How to Fix a Running Toilet

Three Common Causes

Flapper: The rubber seal at the bottom of the tank. If worn or warped, water leaks into the bowl. Replace for $5-$10.
Float: If the water level is too high, water runs over the overflow tube. Adjust the float down.
Fill valve: If it hisses continuously, the fill valve needs replacement ($10-$15 for a Fluidmaster kit).

Quick Diagnosis

Remove the tank lid. If water is flowing into the overflow tube, adjust the float. If water leaks past the flapper (food coloring test), replace the flapper.

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