Toilet Leaks When Flushed

Toilet leaks are one of the common plumbing issues you have to encounter. At times, when a layman doesn’t have professional plumbing help, this can become a headache.  For instance, the prevalent leakage issue you might encounter is toilet leakage when flushed.

So, what do you think? What might be its causes and what can be done to fix it?  Shortly speaking, the common causes of toilet leakage when flushed include damaged or cracked bowl gasket, loose bolts, fractured wax ring, and hairline cracks in the toilet bowl.

Further, in the article, we will cover how you can identify the source of leakage, then find out the cause of leakage, and finally, how you can fix it.

Identification of Leakage Source

To fix the leakage problem, first, you need to identify the source of leakage in the toilet.  Is the leakage source in between the tank and bowl? Or is it leaking around the base?

So, if you diagnose that the toilet leaks from the area between the tank and bowl, then the culprit is the bowl gasket. In the other case, if the toilet leaks around its base, then the wax ring is at fault or the bolts are loose.

Sometimes, the hairline cracks in the toilet’s tank also cause the tank water to leak. In that case, the toilet bowl doesn’t retain its level, and secondly, you smell a foul odor in the washroom.

Since we have identified the causes, now let’s talk in detail about how you can fix the problem in each case.

Cause # 1: Cracked Bowl Gasket/ Spud Washer

A spud washer, also known as a toilet tank to bowl gasket, is a rubber gasket that seals the toilet tank from the bowl. It is often located on the exterior of the flush valve, near the point where the flush water exits the tank and enters the bowl.

Kohler 1-piece screw gaskets and tank to bowl seal

Over time, the gasket wears out and when that happens, the toilet starts to leak in-between the tank and the bowl. However, this only happens if you have a two-piece toilet. To fix the issue, you need to remove the toilet tank and install a new bowl gasket or spud washer.

How to replace the cracked bowl gasket?

Replacing the gasket is a difficult task. You need to carefully follow the mentioned steps to complete this job successfully.

Step 1: Cut off the water supply to the toilet 

First, turn off the shut-off valve, which is usually located at the rear wall facing the toilet tank. Turn the valve the clockwise to close it.

Step 2: Make the Toilet Tank Empty

Flush the water inside the tank. Take off the tank’s lid. Clear the residual water; soak it up with the sponge and dump it into the empty bucket.

Step 3: Remove the toilet tank loosening the bolts inside the tank

Once you clear the tank, you will find the bolt heads at the bottom of the tank. Actually, they are tightened with nuts outside, underneath the tank.

Using a wrench, loosen the nuts and then remove them. Now, the tank is free. Take it out and place it in a clean place.

Step 4: Replace the old gasket with a new one

The bowl gasket is found on the outer part of the flush valve covering the entire flush valve nut. Just slide it out and insert a new gasket in its place.

Step 5: Re-install the tank

Elevate the tank and insert the bolts through the toilet bowl’s holes. Carefully ensure that the tank sits nicely on the bowl.

In each bolt, place a rubber washer first, then a metallic washer, and finally a nut. Alternately tighten them using the wrench.

During the repair, make sure the toilet flapper and fill valve did not shift.

Step 6: Turn on the water supply

Reconnect the water supply you removed from the tank. Turn on the shut-off valve by rotating it counterclockwise. Place the lid on the tank.

So, if the bowl gasket was the cause of leakage, this repair would have fixed the problem.

Cause # 2: Worn-Out Toilet Wax Ring

When the wax ring is fractured, the toilet leaks around the base. Because the wax ring is unable to seal the flange with the drain pipe.

A toilet wax ring is a solid wax band-shaped upon a plastic rim that makes a watertight seal between the toilet’s bottom and flange’s toe.  It is actually sandwiched between these two parts. Additionally, it inhibits sewage gases from entering the bathroom and the toilet.

Speaking of toilet flange, it is a round pipe fastened to the toilet floor, connecting the toilet to the drain pipe. The flange and the toilet are connected by two bolts, anchoring the toilet firmly to the floor.

Crushed wax ring broke at the back


To fix this problem, you need to take apart the whole toilet and replace the wax ring that is the source of leakage.

How to replace the worn-out gas ring?

To replace the worn-out gas ring, follow these mentioned steps properly.

Step 1: Close Shut-Off Valve

Locate the shut-off valve for the toilet. It can be found predominantly on the left side of the toilet’s back wall. This valve should be turned clockwise.

Step 2: Discharge the water from the tank

Next, flush to drain all the water inside the tank. Take off the tank’s lid and see if any amount of water is left at the bottom. If there’s any water left, soak it up with the sponge and squeeze it into an empty bucket.

Step 3: Disconnect the water supply to the toilet

Locate the water supply line that connects the shut-off valve to the tank’s underbelly. Unplug it.  Try to disassemble the line with your hands. If that doesn’t work, you can use a wrench.

Step 4: Remove Water from Toilet’s Bowl

Since you flushed the tank in the second step, so the toilet bowl still contains water. So, before removing the whole toilet, you need to get rid of this water. Because removing a toilet filled with sewer water will only make things messier.

Since the water is dirty, put on gloves and take a sponge. Soak up the sponge in the bowl’s water and dump it into a bucket. Do this activity until the bowl becomes dry.

Step 5: Dismantle the toilet

Since the water has been drained, the tank is now clear. Locate the bolts on the sides, at the bottom of the toilet. In some toilets, the bolts have plastic caps on them. Pull off the caps using the screwdriver.

Then, make the nuts lose with a wrench. Now, you can take out them easily with your hands.

In some cases, the bolts become rusty due to moisture and water. In that case, cut the nuts off with a hacksaw.  Be cautious; don’t cut the body of the toilet.

Once you remove the nuts, grab the toilet bowl firmly with both hands and slightly shake it to thoroughly disintegrate wax seal.

Place the toilet carefully on one side. And insert a towel into the drainpipe to avoid the spread of sewer gases.

Step 6: Install the new wax ring/rubber gasket

Take out the old worn-out wax ring, and inspect the toilet’s flange. See if it needs replacement because you can do it easily at this stage.

If you want that the wax ring fits easily, then dip the ring in the warm water.

Install the ring on the top of the flange.

Step 7: Re-install the toilet

Elevate the toilet over the toilet flange; gently lower it to align the bolts with the toilet’s two holes. You will need another person to help you with the proper alignment.

Holding the toilet by the bowl with both hands, shake it and gently push it down to fit in the wax seal.

Insert the bolts with washers in their respective places and tighten them with a wrench.

Step 8: Restore the water supply

Reconnect the water line you removed from the tank, and turn on the shut-off valve. Place the lid of the tank.

Cause # 3: Loose Bolts

The loose bolts of the toilet also tend to disturb the wax ring and cause leakage through the base. So, if you feel that the toilet isn’t properly fixed in its place, it does shake when used. That means the bolts are loose and they have misaligned the wax ring.


You will have to repeat the same procedure as we mentioned in the case of wax-ring. The toilet needs to be removed and fixed again.

Cause # 4: Hairline Cracks in the toilet Bowl

Apart from a worn-out gas ring, the water around the toilet’s base may also be due to the hairline cracks. In that case, you will notice tiny cracks in the toilet bowl when you examine it carefully.

How can you fix the Hairline Cracks?

Now, the first two causes of leakage can be addressed by replacing the gasket, tightening the nuts, or replacing the gas ring. But in this case, the cracks cannot be fixed. The only way to fix is to install a new toilet. And that I guess is simple compared to what you have already learned.

We hope that you have got an idea of how you can fix a toilet that leaks when flushed. By following our steps, you can diagnose the cause of the fix, and repair it by yourself. However, if you believe that you can’t do it yourself or your attempt to fix failed. Then, you can always seek the help of an expert plumber.

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