A flapper is the least expensive part of a toilet, but the thing that can cost you the most. The flapper is the plastic flap that covers the bottom of the toilet tank (not the bowl). When you flush the toilet, the arm of the handle has a chain attached that pulls up and opens the seal between the flapper and the toilet tank gasket. This empties the water from the tank into the bowl, and causes the water in the bowl to “flush” down the sewer pipe. Once the water leaves the tank, gravity takes hold of the flapper and it drops down to create the seal again, so the tank can fill up with water again, and wait for the next flush.
The chemicals in the water break down the plastic of the flapper and the tank gasket, and as they age, the seal between them leaks. It is a silent running, if you will, because you cannot hear this leak, and it will continue to get worse and leak more volume of water as time goes on as the seal weakens. What you might hear is the water fill stem turning on and off as it tries to keep the water of the tank where it should be, compensating for the leaking flapper ball.
You can detect this leak simply by observing the toilet bowl with the lid up, of course. You will notice a steady, small, stream of water flowing down the sides of the bowl into the water. You can also confirm this by watching your water meter, when you know there is no water running in the house or condominium. Usually the meter will spin a bit, then stop, then spin again. This is a typical flapper leak cycle.
Prices for flapper balls range from 3.50 to 7.50 depending on the type you need. It is easy to replace one, anyone can do it. They should be replaced once a year.
Not replacing the flapper can cost you hundreds of dollars per year, per toilet. Water suppliers, cities, town, counties, charge based on usage, and some also charge your sewer based, not on the number of toilets, but on the water usage. So your over use of water can cost you double.
If you live in a condominium association or an HOA, with a common meter, the costs can escalate. It is more difficult to inspect vacant units, when the association does not have keys or rights of access. It is more difficult to watch the meter, in the middle of the night, and to know when absolutely no one is using the water when the meters supplies water to 50 or 100 condominiums.
It may be more practical for a condominium association to adopt a rule requiring every owner to have their toilets inspected and the flappers replaced once a year. Perhaps the association can cut a deal, at a reduced price, if all of the toilets can be serviced on a particular day, and billed separately to each unit owner by the plumber. The toilets are not the responsibility of the community association, but paying the water bill is. That gap is where the leaking toilets fall through. Vacant units are common problems, because they are not inspected very often. A leaking flapper can start, and over a period of many months without being inspected can result in a Niagra Falls of a water leak 24/7. Whatever your solution, have a plan, so that you are not caught watching your dollars go down the drain due to a leaking flapper in a toilet.