toilet flapper leaking after replacement

Why Toilet Flapper Is Leaking After Replacement?

Your toilet has been running water continuously unless the water is tuned off. You decided to replace the toilet flapper with a brand new one and yet the problem persists possibly worse.

Now why is your toilet flapper leaking after replacement? It is possible that the toilet flapper did not fit well on the flush valve seat due to roughness or a bend. This means you need to get a flush valve repair kit  so that the new flapper fits perfectly.

Below we will discuss other possible reasons your new flapper  still leaks after replacement and how to solve the issue using the flush valve kit correctly.

Why Toilet Flapper Leaks After Replacement?

So, you have diagnosed that your toilet flapper is malfunctioning or degraded and needs replacement. You went ahead and changed the flapper, but it failed, causing your new toilet flapper to leak.

Below are reasons why your new toilet flapper leaks.

The Toilet Flapper Didn’t Seat Properly

If the new toiler flapper doesn’t sit well, it won’t seal tightly on the valve seat, making the water leak into the toilet bowl from the tank. Moreover, the flipper won’t seal well if minerals accumulate on the flapper’s bottom.

Loose Chain

If the chain-link holding the handle arm and flapper is too long, it may get caught underneath the toiler flapper after flushing. This will cause intermittent but notable tank leaking.

Fortunately, you can effortlessly bridge the issue with your hand then afterward flush to ensure the toilet works. 

Excessively Tight Chain

Flushing the toilet can be impossible with a stuck or short flapper chain. You can effortlessly notice this problem if there’s tension when you push the toilet handle.

To solve this problem, adjust the combo slack of the flapper chain at approximately half an inch to ensure it does its intended job. 

High Water Pressure

While this is an unlikely scenario, it is plausible. A toilet flapper will only drain the correct amount of water down the toilet bowl if there is adequate water pressure. 

High water pressure will make your new toilet flapper leak. You can determine if the pressure is too high by reading the pressure gauge of your plumbing appliance.

Generally, water pressure in homes is typically about 30-60 PSI. Keep in mind that your kitchen appliances and the internal parts of toilets cannot handle more than 80 PSI.

See also Why is water disappearing from toilet bowl

How To Fix Toilet Flapper Leaking After Replacement?

A malfunctioning toilet flapper isn’t the only culprit for a leaky toilet. Therefore, once you replace the old flapper but the toilet continues to leak, you will need to figure out the problem and fix it.

Cracked Supply Line

The water supply line is a fundamental part of a toilet that most people overlook. Without it, your toilet won’t flush or replenish, so you must make sure it works properly. 

Regular maintenance and inspection will help you monitor the supply lines, allowing you to catch any problems early. The constant closing and opening of the fill valve produces vibrations that can weaken the supply lines.

Moreover, hard water can make the lines brittle forming cracks and eventually breakage. You can easily notice a cracked supply line because it causes puddling at the toilet base and even major flooding or total toilet failure. 

It’s recommended that you replace the water supply lines after 3 to 5 years to avoid failure or leakage. Furthermore, you should always install a new line when replacing your toilet. 

Fix a cracked supply line by:

  • Close the toilet valve
  • Empty the tank by holding down the tank lever
  • Remove the water supply line from the fill valve
  • Use an adjustable wrench to remove the water supply line from the shut off valve
  • Use an adjustable wrench to tighten the new water supply line
  • Fill the valve by tightening the new water supply line
  • Slowly turn on the valve to fill the toilet tank with water
  • Inspect for any leaks

Compromised Fill Valve Connection

The fill valve refills the toilet tank water level to the appropriate level after flushing. It’s designed with a float that triggers the fill valve to open, letting water go into the tank.

A nut connects the fill valve to the tank and is sealed inside the toilet tank with a gasket. Over time, the gasket can form cracks and get deformed, resulting in water leaks under the tank.  

Moreover, the connection point joining the tank to the fill valve can leak if it’s not tightened well or the gasket isn’t installed with the proper orientation. While this problem is rare, it could be the cause if you see water accumulating on the floor below the toilet.

Scrutinize the gasket looking for possible deformation and cracking before replacing it. In addition, tighten the nut securing the fill valve to the toilet tank using your hand.

Damaged Toilet Tank To Bowl Gas Gasket

This gasket is soft rubber made, and it offers a watertight seal between the bowl and tank. A broken gasket causes leaking at the toilet tank base. Fixing this problem requires a professional plumber. 

See also How to Protect Bathroom Floor from Urine

Damaged Toilet Wax Ring Or Closet Flange

A toilet flange or closet flange functions as the connection point between your sewage drainage system and the toilet and keeps the toilet secured to the floor. 

On the other hand, the toilet wax ring installed on the toilet flange forms a watertight seal between the sewer pipe and the toilet bottom. It prevents sewer gases or odour and leaks from escaping.

The parts work together, so the other won’t function properly if one fails. For instance, if the toilet flange cracks, making the toilet unstable, it will result in rocking movements, potentially breaking the wax ring. 

The outcome of the above occurrence is water leaking from the toilet base and frequently through the underneath ceiling. 

Unsuitable installation practices commonly cause this failure. For example, most people usually rock the toilet forward and backward during installation, leading to uneven compression of the wax material. 

Uneven wax compression potentially causes multiple leak points. Experts recommend making slight side-to-side twist motions as you place your new toilet on top of the wax seal.

Read also How to raise toilet flange 2 inches


What Are The Symptoms Of A Leaking Toilet Flapper?

Below are the tell-tale signs of a leaky toilet flapper:

  • Unusually high water bill
  • The toilet water runs for a longer time than usual or intermittently
  • A hissing sound as the tank refills
  • A lower flushing power
  • Funny smells, mildew growth, and mold
  • A wet toilet tank
  • Jiggling the handle does not stop flushing
  • Flooding if you left your home unattended for a prolonged time
  • Rippling water moving into the toilet bowl between different flushes

While the signs above indicate a problem with the toilet flapper, it doesn’t show if the issue is water damage-threatening. Therefore, consult a professional plumber for the correct assessment and expert replacement of the leaking toilet flapper.


Once you realise that the toilet flapper stills leaks after replacement the possible cause could be the flush valve seat is rough or corroded. Which means the flapper did not seat properly hence the leak continues.

The solution if for you to get a new flush valve repair kit so that the new flapper seats perfectly on the flush valve seat. The process is simple and can be done in 5 minutes without the need of a professional plumber.

What you need to do is ensure you turn the water off before replacing the flapper, seal the connections appropriately, and adjust the chain as necessary. Remember fixing leakages prevents water wastage and saves you money.

See also Toilet Paper Holder Left or Right?

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