Why is My Toilet Backing Up into Bathtub? [7 Ways to Fix it]

A bathroom is a place where we often have to be our most private and personal selves. So when something goes wrong with our plumbing, it can be a cause for great anxiety.

We may not know who to call, or what to do. And worst of all, we may not want anyone else to see the disaster that has unfolded in our bathroom.

toilet backing up into bathtub

But don’t worry – you’re not alone!

Plumbing emergencies happen to everyone at some point or another. And more often than not, the problem can be fixed without too much trouble.

In this article, we’ll explain what you should do if your toilet starts backing up into the bathtub. Read on for tips and tricks that will help you take care of the problem yourself – and save you from having to call a professional and break a bank!

Why My Toilet is Backing up into the Bathtub?

Your toilet will only back up into the bathtub if the sewer line is blocked. The sewer line can get blocked due to several reasons, which include the following:

1. Flushing foreign objects

Feces, urine, water, and biodegradable toilet paper are the only waste that should be flushed down the toilet.

However, some toilet users tend to flush paper towels, thick toilet paper, and/or flushable wipes after use. All of these are foreign objects to the toilet and can end up clogging the sewer line.

Foreign objects also include toys, baby wipes, menstrual pads, and other female products. Flushing any of these things down the toilet may clog the sewer line. This will subsequently cause your toilet to back up into the bathtub.

N/B: Flushable wipes are indeed flushable and won’t clog the toilet bowl. However, they are not biodegradable and may clog the sewer line.

2. Tree roots

Another possible cause of clogs in the sewer line is tree roots. Naturally, tree roots can penetrate deep into the soil seeking water, and the sewer line contains enough nutrient-rich moisture.

The tree roots can end up finding their way to your sewer line, especially if there are leaks in the line.

The tree root may eventually break into your sewer line and subsequently, stop drainage completely.

However, if you or your neighbor doesn’t have a significant sized tree, then you can rule out this issue. It only happens with massive trees.

3. Accumulation of hair strands

Here is a subtle culprit that usually goes unnoticed until the problem is done. Whenever we take our bath or shower, strands of hair inevitably fall out but we don’t always notice it. With time, these strands of hair can accumulate and form a mesh in the sewer line.

The mesh can then trap other materials in the sewer line that would have drained properly, causing a clog.

To avoid this kind of issue, you can simply keep the toilet bowl covered when not in use. Plus, don’t put hairs into the toilet. Use the garbage bin to dispose of hair and other fiber materials.

4. Grease, fats, and oil

Many people tend to overlook this and don’t consider it a problem. Most people usually wash fats, oil, hair wax, and grease down the drain. This may not look harmful at first as these substances are in liquid form when washed down.

Unfortunately, these substances will harden up in the sewer line when cool and stick to the sewer line. With time, they can build up in the sewer line and form a clog in the line.

If you have to dispose of these through the sewer line, you can use a degreasing toilet cleaner occasionally to prevent the accumulation of these things in the plumbing pipes.

5. Soil-shifting

This is a natural phenomenon and we can’t always prevent it from happening. Naturally, the soil shifts due to several factors, which include earthquake, rain, and flood. When this happens, it places undue pressure on the sewer line.

The sewer line can end up cracking, leaking, and/or collapsing in. The subsequent result is that soil will get into the pipe and clog it.

While this is a rare culprit for a backing-up bathtub, it is still worth mentioning in case you’ve ruled out everything and the problem is still there.

6. Natural Deterioration

Depending on the material the sewer line is made of, the sewer line may deteriorate over time. For instance, some sewer lines are made of cast iron pipes. Though very strong, cast iron pipes will rust and deteriorate over time.

More so, cast iron pipes are affected by some drain cleaners, especially those containing sulfuric acid.

Plastic pipes can become weak over time and crack or break.

Terracotta pipes are made of clay and tend to seep water and/or attract tree roots.

So, whichever material you use for the pipes, they can fail at some point.

7. Insufficient/blocked vent

Sometimes, slow drainage and even clogging may occur due to insufficient venting from the vent pipe. The main function of the vent pipe is to let air into the sewer line so that water can flow out freely.

If the vent is blocked or insufficient, it will result in a partial vacuum in the sewer line, which creates a slow drainage problem. Additionally, if the vent is completely blocked, it will result in a complete stoppage.

8. Other miscellaneous materials

Sometimes, the cause of the sewer clogging may be a combination of several different objects and/or substances. These objects/substances include rodents, food waste, dirt, soap particles, jewelry, rocks, and so on.

The problem with a combination of objects is that it can be hard to determine what the primary cause is. In this case, you may need to call in a professional plumber for help.

9. Old and outdated plumbing system

This is one of the most common causes of sewer line clogging. Over time, your plumbing system will become outdated and will no longer work as efficiently as it used to. This is especially true if your plumbing system is more than 50 years old.

An outdated plumbing system may have pipes that are too small or made of materials that are no longer durable. As a result, the sewer line may get clogged easily.

How to Fix a Toilet that is Backing Up into Bathtub?

Now that you know the reasons why a toilet can back up into the bathtub, here are the best solutions to fix the issue.

1. Use dishwashing soap and hot water

This method is very effective for clogs due to grease, fats, wax, and cooking oil. Boil about two liters of water in a pot until it gets hot.

Add about four to five tablespoons of dishwasher soap to the hot water. Mix the solution properly and pour the mixture down the drain slowly.

The hot water should melt the clogs away. Try this about three times and flush the toilet. If grease, fats, oil, or wax is the culprit, it should be fixed now. This method also works for clogs due to hair.

N/B: Be careful when using this method on porcelain sinks or PVC pipes. Don’t use boiling water to do the task. Warm water that’s not comfortable for the hand to submerge but won’t melt piping is what you would want to pour.

2. Use baking soda, salt, and white vinegar

Thoroughly mix 1/2 cup of baking soda with 1/2 cup of salt in a jar.

Pour the mixture down the drain. Also, pour 1/2 cup of white vinegar down the drain and plug the drain.

Let it rest for about an hour before pouring hot water down the drain.

For effective performance, allow the mixture in the drain overnight before pouring hot water down the drain.

You may use lemon juice as well if you can’t get white vinegar.

3. Use a bell-shaped plunger

If none of the solutions above work, that means the clog is more challenging and needs a more challenging solution.

Note that this method is only effective for removing clogs near the drain surface. If the clog is further from the drain surface, this method may not be effective.

Close the bathtub drain with any suitable seal and press down the seal firmly. You can use either duct tape or a flat-cup plunger. Closing the bathtub drain will cause more pressure to be directed toward the obstruction.

Flush your toilet as this will create more pressure in the drain. Start plunging immediately and aggressively several times using a bell-shaped plunger. Make sure that the water in the bowl is above the plunger cup for an effective result.

Flush your toilet to check if the situation has improved. If no improvement, plunge again.

Don’t forget to check the seal on the bathtub drain if it’s still intact. If not, stick it back and fortify it.

4. Use a toilet auger

If the method above seems ineffective, replace the bell-shaped plunger with a toilet auger (sewer snake) – don’t forget our gloves.

A toilet auger is longer – about three to six feet long – and can push through your toilet drain. Insert the auger gently into the toilet bowl and spin clockwise through the drain until you meet resistance.

Once you encounter resistance, crank the toilet auger to penetrate the clog. Then turn the auger anticlockwise to pull the clog out. repeat the process until all clogs are out.

5. Clear the vent opening on the roof

If an insufficient/blocked vent is the reason why your toilet is backing up into the bathtub, you need to clear the vent.

Use an auger to clear away any clog in the vent openings. Then use a garden hose to spray water into the vent openings.

6. Use hydro-jetting

Only a professional plumber can help you apply this solution. Hydro-Jetting shoots about 4,000 PSI of water through the sewer line to clear away any clog.

This method is very effective on almost all causes of clogs, including soil and tree roots clogging. Hydro-jetting will also clean the sewer lines and make it easier for water to flow.

7. Replace the sewer line

If none of the methods above work, it’s possible that the sewer line is extremely damaged/disintegrated and needs a replacement.

Replacement can be done using the traditional trenching method, pipe lining, and pipe bursting.

A professional plumber can help you determine the best option for your situation.

To Conclude

That’s all the seven methods you can try to unclog a toilet that backs up into the bathtub.

For effective performance, we recommend you to start with the easier methods (like using hot water or a plunger) before moving to more challenging ones (like hydro-jetting).

If none of the methods above work, don’t hesitate to call a professional plumber for help.

Sometimes, you won’t have any other choice other than to call for professional help.

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