7 Reasons why the flapper/flush-valve won’t close:

1)  The flapper is “stuck” to the overflow pipe.
One observable symptom: it is not bobbing or floating in the water, regardless of the water height, and appears to be partially or fully upright.

2)  The chain is tangled.
A chain link can get stuck on the metal clip or loop over the top of the lever arm. Although an improper chain length causes many of these problems, “slapping” the flush handle can also cause the chain to hang up.

3)  A clogged drain/obstructed pipe produces back pressure through the flush valve seat.
The obstruction doesn’t allow the water level inside the tank to drop low enough for the flapper to seat properly. In this instance, the flapper appears to “hover” in the water above the flush valve seat. A clogged or obstructed drain pipe is the most common reason for toilets to overflow the bowl.

4)  A “universal” replacement flapper is purchased.
When a “universal” replacement flapper is purchased, it does not seat properly on the flush valve. Flappers should be purchased according to the type of flush valve used because universal flappers can leak and/or fail to seat up to 50% of the time.

5)  The flush handle/lever is old, defective, or “sticking” to the inside of the toilet tank.
Old or defective equipment can result in the flapper being held open.

6)  The flapper hinges are weakened and/or degraded.
This allows the flapper to slide to the side and not seat properly on the flush valve. (Note: the water flow from the fill valve can also push the flapper to one side if it is above 60 PSI.)

7)  A flapper’s buoyancy doesn’t become “negative” until the tank completely evacuates.
This does not allow the flapper to seat properly. Although there are several known causes (including toilet design), the most common is a clogged or obstructed drain pipe, which creates back pressure into the tank through the flush valve.


5 Common reasons why wide-open flappers often go undetected:

1)  No one is home to hear it running.
Often times, a person will use the bathroom before they leave their home (or business). In this case, a wide-open flapper would not be detected until the person returned home and realized the problem. This could be hours, or even the following day.

2)  The bathroom is not used frequently.
A wide-open flapper in secondary bathrooms (a finished basement or guest bathroom) can go undetected for days or weeks, wasting a tremendous amount of water and resulting in a high water bill.

3)  Hearing impaired/challenged people may fail to recognize a problem exists.
People with moderate to severe hearing loss may be unable to hear the running water. People afflicted with tinnitus may be unable to distinguish the sound of the running water from their tinnitus.

4)  The sound of the toilet tank refilling is a muted hum.
The initial flush of a toilet is loud, brief, and occurs while the user is still in the bathroom. However, the refilling of the toilet is quieter, prolonged, and typically finishes after the user has left the bathroom. Therefore, the user is unaware when the flapper remains wide-open.

5)  Background noise can easily mask the sound of a wide-open flapper or flush valve.
Examples include central air conditioners and HVAC systems (while the fan is operating); ceiling and window fans; music and/or TV; etc.