; a stiff one is bad.

Replace the FlapperRemove the old flapper by unhooking it from the ears, then attach a new universal flapper of the same size.

Adjust the Float HeightTwist the adjustment screw on top of the fill valve to lower the water level 1/2 inch below the overflow tube.

autorenew4. If That Doesn't Work

Try the next recovery options.

Replace the Fill ValveIf adjusting the float doesn't stop the running, install a new Fluidmaster fill valve to fix persistent water flow.

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Frequently Asked Questions

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warning5. Stop DIY If

Don't continue if any of these apply.

reportWater is leaking from the base of the toilet

reportThe fill valve is cracked or spraying water

reportYou see rust or corrosion on the tank interior

Still stuck?Get personalized help with AI Recovery.

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Similar Failure Pattern

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This page provides general DIY guidance.
If you're unsure, it's always best to consult a professional.