Toilet Leaks When Flushed — Here’s How to Stop It

No one likes a leaky toilet. Not only is it an inconvenience that keeps ruining bathroom floors, but it’s also wasting water and costing you money over time.

If your toilet leaks when flushed, it probably has a worn-out wax ring or tank-to-bowl gasket. The other two causes include leaky toilet tank bolts and loose water supply hoses.

The good thing is that you can fix a leaky toilet alone. There’s no need to call a plumber for this one — all you need is a set of simple tools, spare time, and some elbow grease.

What Causes Toilet Leakages?

When you notice a toilet leak, the first task is to identify the cause. Toilet leakages occur for several reasons, but four of them are specific for post-flushing leaks. 

A Broken Wax Ring

The wax ring is a round piece of wax that seals the toilet to the flange. It’s a connection point that enables the bowl to sit tightly on the flange. The wax seal also prevents toilet leaks, but it is prone to wear and tear.

When the ring is damaged, your toilet starts leaking at the base. In such circumstances, you’ll start seeing puddles around the toilet base and near the bowl.

A Damaged Tank-to-Bowl Gasket

A toilet tank-to-bowl gasket is a waterproof sealant between the toilet tank and the toilet bowl. It controls the supply line leading the water from one part to the other.

However, the gasket can break over time because of frequent use. A faulty or worn-out gasket can be a big problem because it creates a mess in your bathroom. Sooner or later, it will disable the system to make a leaky toilet.

A Loose Supply Line Nut

A toilet water supply hose is a metal tube that brings water from the plumbing system to the toilet tank. The hosepipe stretches from the shutoff valve to the toilet tank, connecting to its fill valve below.

A thread metal nut is what’s holding the water supply line firmly attached to the tank. The nut will probably loosen after a few years, causing a water leak after each flush.

Outdated Tank Bolts

Toilet tank bolts are a couple of screws holding the entire structure of the tank. Most toilet tanks have two bolts at the bottom — one on each side. The bolts corrode or wear out, especially if you’re using bathroom cleaners with strong chemicals.

In such cases, they will weaken and break, allowing the tank to shift. This will cause a leak at the bottom of the tank and below it. You’ll be able to see the pooling of water on your floor once you notice this problem.

What to Do if Your Toilet Leaks When Flushed? 4 Solutions

Now that you know four problems that cause toilet leaking, you should think about fixing them. Before that, remember to gather the usual DIY repair tools:

  • Buckets, dry towels, rubber gloves, and sponges
  • Adjustable pliers and wrenches
  • Bolts, nuts, a wax ring, or a gasket
  • Putty knife and flathead screwdriver

This is enough to get you going, so let’s focus on the most important part of the process. Here’s what you can do to prevent the toilet leak after flushing.

Replace the Wax Ring

If the water-tight seal beneath the bowl gives you headaches, the only option is to replace it. Things can get a little messy, so be ready to do some dirty work in your bathroom. We’ll go through each step separately:

Step 1: Close the Shutoff Valve

You have to close the shutoff valve because it stops water from entering the toilet tank. It’s a small valve behind the toilet — the water supply line connects it to the toilet tank. All it takes is to turn the valve clockwise to close it.

Sometimes the shutoff valve won’t shut off because it’s stiff and rusty, so you can use penetrating oil like WD-40 to loosen it. After that, you can turn the knob with your hands or pliers.

Step 2: Empty the Toilet Tank

You need to empty the tank before removing it. The water supply is off, so you can flush the toilet and watch the water disappear. After that, it’s good to remove excess droplets from the tank.

Open the tank cover with a flathead screwdriver and clean the bottom with the sponge. The tank is now completely dry and ready for removal.

Step 3: Remove the Toilet

Now it’s time to remove the entire toilet from its base. Start with the tank —unscrew the bolts from the bottom (turn them counterclockwise) and grab the tank with your hands. An empty tank is lightweight, so you won’t have a problem lifting it.

After that, you must remove the bowl. It also has a pair of bolts at its base, so you need to unscrew those as well. You’ll notice that the bowl is wobbling, which means you can lift it and remove it from the flange.

Step 4: Remove the Old Ring and Install a New Item

When you remove the bowl, you’ll see the old wax ring on top of the flange — it’s a brown and sticky substance. Remove the remnants of the wax seal with a putty knife. After that, you can install a new wax ring.

Place it on the flange and press it to sit tightly against the flange top. The new wax ring will set a solid foundation for your toilet bowl and prevent toilet leaks after flushing.

Step 5: Reinstall the Toilet and Open the Water Supply Line

Finally, you can reinstall the toilet by setting both elements — the bowl and the toilet tank. Use the same bolts and screw them clockwise. When you do that, you can turn on the water supply by opening the water supply valve.

Change the Gasket

Changing the gasket is easier because you don’t need to remove the toilet bowl. Once again, we’ll breeze through each step individually:

Step 1:  Close the Shutoff Valve 

The first step is the same for changing the gasket, so you’ll need to close the shutoff valve before fixing the toilet. We already explained how to do it — turn the knob clockwise with wrenches, and that’s it. 

Step 2: Empty the Toilet Tank

The second step is also the same, which means you’ll need to remove water from the toilet tank. Doing it is easy — flush the toilet and pick the remaining water with dry towels of a sponge.

Step 3: Remove the Tank

Remove the toilet tank by unscrewing the bolts from the bottom (turn them counterclockwise). Take the tank with your hands and put it on the bathroom floor — place a dry towel beneath it.

When you remove the tank, you will clearly see the flush valve with a rubber gasket on it. This is where the real fun starts.

Step 4: Remove the Gasket and Put a New Item

Removing the gasket is simple as you can snap it off with your fingers. Another option is to use a flathead screwdriver, but you probably won’t need it. As soon as you remove the old gasket, you can set the new model.

The new gasket has to cover the entire flush outlet, so make sure to position it properly. After that, you can put back a couple of bolts and support them with rubber washers — it prevents cracking when you screw the bolts too tightly.

Step 5: Reinstall the Toilet Tank

Now that the gasket is fully operational, you can reinstall the tank. You probably know the drill already — set the tank, screw the bolts by turning them clockwise, and cover the tank with the lid.

The next task is to open the shutoff valve and let the water flow into the tank. After that, you can flush the toilet and check whether it’s leaking. The new gasket should prevent it.

Tighten the Supply Hosepipe

Solving the third problem is very simple as you only need to tighten the supply hosepipe. First of all, grab it with your fingers and turn the threaded nut clockwise — twist the nut as far as you can.

Secondly, you should use wrenches to strengthen the grip. Be very careful because the housing might break — don’t use full force, but rather rotate wrenches gradually. If you do it gently, the tool won’t make cracks in your toilet tank.

In case the metal hose is damaged, then the only solution is to replace it. Here’s how:

  • Unscrew the nuts connecting it to the shutoff valve and the tank
  • Remove the old water supply hose
  • Insert the new metal hosepipe
  • Turn the nuts clockwise to secure the hose

Replace Old Tank Bolts

Toilet leaking sometimes indicates old and rusty toilet tank bolts. Worn-out bolts can become loose and allow water from the tank to spill and flow down the toilet. Every time you flush, bolts will let excess water through the holes and cracks.

Fortunately, this is another problem you can solve with ease. Let’s see how:

Step 1: Remove the Toilet Tank

You already know how to remove the toilet tank — close the water supply line, remove the supply hose, flush the toilet, and unscrew the bolts. Put the tank in a safe place on the floor to avoid stepping on it as you move around the toilet.

Step 2: Throw Old Bolts and Washers

Your goal is to install new bolts and washers, so remember to dispose of old ones. If the old bolts are too rusty to unscrew, we suggest using WD-40 for loosening metal components.

Leave the penetrating oil to do its job for five minutes, and unscrew the bolts. WD-40 will make it easy to turn the screws counterclockwise, so you’ll do it in a minute.

Step 3: Set the New Bolts

Installing new toilet tank bolts is the next step. Put them in the holes at the bottom of the tank and twist them clockwise. Turn the bolts until you feel that they sit tightly against the tank — don’t overdo it because the plastic tank may crack due to excess force.

Step 4: Reinstall the Tank and Open the Water Supply

The last task is to reinstall the tank and open the shutoff valve. Finally, check if there are any leakages once you open the shutoff valve — use a paper towel to inspect each bolt and every corner of the tank.

The Bottom Line

When you notice a toilet leak after flushing, you should prepare to replace the wax ring or change the gasket. The only alternatives are leaking tank bolts and water supply pipes.

In this post, we showed you how to solve four leaky toilet problems. Follow our step-by-step instructions, and you will handle it very soon!


When I flush my toilet, it’s leaking from the bottom?

If your toilet is leaking from the bottom when you flush it, the reason is a broken ring. It’s a wax part that helps the bowl stand firmly on the ground, so you’ll need to replace it to prevent future leaks.

This is not the simplest bathroom project because you’ll need to remove the entire toilet. You’ll find the old ring under the toilet – remove it and install the new model to eliminate water leakages. 

How can you tell if a toilet wax ring is leaking?

You can tell that the ring is leaking by puddles on the floor around the toilet base. Besides that, the toilet probably smells like urine. If you don’t have a leaking toilet tank, the ring is old and not sealing the toilet base.

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