Toilet Tank Leaks Only When Flushed

Toilet and plumbing leaks are some of the most common issues homeowners face. These issues can cause headaches, frustration, and serious damage if they aren’t handled properly.

Don’t panic If your toilet tank is leaking only when flushed. This issue is usually caused by something small and is easily resolved. Here’s what you need to know.

Why Does My Toilet Tank Leak When Flushed?

There are multiple causes for a toilet tank leaking only when flushed. Loose tank bolts and worn-out wax gaskets are common culprits. Hairline cracks, improper seals, broken closet flanges, or more severe issues could also be the reason. Most of these issues can be resolved in a few simple steps.

Types of Leaks

There are two main types of toilet leaks when flushed: leaks from the base and leaks in between the tank and bowl.

Toilet leaks from the base may require you to remove the toilet and replace the wax ring that’s causing the leak. If it’s an upstairs toilet, you’ll notice water on the ceiling on the floor underneath.

Leaks in between the tank and bowl are typically much easier to deal with. These issues are caused by loose bolts, gaskets, and worn-out parts. We’ll be covering how to fix leaks in between the tank and bowl in the following sections.

What Can I Do?

You will need to replace the toilet tank with a bowl gasket to resolve leaks between the tank and bowl after flushing. Typically, the gasket (or spud washer) is worn out and causes leakage. You’ll need to purchase a new toilet tank to bowl gasket beforehand that’s compatible with your toilet.

How to Replace a Toilet Tank to Bowl Gasket

Replacing a toilet tank with a bowl gasket is a fairly easy fix. You’ll need a new gasket, a wrench, a few other common tools, and some elbow grease to get the job done. Follow the steps below to begin.

Step 1: Drain the Toilet Tank

First, you’ll need to disconnect the water to the toilet by shutting off the valve. The shut-off valve is typically located on the left-hand side of the rear wall by the toilet. Disconnect the water by turning the valve clockwise or pulling it outwards if it’s a push/pull mechanism.

Step 2: Empty the Tank

Now you can empty the toilet tank by holding down the flush handle. Flush out as much water as you can. You can use a sponge or mop to get out any leftover water in the tank. Squeeze the excess water into a bucket or your sink.

Step 3: Remove the Toilet Tank

Now it’s time to remove the toilet tank. Inspect the inside of the tank; you should notice toilet tank bolt heads. These bolts are tightened underneath the toilet bowl with nuts.

Use a wrench to loosen and remove the nuts and washers from the underside of your toilet bowl. The tank should be free. Lift up the tank and place it on top of a towel, rag, or set of newspapers.

Step 4: Remove the Old Gasket

Now look for the toilet tank to bowl gasket. It should be located on the exterior part of the flush valve, and it should cover the entirety of the flush valve nut. Gently slide it out to remove it. If you don’t have a replacement gasket, you can take this one to the hardware store for a replacement.

You can also push and remove the two gasket bolts from the interior of the toilet tank.

Step 5: Replace the Toilet Tank with Bowl Gasket

Now you can replace the toilet tank with a bowl gasket. Gently slide the replacement gasket where the old gasket was located. Ensure it completely covers the flush valve nut.

Glide a metal wash into the bolts provided, followed by the rubber washers. After, insert the bolts and washers into the holes from the interior of the tank.

Ensure that the washers that touch the body of the toilet are made of rubber. Rubber will prevent any cracks if they’re tightened too much. Rubber washers will also prevent any leaks from the tank bolts. Be sure to follow all the instructions and guidelines on your gasket kit.

Step 5: Install the Toilet Tank

Now you can reinstall the toilet tank from earlier. Insert the bolts through the holes in your bowl. You may need to insert the bolts before you place them on the bowl. Ensure the tank is properly set.

Take a rubber washer, followed by a metallic washer, then a nut into each bolt. You can use a wrench to tighten them, alternating between them.

Ensure the toilet flapper and the fill valve didn’t shift around. Put them back into place if they happened to move around.

Step 6: Reconnect the Toilet Water Supply

Finally, it’s time to reconnect the water supply line to your toilet tank. Don’t use a wrench to tighten it. Reopen the shut-off valve allowing the water to fill the empty tank.

Try flushing your toilet a few times to check for leaks. Your problem should be resolved if a worn-out gasket was the issue. Once satisfied, you can put the toilet tank lid back in place and clean up your work area.

Why Is My Toilet Tank Leaking Only When Flushed?

Leaks between the toilet tank and bowl when flushed are typically caused by loose bolts and worn-out gaskets. The issue can be easily resolved by replacing the tank with a bowl gasket following the steps above. If replacing the gasket doesn’t resolve your issue, you may have more severe problems and need professional plumbing services.

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