How to Fix a Running Toilet Without a Plumber

A running toilet is usually caused by a warped flapper, incorrect chain length, or water level issues that you can fix in 15 minutes with basic adjustments.

1. Open Up the Tank. Carefully lift the ceramic or plastic lid straight up and set it on a towel on the floor. The lid is heavy and can crack easily, so handle it gently. Look inside the tank to see the flapper, chain, and float mechanism.
2. Find the Leak Source. The rubber flapper at the bottom should sit flat against the flush valve seat. If it's warped, cracked, or has mineral buildup preventing a good seal, gently clean around the edges or replace it. Press it down firmly to see if the running stops.
3. Fine-Tune the Chain. The chain connecting the flush handle to the flapper should have about half an inch of slack. If it's too tight, the flapper won't close completely. If it's too loose, the flapper won't lift when you flush. Move the chain to a different hole on the flush arm to adjust the length.
4. Lower the Waterline. Water should sit about an inch below the rim of the overflow tube. If it's too high, it will continuously flow into the overflow tube. Bend the float arm down to lower the water level, or adjust the screw on newer fill valves to reduce the water level.
5. Verify the Fix Works. Put the lid back on and flush the toilet several times to make sure everything works properly. The running should stop within 10-15 seconds after flushing. If it continues to run, double-check that the flapper is sealing and the chain length is correct.