Toilet leaking from tank when flushed [How to fix?]

A toilet leak is one of the most common plumbing problems that homeowners experience at home. If your toilet is leaking every time you flush, there’s no need to panic. However, you should identify what’s causing your toilet tank to leak.

Some of the main reasons why your toilet tank may leak when flushed are due to a worn-out or faulty bowl gasket, loose tank bolts, or a cracked flush valve. Therefore, you should inspect all of these things before making any conclusion.

The good news is that you can fix all of these problems yourself if you have all the needed tools. And if you don’t have the tools or time to fix your leaking toilet tank, it’s best if you call a professional plumber. You can also get a tankless toilet such as Toto G400 dual flush toilet or Kohler Veil smart toilet to avoid this issue.

The easiest thing to fix is loose bolts. If the bolts on the tank are loosened, you can quickly fix them by tightening them. But if you have a worn-out bowl gasket or cracked flush valve, it would be best if you contact a professional plumber.

Regardless of what’s causing your toilet tank to leak, it would help if you fixed it immediately. If you don’t attend to a toilet leak, it can cause severe damage to your bathroom, which may become costly in the long term. That’s why you need to repair them right away.

In this guide, we’re going to direct you on how to repair your leaky toilet tank every time it’s flushed.

How to fix a toilet leaking from tank when flushed

If you don’t have a one-piece toilet and your toilet has been leaking every time you flush it, you can fix it by inspecting it first. Depending on the cause of the leakage, here’s how you should fix the leaking toilet tank:

How to fix loose bolts that hold the tank to the bowl

Toilet leaking from tank when flushed

A separate tank and bowl normally accompany two-piece toilets. These two parts are usually held together by bolts. Most of the toilets feature three bolts that keep the tank in place on top of the bowl. So, if the bolts are not appropriately fixed or are loose, the water in the tank may find its way into the bowl even after flushing.

Related article: Check The Possible Causes and Solutions of Toilet Whistling

You will have to disassemble your toilet and use a wrench or screwdriver to tighten the bolts in such a case. Besides, you should also screw the water supply line tightly. Nonetheless, it would be best if you avoided over-tightening the bolts as this can cause more damage to your toilet.

If you notice that the water is still leaking when you flush, you should inspect the bowl gasket.

How to fix a worn out or damaged bowl gasket

Toilet leaking from tank when flushed

 As stated earlier, one of the leading causes of water leaking from the toilet tank to the bowl after flushing is a worn-out or damaged bowl gasket. Also known as the spud washer, a damaged or worn-out bowl gasket can let water into the toilet.

To fix this issue, you will be required to replace the lousy bowl gasket with a new one. Note that a new spud washer comes with toilet tank bolts, rubber washers, and metallic washers. Here are the steps to follow:

Step 1: Drain the toilet tank

Toilet leaking from tank when flushed

Begin by switching off the water at the shut-off valve. The shut-off valve is usually located at the back of the toilet and on the left-hand side. Turn the valve clockwise.

Step 2: Empty the water into the toilet tank.

Empty the toilet tank by flushing the toilet. To get rid of a lot of water, hold the handle down until all the water is gone. Use a microfiber cloth or sponge to drain the remaining water in the tank.

Step 3: Remove the toilet tank from the bowl

Toilet leaking from tank when flushed

The next step is to disconnect the toilet tank from the bowl and check the flushing system. When you take a quick look into the empty tank, you will see the tank bolt’s head. They are usually tightened from below the toilet bowl with nuts. You can loosen and remove the nuts with the help of a wrench.

When you’re done loosening the nuts, you can lift off the tank and place it on a rag or cloth. You will see the toilet bowl gasket on the outer part of the flush valve covering the whole flush valve nut. Push and get rid of the two bolts from the inside of the tank. If the bolts are corroded, don’t reuse them.  

Step 4: Replace the bad bowl gasket with the new one.

Install the new bowl gasket where the old one was positioned. Place the new bowl gasket where the old one was positioned. Make sure the new gasket covers the whole flush valve nut. Next, slide the metal wash into each bolt and follow it with the rubber washers. Avoid over-tightening the washers as it can cause damage. Also, ensure the washers are made of rubber and not plastic.

Step 5: Install the toilet tank

Toilet leaking from tank when flushed

When you’re done replacing the old bowl gasket with the new one, return the toilet tank in its place. Start with placing a rubber washer, then a metallic washer, and finally nuts into each bolt. Tighten them, but don’t over tighten. Furthermore, ensure that the toilet flapper and fill valve sit appropriately in position and do not shift.

Step 6: Reconnect the water supply.

Toilet leaking from tank when flushed

To complete the new bowl gasket installation, reconnect the water supply line at the back of the toilet. You can then turn on the shut-off valve. When the toilet tank is full, you can test and see if the water doesn’t leak from the tank after flushing the toilet. This repair should fix the problem.

But if the problem persists, you should attempt this final method.

How to fix a toilet with a damaged or faulty flush valve

Toilet leaking from tank when flushed

Another thing that can make your toilet leak after every flush is a bad or damaged flush valve. If the flush valve is damaged or cracked, it will allow water to run from the toilet tank to the bowl. Also, it can make the toilet take a longer time to fill up. Besides, the toilet can have a weak flush.

Related article: Why Is Your Toilet Flushes Slowly When You Flush?

Nevertheless, all of these can be fixed and have your toilet running smoothly. The first thing to check if you suspect that the toilet is leaking because of a bad flush valve is the flapper. If your toilet’s flapper is not sitting properly, cracked, or damaged, it will allow water to escape from the tank. The best choice is to replace it with a new flapper. Before you remove the flapper, inspect it and ensure it’s the cause of the leakage.   

Summary

If you’ve had a two-piece toilet and it leaks from the tank every time you flush, you can inspect your toilet and fix the problem. The main reason why your toilet may have a leakage is because of a bad flush valve, worn-out bowl gasket, or loose bolts.

You can follow the procedures that we’ve discussed above to carefully and adequately fix your toilet. But if you don’t have the necessary tools and time to do it, you can always hire a professional plumber to assist you out.

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