Why is my toilet running constantly after flushing?

A constantly running toilet wastes water and annoys everyone. Learn how to diagnose and fix the flapper, fill valve, or flush tube issue quickly.

Category:Plumbing

Difficulty:Easy

Time:15 min

Success:50%

Updated:Jun 15, 2026

quick_referenceQuick Answer

For Why is my toilet running constantly after flushing?, start with "Check the flapper seal": Remove the tank lid and flush. Watch the flapper as it closes. If it doesn't seat evenly or lifts back up, the chain may be too tight or the flapper is warped. Stop DIY if water is leaking from the base of the toilet onto the floor. This is listed as a easy recovery and usually takes about 15 min.

verifiedGuide Snapshot

Repair areaPlumbing

Estimated time15 min

DifficultyEasy

Stop conditions3

Last updated Jun 15, 2026. Review the stop conditions before continuing.

account_treeRecovery State

DeviceToilet

Current stateWater Leak

Specific stateRunning Toilet

Failed stepFlapper Wear

Likely failure typeWorn Part

DIY boundaryDIY recovery first

paymentsCost decision

help1. Understand the Problem

A toilet that runs non-stop after flushing usually means water is leaking past the flapper into the bowl or the fill valve isn't shutting off properly. This is almost always caused by a worn flapper, a misadjusted float, or a stuck fill valve. Identifying which part is failing will let you fix it in minutes with basic tools.

build_circle2. Try This First

Best First Step

Check the flapper seal

Remove the tank lid and flush. Watch the flapper as it closes. If it doesn't seat evenly or lifts back up, the chain may be too tight or the flapper is warped.

visibility3. Visual Guidance

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

Adjust the float heightLocate the float (cup or ball). Turn the adjustment screw or pinch the clip to lower the float so water stops 1/2 inch below the overflow tube.

Clean the fill valve seatIf the valve still leaks, shut off water, remove the fill valve cap, and wipe the rubber diaphragm with a cloth to remove grit.

Replace the flapperIf the flapper is cracked or mushy, unhook it from the ears and replace with a universal model. Ensure the chain has 1/4 inch of slack.

autorenew4. If That Doesn't Work

Try the next recovery options.

Replace the entire fill valveIf adjusting the float doesn't stop the running, the fill valve may be worn internally. Install a universal replacement kit.

chevron_right