Water Leaking Under Toilet Base When Showering: The Expert’s Solution

Water Leaking Under Toilet Base

You turn on the shower faucet to enjoy your shower and see the toilet base flooding. The scene is both scary and frustrating. When you see such an overflow of water in the toilet base, you need to act first and solve it. Always start by inspecting the water toilet base for overflowing.

It is crucial because without finding the reasons for water leaking under the toilet base when showering. Usually, leaky water lines, loose wax rings, t-bolt, or worn-out and clogged drain lines cause the problem. Also, the loose flange and cracked toilet bowl will cause overflowing of the toilet base.

Depending on the water leakage reasons, you need to act differently. It will allow you to fix the water leakage problem and enjoy hygiene.

Why Is Water Leaking Under Toilet Base When Showering?

We all love taking a shower in the morning or returning from work. It relieves us from tiredness and rejuvenates us. However, the problem starts when the toilet base leaks to overflow the floor.

It decreases the hygiene of the toilet. Also, you may experience a bad odor due to the overflow of the water. So, let’s see what causes water to leak from under the toilet?

1. A Leaky Water Line:

In most cases, water leaks in the shower base because of broken water lines. You will see that the hose connects the water supply valve and toilet tank. Due to years of use or overpressure, the supply line may get damaged.

As the toilet water supply hose leaks, the water will accumulate over the floor. Gradually, it will cause the toilet and shower to overflow.

2. Clogged Drain Line:

At times the drain line of your toilet and shower may have clogged. Thus, the water will fail to pass through the drain line. Water will stop passing through the drain line entirely when the toilet drain line gets fully clogged.

As a result, the water will back up from the toilet and accumulate on the floor. You will also experience a bad odor due to the overflow. It happens because the water coming from the drain isn’t hygienic.

3. Condensation:

In the rarest cases, condensation will cause water to overflow on the toilet floor and around its base. At times, the interior air is warmer than the exterior temperature. Then the water will accumulate over the toilet tank.

Due to the temperature imbalance, the accumulated water slowly condensates. After that, the water runs down to the lower surface of the toilet and causes an overflow. Thankfully, it is one of the rarest occasions you will ever find for water overflowing the toilet base.

4. A Damaged or Worn-Out Shutoff Valve

The shutoff valve allows you to control the water flow in your shower and toilet. However, it may get rust, corrosion, or other damages over a certain period. Also, the washer, O-ring, and other parts of the shutoff valve will wear out after 7 to 10 years of use.

When any of these parts get damaged, the shutoff valve becomes leaky. Usually, the seal of the shutoff valve gets damaged, which further causes leaks and overflow. Thus, you need to check the valve to see if it is responsible for the water overflow in the toilet.

5. Loose Flange and Flange Bolts:

The toilet flange holds the toilet on the floor. Similarly, the toilet flange bolts will hold the toilet bowl tightly against the flange. Sometimes either the toilet flange or its bolts may get loose. Since water runs through the floor in the bathroom, the bolts may get rust. Also, it may become corroded due to years of use without maintenance.

As the bolts become loose, the toilet flange will start leaking water around it. You may tighten the bolts with pliers set to stop the unwanted leakage.

6. Worn-Out Wax Ring:

The wax ring for the toilet is made of wax for its easy molding facility. You may use the wax ring to place it around the toilet bowl. So, it will secure the toilet bowl and stop water from overflowing. It stops the water from coming out around the toilet base.

Since it is made of wax, the ring may get damaged easily. Water will drip through the damaged parts when the wax ring gets damaged. Although it won’t flood the toilet floor, it will gradually cause an overflow. You will need to replace the wax ring when it happens.

7. Cracked Toilet Bowl:

In the worst-case scenario, the toilet bowl will become cracked. It will cause an overflow in the shower base. Of course, toilet bowls are built sturdily. Yet, it may get cracked accidentally. When it happens, you need to replace the entire toilet bowl.

Unfortunately, replacing the toilet bowl is costly. You must spend $500 to $1000 or even more to replace the cracked toilet bowl. It includes the cost of the toilet bowl and the plumbers’ expenses.

How to Fix a Toilet That Leaks At the Base?

A leaky toilet base is responsible for leaks in the shower and toilet floor. We’ve described the top reasons for it. So, let’s see how to fix the leakage.

Method 1: Fix the Damaged Water Line

If the leakage in the water line causes the toilet base to overflow, you need to fix it. You can fix the damage with plumbing putty or Teflon tape if the damage is smaller. You need to call a professional to fix the larger damages.

Usually, plumbers will apply aluminum or copper wrapping over the damaged water line. It fixes the leaks permanently.

Method 2: Change the Shutoff Valve:

You will need to replace the shutoff valve if it causes leaks. In most cases, you will have to replace the O-ring or washer to ensure a watertight seal of the shutoff valve. You need to hold a small bowl under the valve first. Then, flush the toilet.

If there’s a leak in the valve, water will drip through the damaged seal. Thus, you need to reseal the point. If the knob of the shutoff valve is damaged, you will need to replace the entire valve.

Method 3: Unclogging the Drain Line:

In many cases, the drain line will get clogged and cause water overflow in the toilet base. So, check the drain line. You can use a plunger or plumbing snake to remove the residual development from the drain line.

For this, turn off the water supply line. Pour boiling water through the toilet to the drain line repeatedly. It will weaken the residues, and you can remove them with the plunger. Also, you can use baking soda and vinegar mixture for a better result.

Method 4: Tightening and Replacing the Toilet Flange:

A damaged toilet flange and loose bolts often cause a leaky toilet base. Usually, two bolts hold the toilet bowl tightly with its flange. As the bolts wear out, the toilet bowl becomes loose. So, water will come through the loose points.

At the worst, the toilet flange will need replacement. Check the flange closely to see wearing-out signs. You will need to remove the toilet bowl by unbolting it. Also, take help from a second person to remove the bowl as it is heavy. Now you may pry off the toilet flange and install the new one.

Method 5: Replacing a Cracked Toilet Bowl or Wax Ring

You will need to replace a cracked toilet bowl if you are unlucky. The bowl is usually made of porcelain and lasts for 10 to 15 years with ease. Accidentally the porcelain bowl may get cracked, which will need replacement.

You must call a professional plumbing service to replace the toilet bowl. It is crucial because, without the proper installation, it can ruin the toilet floor. It will cost you even more dearly.

Similarly, you may need to replace the wax ring around the toilet base.

Frequently Asked Questions

Can a clogged toilet cause it to leak the base?

Answer: Yes, clogged water in the toilet will apply pressure on the wax ring. Consequently, the wax ring gets damaged, causing leaks around the toilet base.

How do you know if the toilet is leaking under the floor?

Answer: You will hear noise, dampness around the toilet floor, or a stained toilet base if the toilet leaks underneath the floor. You may easily identify the leaky toilet floor with these signs.


When showering, water leaking under the toilet base is the worst nightmare for homeowners. If the problem happens due to a clogged drain line or worn-out flange bolt, or wax ring, you can resolve it at a reasonable cost. However, you must pay heftily if the toilet base leaks due to a cracked bowl or damaged water line. It can cost you from a few hundred to a thousand dollars.

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