Why Is My Toilet Leaking Through The Floor? (Explained)

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Your toilet leaks through the floor because the wax seal that joins the toilet to the bathroom floor is broken or loose. Over time, this seal can loosen or have a defect, causing water to leak through and flood your floor. You may notice water stains on your ceiling if your bathroom is upstairs. 

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A leaking washroom can be a nightmare. Imagine coming home from work after a long day only to find your entire living room flooded with toilet water. It would not be a good sight, especially if you left everything intact.

There are many reasons why your toilet may be leaking through the floor. While some of these reasons might be structural, it is essential to find out the core reason why.

A leaking toilet is unsafe to use. It is a health hazard since toilet water is full of pathogens and disease-causing bacteria. You may also slip and fall, injuring yourself in the process.

Read on to find out more information on why your toilet is leaking and what you can do about it.

How Do I Know If My Toilet Is Leaking From Underneath?

The first tale-tell sign that your toilet is leaking through the floor is water on your toilet floor. Normally, your toilet floor is dry and clean, then you find water seeping through your rugs all of a sudden. This is a sure sign that your toilet is leaking.

Once you notice some water on your bathroom floor, even when you are sure every tap is closed, investigate to find out where the leak is coming from. It may not be the toilet, but here is how to find out if your toilet is leaking.

Most common toilet leaks come from the base of the toilet bowl. However, sometimes, these leaks may come from another place. Some notorious toilet leak sources include:

The water supply knob

This is also called the water supply valve. This hose comes out of the wall at the back of the toilet. Sometimes, this valve may come loose or fall off, resulting in leaks. If not fixed promptly, water may gush out.

Fill Valve Inlet

The leak might come from the fill valve inlet. It is at this valve that the freshwater pipe is linked to the main tank. It is located at the bottom of the water tank.

If this valve is faulty, you may have leaks. It’s vital that you keep this line dry since the seal nuts and bolts may come loose and fall off when wet.

Flush valve seal

Water will leak out of the tank if your flush valve seal is not correctly and tightly bolted. This seal connects the water tank to the toilet bowl. If it is loose, water will leak. Such leaks are often mistaken for leaks happening at the base of the toilet.

This kind of leak occurs at the flush valve seal, and the water trickles down the tank to the base, making it look like the leak is coming from the toilet base.

Toilet base leaks

These are the most common leaks and often lead to flooding on the floor. Even then, you still need to find out and confirm if that water is actually coming out of the toilet’s base.

If the floor around your toilet base is soft and feels spongy or squishy, it could be water. You may also notice tiling peeling off or water stains and streaks on the floor.

Such signs should compel you to look for leaks at the toilet bowl base as soon as possible.

To do this, you need to check if the toilet bowl is loose since water will leak from an open toilet.

Gently push the toilet, rocking it from side to side. If the bowl is steady and immovable, then the leak must be coming from elsewhere. If the bowl rocks from side to side, then water could be leaking from this base.

Toilet base leaks come as a result of faulty seals. If the seal on your base is broken or loose, water will seep through. This seal needs to be watertight. Regardless of how posh your toilet bowl looks or how fancy the water tank is water will leak and flood your bathroom floor if you don’t use a quality seal.

Do you want to find out why your toilet is leaking from the base? Tag along.

Why Is My Toilet Leaking Through The Floor?

Your toilet is leaking through the floor because of a defect in the plumbing system. To get a clear picture, it is best to understand how a toilet plumbing system functions and works. Here is how it functions.

A toilet has two major parts; the bowl and the tank. The work of the bowl is to hold water. It also connects to the toilet drain and disposes of waste and water.

On the other hand, the tank has reserve water used to fill up the toilet bowl. It is usually found behind the toilet bowl and contains the devices used to flush clean water into the toilet bowl. This water is also used to refill the tank.

One gadget used to flush clean water and refill the water tank is called a ballcock. This part is connected to the main water supply and serves to control water delivery to the tank. When the water level in the tank drops down the bowl, say when you flush, this pressure will cause wastewater in the bowl to go down the drain.

When this water drops, the pressure gauge or the ball will sense the void, prompting the ballcock to refill the water tank. This is how the old model water closet fills up with water. The modern ones where you press a button to flush get their water from the mainline.

When flushing an old model water closet, water from the reserve tank usually drains into the bowl through a device known as the flush valve. This valve is closed with a rubber stopper called a tank ball, flush valve seat ball, or the newer, very efficient flapper ball once you trip the lever.

In the construction world, both the flapper and the valve are called the flapper valve. The rubber flapper will lift off the valve when you trip this lever, and water flows into your toilet bowl. A flush valve is a small device, about two inches in diameter.

It is ball-shaped, the only ball-shaped section of the flapper. Looking closely, you will notice that this flapper pivots to the vertical overflow line usually located next to the valve. There is a small chain connecting the trip lever and the flapper.

Most traditional toilets had stoppers rather than flappers. Flappers are better in that they don’t have many parts that need to be strung or hanged up. This minimizes the chances of water leaks.

Now that you have an idea of how your toilet functions, albeit vague, you can now understand why your toilet leaks and how you can fix them.

Sometimes, the leak can be so bad it may seep through your ceiling. At this point, be prepared to repair not just your toilet but your ceiling as well since this water will cause water stains and streaks. That said, here are a few reasons why the water in your bathroom is leaking through the floor. Remember, faulty toilet parts almost always cause toilet leaks.

Stuck/Trapped Flapper

As earlier mentioned, your toilet has a rubber flapper with a seal that helps keep water in the toilet tank or reservoir. This part lifts to allow water to flow from the water tank into the toilet bowl whenever you flush the toilet.

Sometimes, the flapper might fail to seal the tank effectively. It might get stuck. Quite frequently, the flappers might get stuck in an open position to enable water to flow continually into the toilet bowl. When this happens, you will notice the handle of your toilet rigid or too loose.

You will also see some water coming out of the water tank since the flapper isn’t working well to prevent the water from running over and, as a result, a leaking toilet.

To find out if your toilet flapper is stuck, lift the toilet tank lid off and check. The first tell-tale sign of a stuck flapper is a rigid handle.

Damaged/Faulty flapper

Sometimes, the flapper might not just be stuck but damaged. This may happen after repeated cases of it being stuck in an open position. This part might look like a small, simple part, yet it plays a huge role.

If it breaks, cracks, or loses shape, you are likely to experience leaks. When this happens, you may hear the annoying sound of water continuously trickling from the tank to the bowl, even before you flush.

This is called a silent leak and, in most cases, quite challenging to detect and repair. A faulty flapper will cause your water tank to overflow and consequently flood your toilet floor.

Faulty supply line

As mentioned earlier, water goes into the reservoir tanks via a cold-water supply pipe. This line is usually closed and sealed when working optimally to prevent water from leaking out and air from entering in.

Nevertheless, over time constant water pressure can cause this tube to crack or even break. When this happens, your toilet will leak to the floor. When the line bursts, your whole toilet area will flood.

Damaged toilet water tank

A damaged water tank will cause leakages and ultimate flooding. Your tank may be cracked or broken, causing leaks. In such a scenario, ensure you repair or replace your toilet as soon as possible. You don’t want toilet water flooding your entire house when the crack on the tank finally gives in.

Damaged toilet bowl

This may be the worst reason why your toilet is leaking through the floor. This is because water from the toilet bowl isn’t just water but a mix of water and waste.

A damaged toilet bowl should be fixed as soon as it is damaged. Quite often, repairing toilet bowls isn’t recommended. You have to replace the whole toilet.

Toilet bowls are made of porcelain, and water (and waste) will likely seep through any small crack present. Glue and putty will not seal these cracks, especially if the bowls are made of porcelain or ceramic materials.

That is why plumbers and those in the construction industry advise that if your toilet is damaged, especially at any structural part, it is best to replace the whole toilet.

Corroded Fill valve

Your toilet may be leaking through the floor because of a corroded, damaged, or rusted fill valve. The fill valve controls the amount of water going into the reservoir tan. It ensures that just the right amount of water goes into the tank, hence preventing overflow.

If this valve is damaged, there will be no way to control the amount of water going into the water closet. Water will overflow and flood the floor. When this happens, it is recommended to shut off the water from the mainline as you seek professional plumbing assistance.

Faulty connectors

Your toilet, just like any other plumbing fixture, has numerous connectors. Nonetheless, when these connectors are faulty, broken, or loose, water will leak and flood your bathroom floor. Ensure you check your connectors frequently to ensure no leaks are coming from faulty connectors.

Whenever you find water on your washroom’s floor, check on the above sources to determine where the leak is coming from. Once you’ve determined the cause of the leak, you can now go ahead and try to fix it or call a professional plumber to fix it.

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How To Fix The Leaking Toilet?

A leaking toilet needs to be fixed as soon as you detect the leak, lest you end up with a flooded flour. Plus, it is cheaper to repair a faulty toilet part early than replace the whole toilet because of neglect.

Fixing a leaking toilet is easy, depending on where the leak is coming from. Some leaks may be coming from the base of the toilet, while some from other various parts. Some repairs will need you to engage professionals.

Here is how to fix a toilet that leaks from the base.

Equipment needed:

  • Wrench
  • Channel-lock plier
  • Mini hacksaw
  • Tube and tile caulk
  • A pair of work gloves
  • Putty knife
  • Toilet tank drip tray
  • Insulation panels
  • Wax rings
  • Floor bolts

Before you start repairing, you will have to deal with condensation. When water floods your bathroom floor, humidity may cause it to condense. This is evident if you notice tiny droplets of water at the base of the toilet water tank.

This is known as sweating. Most porcelain materials do so. To reduce condensation, check for leaks from the flappers. If the flapper is leaking, replace it with a new one. Otherwise, use the toilet tank drip tray to collect condensation.

This will help prevent it from flooding the floor.  Water coming out of the base of your toilet may also mean that the toilet bowl is loose, and you need to tighten the floor bolts.

To do this, remove the floor bolt plastic caps on either side of the toilet bolt. Check for any signs of wear on both the nuts and the bolts. If they are rusted, then you need to replace them with new ones.

Using the adjustable wrench, tighten the nuts on all the bolts. While at it, flush the toilet to draw the bowl to the floor. This helps you tighten the bolts even further.

Your toilet may leak because the wax ring covering the toilet’s base is coming off and needs replacement. You can purchase generic wax online since it fits most toilet bases. Here are simple steps to help you fix a faulty wax ring.

  1. To replace the wax ring, first cut off the water supply from the mainline. You can do this by closing the fixture shutoff valve situated underneath the left side of the tank.
  2. Flush the toilet to empty it, then use a bucket and sponge to soak up all the remaining water.
  3. Cut off the fill valve by unbolting the nut that holds the water supply line to the fill valve. It is found under the toilet tank.
  4. Unclip the caps covering the floor bolts on the base of the toilet, then loosen the nuts. You may find these nuts and bolts have rusted and consequently fused. Use your hacksaw to separate them.
  5. Slowly lift the toilet bowl away from the drain and set it aside. If it’s too rigid to move, push it gently from side to side to help break the wax seal.
  6. The old wax ring may be hard to scrape off, so use your putty knife. Be sure to remove all wax, especially those that stick on the drain opening. Use gloves while working. You are likely to encounter build-up grime and sometimes waste. Clean out the drain pipe and also the floor bolt holes.
  7. Position the new wax ring over the drain, with the plastic cone facing downwards. Ensure the bolts are also well fixed on either side of the drain flange.
  8. Reposition the toilet bowl back on the drain pipe and ensure that you press it onto the wax ring to create a watertight seal. Use your wrench to tighten all bolts and nuts.
  9. Reconnect the water supply, then test for any leaks.

Ensure you tighten the bolts well enough, so the toilet bowl is stable.


A leaking toilet is not only unsightly but also hazardous. When you notice signs of a leak, ensure you fix it as soon as possible to minimize flooding and also the need for you to replace the whole toilet.