Toilet Backing Up Into The Shower? (Here’s What To Do)

Toilet Backing Up Into Shower

If you’re suddenly facing smells and wastewater coming up through your shower drain, it’s anything but pleasant. These ill effects result from your toilet backing up into your shower, but how does it happen? And, more importantly, what can you do about it?

The reason a toilet backs up into the shower is an obstruction in the main sewer line. All of your different drain lines are connected, heading to the mainline to go outside your home. When the mainline has a clog or blockage, it sends wastewater in reverse, backing up into other fixtures.

Many different things can cause these obstructions, and you have a few options when it comes to a fix. You can try snaking the drains or checking for a blocked vent pipe. But, in many cases, you might find it in your best interest to call a plumber.

Why Is My Toilet Backing Up Into The Shower?

Your toilet and shower are connected since all of your home’s drain lines head to the same main sewer line. Typically, when everything is in working order, you flush your toilet, and all goes well. Wastewater runs down the toilet drain, through the drain line, and out of your house through the main sewer line.

However, when something blocks the mainline, it can cause issues in any and all of your other fixtures. This is because the wastewater hits the obstruction, and with no place to go, has to back up. (Think of it like a car reaching a dead end; you have to turn around).

The water and anything in it, like feces and urine (eww), reverse in the line, flowing into other drain lines. This backup results in water coming back up through your toilet, causing an overflow. But, it can just as easily make its way up through your shower drain.

So, this begs the question, then what’s causing the backup? Well, several things can clog your sewer main; and many of them are common things that clog toilets.

1. Flushing Foreign Objects

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In a nutshell, it’s best not to flush anything down your toilet except for human waste and toilet paper. Even if an item claims to be flushable, your better bet is to toss it in the trash. However, lots of foreign objects tend to end up in the sewer line, usually because someone flushed them.

For example, things like Q-tips, baby wipes, dental floss, and even the odd children’s toy or sock end up going down the drain. Some of these items are large enough to cause a blockage on their own, while others build up over time.

Dental floss, in particular, can catch and snag on other items and turn into a weird, clog monster.

2. Tree Roots

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Your sewer line might meet damage from various tree roots seeking water. As the roots move and spread through the ground, they head for the water in the pipes. These roots can eventually bust through your sewer line.

Broken and damaged sewer lines cause all sorts of problems, including nasty backups. Even crazier, it doesn’t even have to be a tree in your yard; it could be from a neighbor. Some persistent and thirsty trees might even head to your sewer line from several houses away.

3. Scale and Build-Up On Pipes

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Anything can build up over time, including soap and similar items that can turn into sludge in your pipes. Also, minerals naturally occurring in water, like magnesium and calcium, can form scale on your pipes. If this scale builds up enough, it can lead to a blockage.

4. Fats, Grease, And Oils

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Although not from your toilet per se, your shower could be backing up from grease and oil in the line. It can build up and form some gunky clogs, backing up into all of your drains, including the shower. So, sometimes, when you think it might be your toilet causing the backup, keep in mind, it could be something else.

5. Hair

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Hair can accumulate over time and form a massive hairball blockage, especially long hair. However, short hair can also be troublesome. If you have a habit of giving yourself a trim and flushing your snips down the toilet or drain, don’t.

6. Toilet Paper

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Yes, toilet paper is supposed to go down your toilet, but it can still cause issues. If you use a lot of paper at once, especially thicker paper, it can bunch up and form a clog. Try to limit the amount you use, fold it instead of bunching it up, and opt for 1-ply.

If you do use a lot of toilet paper at once, consider a courtesy flush. In other words, flush a second time to give the mass of paper an extra nudge down the drain and on its way.

How Can You Stop The Toilet From Backing Up Into The Shower?

Now that you know some of the most likely reasons for your unpleasant plumbing problem, it’s time to fix it. In some cases, you might be able to tackle the backup yourself, even if with just a temporary solution.

1. Turn Off The Main Water Supply

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While it won’t solve the backup issue, shutting off the water supply is critical to stop the backup from getting worse. Before you end up with a flooded bathroom, turn off your main water supply.

You’ll typically find your main water supply in the basement or near your water heater. It could also be in your garage or along the exterior of your house.

It’s a good idea to familiarize yourself with its location in case of an emergency. Also, shutting it off if you’ll be away from home for a lengthy period can thwart any unexpected floods.

2. Remove The Cleanout Line Cap

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In addition to shutting off the main water source, it’s advisable to remove the cap from your cleanout line. You’ll typically find the cleanout pipes near your house or on the lawn; it’s short, round, and white.

Removing the cap helps release built-up pressure in the line, which can keep water from flowing back to your home. Again, while these two steps aren’t fixes for the actual blockage, they are crucial for avoiding further problems or damage.

3. Use A Plumbing Snake

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If you suspect a blockage from something like a child’s toy or giant hairball, you can attempt to snake the line. However, it might be a long shot since the blockage is likely further down the sewer main.

Try snaking the toilet first by feeding the snake down the toilet drain. Be careful not to scratch up the porcelain. Move the snake around and up and down and then retract it using the crank.

If the snake isn’t reaching, you can attempt to snake the shower drain. You need to remove the drain cover; use a screwdriver to simply remove the screws.

Then feed the snake down the shower drain, spinning it as you go. Spin it in the opposite direction as you pull it back out, hopefully removing the clog with it.

4. Run High-Pressure Water Through The Line

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Attach a high-pressure nozzle to your garden hose (do not use a pressure washer). Place a bucket near the cleanout line to catch any water that might come back out the line.

Remove the cap from the cleanout line and feed the hose into the line as far as you can. Hopefully, you can get it close to the clog.

Then, turn on the water slowly and move the hose back and forth to try and blast through the clog. Gradually increase the pressure by opening the water valve more. If you think you made it through, keep the water running for a few minutes to ensure the line is clear.

5. Check The Vent Pipe

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The pipe on your roof that vents from your bathroom to outside might be the culprit. Over time, vents can get blocked by twigs, leaves, and other debris. If you see anything, remove it by hand or with a tool.

If you suspect the vent has a blockage further down, you can use a snake to push it out. Alternatively, you can try spraying it out with water from the hose.

6. Call A Plumber

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While these fixes can help, in many cases, if you’re facing a significant backup, it’s best to call in a plumber. A professional can likely handle the issue in record time and ensure no further damage occurs. They can run a camera through your line to quickly identify the cause of the blockage.

Frequently Asked Questions

Can I use Drano or chemicals to clear my sewer main or a clog?

As tempting as it is to reach for a product to solve your problems, this one is best left undone. Many professional plumbers advise against pouring Drano and other chemicals down your drains and toilet. Not only can certain chemicals damage pipes, but they can potentially make clogs worse.

Can bleach clear a toilet clog?

Similar to using other clog-busting chemicals, bleach is best left out of your toilet. While bleach can break down a soft clog, like gunk buildup, it’s not recommended.

Bleach creates strong fumes that can cause irritation to your eyes, throat, skin, nose and trigger other issues. If you use it along with other chemicals, you could produce toxic fumes.

So, it’s best to forget about the bleach, but if you’re determined to try it, protect yourself. Wear gloves, goggles, and a mask, and don’t use any other chemicals before or after. Pour about three cups of bleach into the toilet bowl, leave it for about 10 minutes, then flush.

Why does flushing my toilet make my shower run hot?

It’s not a secret that your toilet and shower systems connect. Therefore, it should be no surprise to get a blast of hot water during your shower if someone flushes. But, why is the water hot?

It comes down to your plumbing system, which is likely a trunk and branch system. Put simply, it’s one trunk that feeds many different branches, going to other places. But, if one fixture is using water and another fixture needs it, it will pull the water from elsewhere.

So, when you’re showering and have your water at the perfect temp when someone flushes, the toilet needs to refill. The toilet needs cold water to fill the tank, and it has to get it from somewhere–your shower. Suddenly your shower has less cold water, leaving you with more hot water than you want.

Toilet Backing Up Into Shower
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