How to Fix a Running Toilet
Is your toilet running? If you hear the fill valve turn on, that doesn't always mean it has broken. In most cases, a worn toilet flapper or flush valve seal is allowing water to slowly leak from the tank into the bowl.
As the water level inside the tank drops, the fill valve float also drops and turns the water back on. Replacing the worn flapper or flush valve seal will usually fix this type of running toilet.
If water continues flowing after the tank is full, the fill valve float may be set too high, clogged with debris, or failing to shut off. Adjusting, cleaning, or replacing the fill valve will fix a constantly running toilet.
Test for a Leaking Flapper or Seal
Mark the Water Level
To test if your flapper is leaking, start by flushing the toilet. When it is done refilling, mark the water level of your tank with a pencil.
Turn off the Water Supply Line
Next, turn off the water supply valve and wait for at least 25 minutes. If the water level drops below the pencil mark, a part within your toilet tank is leaking.
Wait for a Few hours
Leave the water off for a couple of hours and see where the water level drops. If the water level drops to the flapper or flush seal, you need to replace it.
If the water level drops to a point on your overflow tube or the bottom of the tank, you need to replace your flush valve and tank-to-bowl gasket.
