Water Leaking Under Toilet Base When Showering: The Expert’s Solution (2024)

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.

Conclusion

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.

Water Leaking Under Toilet Base When Showering: The Expert’s Solution (1)

Paul Newman

Paul Newman is a blogger who writes about plumbing and home improvement. Over the past 20 years, I have worked as a plumber. My passion is to share my knowledge and experience with others to improve their homes.

Water Leaking Under Toilet Base When Showering: The Expert’s Solution (2024)

FAQs

Why is my toilet base leaking when I shower? ›

If you notice your toilet overflowing or leaking during a shower this is a sign of a clog. Usually this means there is a clog between the toilet and the sewer. The reason this becomes known during a shower is due to a backup of waste water lines in your home.

Why is water seeping out from under my toilet? ›

The only-when-flushed toilet leak could be caused by loose mounting bolts or a worn-out wax gasket while the all-the-time leak could be caused by a loose water supply line connection, a problematic water shutoff valve, or a faulty seal between the toilet tank and its base.

What may be the issue if the water leaks from the toilet base? ›

When a toilet leaks at the base, with water pooling on your bathroom floor, it's typically due to the failure of the wax gasket that seals the toilet to the floor. This seal should make a watertight connection between the toilet and floor. A leak often means that the wax seal may need to be replaced.

What is the best sealant for a toilet base? ›

It is recommended that you use a silicone base caulk due to its waterproofing capabilities.

How do you seal a leaking toilet base? ›

Why is water leaking from under my toilet? As was already said, it's most likely the wax seal leaking. Generally, that is a fairly simple fix - unbolt the toilet from the floor, scrape the old wax off the toilet and the flange on the floor, replace the wax and bolt down the toilet.

What does seeping at the base of your toilet mean? ›

The most likely culprits are the drain line, wax ring, flange bolts, cracks, or water supply line. You can replace a wax ring on a toilet, or you can call in a pro for the job.

Why is my water leaking from the bottom? ›

One of the most common reasons for a water heater to leak from the bottom is a faulty or damaged Temperature & Pressure (T&P) valve. The T&P valve is a safety feature that helps to release excess pressure and temperature from the water heater.

Should you caulk around a toilet? ›

Caulk keeps your toilet secure the floor, and avoids any chance of injury or toilet malfunctioning. It's actually required by the International Plumbing Code to caulk a toilet to the floor, and now knowing the reasoning behind it, why would you not want to?

How much does it cost to fix a leak at the base of a toilet? ›

It costs between $150 and $300 to fix a leaking toilet in most cases. The cost would be a lot more if the leak has caused damage to your floor or if it's a recurring problem.

Is toilet leaking at bottom an emergency? ›

Suppose you have a toilet leaking from the base. In that case, it's definitely an emergency—that water is seeping into your floor and subfloor, where it can cause serious water damage issues such as wood rot and eventually lead to structural stability that must be addressed for your household's safety.

How to tell if a toilet wax ring is leaking? ›

Here are the five most common toilet flange and wax ring leak symptoms:
  1. Your toilet is wobbly. ...
  2. Odors. ...
  3. Water puddling where your toilet meets the floor. ...
  4. The floor around the toilet feels springy or spongy. ...
  5. The flooring around your toilet is coming up.

Can you use Flex seal on a toilet base? ›

Bathrooms. Flex Glue can be used for an assortment of bathroom repairs. Customers often use the waterproof glue to fix toilet tanks, shower tiles, sink pipes, and other bathroom needs. Flex Glue is also mold and mildew resistant, making it perfect for bathroom repairs.

Can I caulk a leaking toilet base? ›

Using caulk to surround the base of the toilet should not be considered a leak barrier, but rather a way to help secure the toilet to the floor. If you have worked to position the toilet properly and secured the tee bolts, caulking the base solidifies your work.

How do I stop water from coming out of the bottom of my shower? ›

If the O-ring looks decent, use a cloth to clean any debris around it. You can also apply a thin layer of plumber's grease around the O-ring to help create a watertight seal. If the shower is still leaking, there may be a problem with the valve, and it will likely need to be replaced.

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