Toilet Leaks Only When Flushed. How To Fix It?

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Last Updated on September 6, 2022 by acechapman

Leaks are one of the most common plumbing problems homeowners have to address. One or more of these problems could be a result of the toilet that leaks when flushed.

  • The supply valve and fill valves are loose.
  • The bolts that connect the tank to the other parts of the toilet don’t fit together.
  • The toilet tank has cracked.
  • The flapper is not closing correctly over the valve seat, which causes the flush valve leakage into the bowl.

You can fix the leak yourself if you take the time to inspect every part of the toilet. This includes the bowl as well as the area around the water supply valve. Sometimes a leaky toilet can simply be fixed by tightening the nuts and bolts. Sometimes, however, the whole toilet will need to be replaced.

Toilet leaks can quickly turn into a major problem. Leakage of water can cause serious damage to your bathroom and any other rooms below. Also, pests can be attracted to standing water in a bathroom. Water damage and all of the water that is lost over time can lead to a very costly problem.

For peace of mind, contact a plumber if you don’t have all the tools or are unsure about the source of the problem. Simple errors, such as not noticing cracks in the tank or tightening bolts enough, can cause more damage and headaches. Professionals can quickly assess the problem and fix it. You will then be able to use your toilet again in no time.

If your toilet leaks from the bowl and tank after it’s flushed, you can replace the tank to bowl gasket or bolts. However, if your toilet is leaking from the base after flushing, you’ll need to replace its wax ring.


A toilet wax ring, which is a thick wax that has been molded onto a plastic ring, provides a water-tight seal between the bottom of the toilet as well as the base of the toilet flange. It prevents sewer gases from escaping to the toilet and bathroom.

A closet flange, also known as a toilet, is a fitting that fits into the bathroom floor and connects the toilet to the drainpipe. The closet flange and toilet are connected by two bolts, securing them firmly to the floor with the help of the bolts.

The wax ring is placed between the flange of the toilet and the flange. A rubber gasket seal is an alternative to a wax ring. Rubber seals are easier to use than wax rings.

Leakage from your toilet’s basement ceiling or floor can indicate that the wax ring may not be sealing properly. The main cause is either a loose or broken toilet bolt, which causes the toilet to wobble.


A toilet tank-to-bowl gasket, also known as a “spud washer”, is a rubber gasket that provides a watertight seal between the toilet tank and bowl. It is usually installed outside the tank where flush water enters the bowl.

If the toilet leaks when flushed between its bowl and toilet tank, it could be a sign that the tank-to-bowl gasket has worn out, the tank bolts have become loose, or the flush valve is cracked. This is only a problem with two-piece toilets. To fix it, you will need to take out the toilet tank.

toilet leaks only when flushed


Materials you will need:

  • A wax ring/rubber seal
  • Bolts, nuts, and washers for the tank to bowl gasket
  • Adjustable wrench
  • Flathead screwdriver
  • Mini-hacksaw (optional)  
  • Putty knife
  • Sponge
  • Empty bucket
  • Rubber gloves
  • Newspapers
  • Old towel or rag

If your toilet leaks from the base after being flushed, you’ll need to take it out and replace the wax ring. A toilet that leaks from upstairs after flushing will be then detected by water in the basement or ceiling.

You must replace the wax rings or rubber gaskets in order to fix a leaky toilet. Let’s see how to replace toilet wax rings.


  • The shutoff valve for the toilet is located at the rear wall of your toilet. You will find it on the left side of the toilet at the rear wall.
  • Turn the valve clockwise. Pull the push/pull valve outwards if you want to turn off the water supply to the toilet tank.


  • In order to drain as much water as you can, flush the toilet by holding the lever down.
  • Take off the lid from the toilet tank and store it in a secure place. It is susceptible to cracking.
  • The toilet tank still has some water at its bottom. You can soak the water with the sponge and then squeeze it into the bucket.
  • Then, locate the water supply line that connects the shutoff valve to the tank’s underside. It is best to disconnect it. Before you use a wrench, always try to remove it from your hand.


  • Before you can remove the toilet, it is important to drain the water from the bowl.
  • Use the sponge to absorb the water and then empty it into the bucket. Always wear gloves.
  • After the bowl has dried, you will find the bolts on either side of the toilet. Sometimes, they have plastic caps. Use a screwdriver to pry the caps out.
  • Use the wrench to loosen the nuts and then take them out with your hands.
  • Use the mini-hacksaw in order to remove bolts that are rusty or won’t come off. Be careful not to damage the toilet body.
  • After you remove the nuts, take the toilet bowl in your hands and gently rock it to break the wax seal. Place it on its side on top of the newspaper.
  • Plugging the drainpipe with the towel/rag will prevent the sewer gases from reaching the bathroom.
  • Then, toss the old wax ring as you can’t reuse it.
  • Use a putty knife to remove any wax residue from the toilet outlet and the flange.
  • Examine the condition of the toilet flange. It will need to replace if it is damaged or worn out. It is easy to replace a toilet flange, especially if the toilet is off.


  • Make the wax ring slide into the outlet by simply leaving it out in the sun or dipping it to warm water for a few minutes.
  • Then, replace the bolts that you have cut by putting new ones in their place.
  • Be gentle when putting the wax in the toilet outlet.
  • Install the rubber gasket seal on top of your flange if you choose to use it. Then, hold it in place, it has holes that pass through the bolts.


  • Take the towel/rag out of the drain pipe.
  • To align the bolts with the holes in the toilet, lift the toilet from the flange. Call someone to assist you in alignment if you have the ability.
  • After the toilet is seated on the flange of the bowl, grab it with both your hands and rock it gently until the wax seal is fully engaged.
  • Attach a washer to each bolt, and then tighten the wrench.
  • In order to keep the toilet level, it is important that you tighten the bolts alternately. However, do not tighten the bolts too much. This could cause cracking in the toilet bowl.
  • You can remove bolts that are too high to the nut with a hacksaw.
  • Finally, place the caps on the nuts. Caps are for decorative purposes only.


  • Connect the water supply line to the tank.
  • Then, turn on the water shutoff valve to let the water flow into the tank.
  • Check the tank for leaks and flush it several times.
  • Place the lid on the toilet tank.

This repair will fix your toilet if it leaks after flushing. It is important to fix the toilet in a timely manner, especially if it’s wooden.

Bad odors can also be caused by a toilet that leaks from its base after it is flushed. This could be caused by urine, or a mixture thereof, leaking into the bathroom floor or subfloor.

It is up to you to decide whether or not to caulk around the toilet’s base. You can leave a small opening at your toilet’s back if you choose to caulk around it. If your toilet leaks, this will allow you to see the water on the floor.

toilet leaks only when flushed


The toilet tank to bowl gasket, also known as the spud washer, is responsible for leaking toilets that are flushed between their bowl and toilet tank. A wobbly toilet tank could also indicate that the gasket isn’t sealing properly, and water will leak from the toilet after flushing. You could also wear the gasket.

You will need to replace your toilet tank to bowl gasket to fix a toilet that leaks between the tank and bowl. The new toilet tank-to-bowl gasket includes toilet tank bolts, rubber washers, and metallic washers.

To replace the toilet to bowl gasket, you must first remove the toilet tank.


To replace the toilet bowl gasket, you will need to remove the toilet tank. You can tighten loose toilet bolts with a wrench, but you should replace them if they are rusty.


  • Turn off the shutoff valve to disconnect water from the toilet. This valve is located on the left-hand side of the toilet’s rear wall.
  • Turn the valve clockwise. Then, pull the push/pull valve outwards if it has one.


  • To flush as much water out as possible, flush the toilet tank by holding down the handle.
  • You can use the sponge to clean out the tank of water and then squeeze the bucket into it


  • You will see the bolt heads for the toilet tank when you look inside. These bolts are fastened underneath the toilet bowl using nuts.
  • Use a wrench to loosen the washers and nuts underneath the toilet bowl.
  • The tank will now be free. You just need to lift it off and then place it on top of a towel or rag.
  • You will find the toilet tank to the bowl gasket on the outside of the flush valve, covering the entire flush valve nuts. It is easy to slide it out.
  • Pull the bolts out of the tank’s interior and pull them off.


  • Place the new gasket in the place where the old one was, and make sure it covers the flush valve nut.
  • After putting the washers in, slide a metal wash and rubber washers into each bolt. From the tank’s interior, feed the washers and bolts into the holes.

Use the rubber washers to contact the toilet’s body. This will stop the tank from cracking if it is tightened too much. It also helps prevent leakage from the tank bolts.


  • Lift the tank, and then guide the bolts into the holes in the bowl. Then seat it on the bowl.
  • Install a rubber washer and a metal washer followed by a bolt. To tighten them alternately, use the wrench
  • Ensure that the toilet flapper was not moved during the repair. If you did, put it back in place.


  • Connect the water supply line to the tank. It is not recommended to use a wrench for tightening it.
  • Let the water flow into the tank by opening the valve.
  • Make sure to flush the toilet several times and inspect for any leaks between the tank & the bowl.

Once you are happy that the toilet isn’t leaking, close the lid and clean the area.

Wrapping Up

If you are able to fix a toilet that leaks when flushed, it can be done easily and at a very low cost. You can call a professional plumber if you fail to solve the problem.

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