Repairing a Toilet Leak
These repair tips are designed for easy do-it-yourself use. However, if you feel unsure about your ability to perform any of these steps, contact a licensed plumber.
Check the float arm; lift it up. If the water stops running then you’ve found your problem. Adjust the screws or bolts to the inlet float valve until the water stops flowing.
If the water continues to run, turn off the water supply valve to the tank. Flush the toilet to drain out the water. Examine the inlet float valve by removing the two screws or bolts and lifting the top of the valve housing out. If it is even slightly damaged or worn, replace it.
If the toilet continues to run, examine the ball stopper or flapper valve. It should fit flush in its seat. If not, look at the lever and guide rods that operate the flapper valve. If they are crooked, gently straighten them. For toilets with a chain pull attached to the flapper valve, make sure the chain is slack when the valve is seated to ensure a snug fit. If the ball or flapper valve is worn out, replace it. Check for corrosion or deposits on the ball stopper or flapper valve. Use steel wool to remove build up so the stopper sets properly in the seat.
Inspect the small refill tube that connects the fill valve to the refill-overflow tube to be sure the smaller tube ends slightly above the standing water level of the completely filled tank. If necessary, gently pull the small tube upward until its end is correctly placed.