Here’s a nasty situation we hear from homeowners, “When I flush my toilet, the toilet water rises out of the shower drain.”

So their question is, “Why in the world would my toilet water back up into my shower drain?”

Read on to learn why your toilet may be backing up into the shower.

Common Causes of Your Toilet Backing Up into Your Shower

The main reason the toilet is backing up into the shower is likely because of a sewer line clog.

Basically, your toilet uses a sewer line to transport water waste from your home to the underground sewer main.

But because the sewer line is clogged, raw sewage can’t exit the home and backs up through other drains (in this case, the shower drain).

Thus, if the toilet backs up into the shower, you need a plumber to clear the sewer line clog as soon as possible.

Why so quickly? A sewer line clog presents a health hazard to your family and will eventually lead to a pricy sewer line repair or replacement.

Tree Roots

Another reason the toilet may back up into the shower is tree roots. Yes, tree roots can find their way into the sewer line because they grow toward available water sources. This means that any trees in your yard or surrounding properties can grow into your sewage system.

This situation is more likely to happen during drier seasons or if your system leaks.

Flushed Foreign Objects

Flushing man-made objects, even supposedly “flushable” products, can wreak havoc on your sewer line. This includes everything from wipes and feminine hygiene products to things you definitely shouldn’t flush, like towels and toys. Even flushing paper towels or large wads of toilet paper can cause blockages.

If an item makes its way into the plumbing system, causing an obstruction, the toilet and shower will become clogged at the same time.


It’s natural for your hair to shed as you shower or bathe. A couple of hair strands will drain perfectly fine through the plumbing system.

However, over time, the accumulation of hair will eventually form an obstruction and clog your drain. A drain clog from hair is inevitable if:

  • You have long hair
  • You lose a lot of hair when you shower
  • You use the shower to bathe your pets

The stuck hair will prevent fluids from draining as intended and can prevent drainage altogether. If this happens, flushed toilet water will likely come up in the shower.

Pipe Scale

Pipe scale is a mineral deposit (calcium and magnesium) that occurs naturally in unfiltered bath water, meaning it’s in your showers, sinks, and toilets. However, pipe scale can build up and clog your sewer line, leading to backups.

If your home has hard water, pipe scale clogs will be more frequent, as hard water has a high mineral content.

Grease, Oil, & Fats

Have you ever noticed what happens in the pan after cooking greasy food? As the liquid grease sits in the pan, it turns into a sticky, thick lard. This thick substance suddenly becomes a nuisance because it can easily clog the drain.

This is why experts recommend that you don’t put grease, oil, or other fats down your drain. Even washing these substances off dishes can damage your pipes.


These liquid substances congeal within the piping, causing blockages. In fact, these organic substances are one of the biggest culprits of blocked pipes in the plumbing system.

Other Objects

Often, there isn’t just one thing that causes problems with your sewer line; it’s a combination of different objects and products.

For instance, food waste, laundry detergent, and soap can work together to cause blockages, which can lead to toilet water backing up in the shower.

Your drains are like rivers with branches. Smaller pipes merge with one larger pipe to carry the waste away from the home. But if there is a blockage at one section, a backup could occur at any other branch, including those connected to the showers.

This is why you must call a plumbing professional to assist with clogged pipes. They can identify the clog source and appropriately alleviate the problem.

Main Line vs. Secondary Line Clogs

When a plumber comes by, they may mention that you have a clog in the “main sewer line” or a “secondary sewer line.

What does that mean?

Well, your home’s plumbing is like a tree:

Only a few drains will back up if the clog is in a secondary sewer line. In your case, the water from the toilet is backing up into the shower.

But if the clog is in the main line, you’ll have issues with every drain in your home, not just the toilet and shower drain.

Learn more: 3 Messy Signs That Your Main Sewer Line is Clogged

Can You Fix It Yourself?

Unfortunately, no. Clogs in the sewer line (especially the main line) can’t be fixed by a simple plunger or toilet auger.

You’ll need to call a professional plumber to find the location of the clog and clear it.

Typically, a professional plumber will approach the problem like this:

Best case scenario: The auger fixes everything, and you can go about your day.

Worst-case scenario: The sewer line camera finds a serious issue, like tree roots growing on the sewer line or the sewer line has collapsed and needs replacing.

Get Professional Drain & Plumbing Help in Atlanta

Contact us if your toilet is clogged and your shower is backed up. Ragsdale Heating, Air, Plumbing & Electrical provides expert drain cleaning and plumbing services to the Atlanta metro area.

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