How to Fix a Running Toilet

Water, the silent thief of your monthly utility bill, often makes its escape through the tank of a running toilet. When you hear that persistent trickling sound long after a flush, it signals that the seal inside your tank has failed or the fill level is set too high for the overflow tube to manage. Fixing this is a rite of passage for any homeowner. You do not need a plumber to stop the cycle; you only need to understand the simple mechanical relationship between the water float and the flapper valve at the bottom of the tank. Master this repair, and you will save hundreds of gallons of water and eliminate the phantom flushing sounds for good.

1. Find the leak culprit. Remove the tank lid and listen for the hissing of water. If water is spilling into the overflow pipe, your float is set too high; if it is quiet but the tank periodically refills, your flapper is leaking.
2. Lower the float precisely. Locate the adjustment screw on the fill valve assembly. Turn it counter-clockwise to lower the float ball or cup so the water level sits about an inch below the top of the overflow pipe.
3. Scrub away mineral deposits. Shut off the water valve behind the toilet and flush to empty the tank. Use a sponge or abrasive pad to scrub the rubber flapper and the plastic seat where it rests to remove mineral buildup.
4. Perfect the chain slack. Examine the chain connecting the flush handle to the flapper. If it is too tight, the flapper won't seal; if it is too loose, it will get caught under the seal.
5. Install the new flapper. If the rubber is cracked or warped, unhook the old flapper from the pins and slide on a new one of the same size. Most modern toilets use a standard two-inch or three-inch flapper.
6. Verify the silent seal. Turn the water supply back on and wait for the tank to fill. Once full, listen carefully for at least five minutes to ensure the fill valve shuts off completely and stays silent.