If the flapper is worn or the seat that the flapper rests on is damaged, the water level will stop just below the flapper. If the gasket that seals the flush valve into the tank is deteriorated and leaking, the water would most likely drain completely out of the tank.
While toilet flappers are normally pretty durable, they can wear out over time. The average toilet flapper lasts about 4 to 5 years. It is important that you replace your toilet flapper when needed to prevent damaging leaks.
One easy, but temporary fix to make rubber toilet parts supple again is vaseline. The toilet must be drained and dried for this to work. Then, vaseline can be rubbed on the flapper and it's connecting washer until they become soft. The toilet should be filled and checked again.
It is a good idea to turn the water off to the toilet before replacing the flapper, though you can replace some styles in under a minute! Just one less distraction from doing the best job you can.
However, over time a flapper will eventually corrode, crack, and start to leak. A leaking flapper allows water to leak into the bowl of your toilet, which is wasteful, and can waste hundreds of gallons of water per year if not fixed.
However, the tradeoff is they corrode over time and will generally need to be replaced about every two years or so. There's more good news: you can replace a toilet flapper yourself! They cost just a few dollars at your local hardware store, and require no specialized tools or training to replace it.
If the toilet keeps running or runs intermittently, you're not getting a good seal. Try a different flapper if the toilet won't stop running. If you just can't find a flapper that seals, consider replacing the entire toilet overflow tube/flapper. On most toilets (two-piece), this means removing the tank.
Flappers tend to deteriorate over time, usually because of their constant interaction with in-tank cleaning products and chemicals found in the water. They can cause the flapper to warp, crumble, and eventually lose its seal over the flush tube, allowing water to leak through.
How much water does a bad flapper waste? Depending on the extent of the leak, a warped or poorly fitting flapper can waste up to 200 gallons of water a day and may cost you hundreds of dollars a year.
Replacing a Flapper Valve
Although durable, the flapper can wear out over time, providing a less-than-perfect seal. The result is an audible trickle, punctuated by an occasional surge of supply water topping off the tank.
A typical flapper lasts between 3 and 5 years. When a flapper begins to fail, it loses its ability to create a water-tight seal with the flush valve, resulting in a leak. You can typically tell there is a leak in your toilet from the telltale sound of dripping water.
If your loo is constantly dribbling, it's probably leaky. What's a leaky loo? A 'leaky loo' usually refers to clean water leaking from your cistern down into your toilet bowl. If you have one, you may notice a steady trickle of water at the back of the bowl or hear a constant dripping sound inside the tank.
If a toilet randomly runs for a few seconds and empties without flushing, it's likely the result of a cracked toilet flapper, the chain being caught, the float needing to be lowered, or the refilling tube needing to be repositioned.
Check Your Intermittently Running Toilet for Leaks
If your water level drops below the pencil mark, you have a leak in your tank. A leak indicates a faulty flapper or flush valve. If you have no leak, the fill valve is the culprit. Leave the water off for a couple hours and see where the water level drops to.
According to Fixr, the average toilet valve repair cost is between $75 and $200 to replace a flush valve or up to $400 to fix a constantly running toilet. This includes the cost of the plumber's time for the toilet repair and the cost of the toilet parts.
Are all toilet flappers universal? No. There are universal designs like the Fluidmaster flappers that replace most other flappers and there are specialty flappers for specific flushing systems.
A silent toilet leak (the one you usually can't hear) can waste around 500 to 800 gallons of water per day! The ones you can hear will waste much, much more. Such waste can typically be attributed to a faulty water level adjustment or a leaky flapper.
The most common toilet leak is caused by a deteriorated flush valve (flapper) at the bottom of the toilet tank. If the flapper does not seat properly, water will leak into the toilet bowl. Often this leak will occur without being heard.
The most common are where bolts have become loose, the misalignment of pipes and valves, or the wax ring not sealing properly. You should be able to tell by sight where there is water leaking. In some instances, tightening the bolts or resealing a seal is enough to fix the problem.
The only-when-flushed toilet leak could be caused by loose mounting bolts or a worn-out wax gasket while the all-the-time leak could be caused by a loose water supply line connection, a problematic water shutoff valve, or a faulty seal between the toilet tank and its base.
Petroleum jelly is waterproof, but to get it to stick to your flapper, you need to drain the tank and let the flapper dry out. A liberal coating around the bottom of the flapper will revitalize the rubber and make it supple again. It should once again mold around the rim of the siphon hole and make a seal.