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Why is my toilet backing up into my shower and how do I stop it?



If your toilet backs up into your shower or bathtub, it can be a bleak reminder that the two systems are connected. If several kitchen and bathroom sinks, showers, toilets and other drains to the sewage system are backing up, then you might have a blockage in your main sewer line.

If it is only wastewater gurgling up in one location, such as your shower, the clog may be closer to your bathroom and could possibly be fixed by someone with even modest DIY skills. Here are some of the things you can try if you find your toilet backing up into the shower. 


What’s causing the toilet to back up into the tub or shower drain?

There are many reasons that a blockage in a main line can cause your toilet to back up into your tub or shower. Let’s review some of the most common reasons for this issue. 

Flushed foreign objects

Oh, the list of things that have been tossed into toilets, flushed and caused major backups is long and uncanny. Ask any plumber and they will recite you an impossibly long catalog: kids’ toys, feminine hygiene products, unwanted meals, paper towels, shoes (don’t ask), flushable wipes (which aren’t really), and the list goes on and on.

Toilet plumbing and sewage systems are more delicate than you think. Human waste and biodegradable toilet paper are the only things that should go down them. Anything else can cause major backups into things like your shower drain, which could make you think twice about hopping in to clean yourself up. 

Tree roots

Tree roots need to drink water, and your sewer pipes are a plentiful source of H2O. If you live on a property with many older trees, you might experience roots breaking through your sewer system lines and causing clogs, especially if the pipes are older and have developed weak spots and leaks.

Other than cutting down the trees, there’s not a lot you can do to prevent this. And keep in mind the tree might not even be yours; it could be a neighbor’s with particularly thirsty and far-ranging roots.

When planting trees on your lawn, try to keep them far away from the sewer lines. Or if they have to be close or directly above the lines, try to choose trees with slow-growing root systems. A plumbing professional can verify if your line is clogged with a tree root by using a special video camera. They might remove the roots mechanically or chemically, and perhaps effect a trenchless sewer repair.


Unless you have underlying reasons, you probably only lose a bit of your hair while taking a shower or bath. The trouble is, the hair can build up over time to block your drains and potentially cause backups into your bathtub or shower.

You can possibly prevent this by:

  • Brushing or combing your hair before you bathe, removing loose strands.
  • Installing one of the different hair catchers on the market today. They let water run through freely but catch hair, so you can empty it into the trash rather than down the drain.
  • Pouring boiling water down the drain once a month, clearing small problems before they become major.
  • Taking care of blockages right away. If you get a small clog, take care of it immediately, perhaps using a bent wire or your hands to dislodge it, or pouring a mixture of baking soda and vinegar down the drain, followed by boiling water later.

Grease, oil or fat

Pouring cooking oil, fat or grease down your kitchen or toilet drains is definitely a no-no. The liquid fat hardens when it dries, sticking to your pipes and eventually causing obstructions that cause shower misery. Even greasy debris rinsed off dirty dishes can cause blockages.

The best way to stop this is to never pour grease, oil or fat down your sink or toilet. Another preventive measure is to pour boiling water down the drain once a month (see above). This can also help with soap clogs.

You should also scrape plates, pots and pans more thoroughly into the garbage before rinsing them in the sink. If you have a lot of oil or grease (for example, deep-fried fish), then dispose of the liquid in an old coffee can, seal it, and put it in your garbage, if allowed. Or you can mix it with old coffee grounds and dispose of it in small amounts in a compost pile.

Pipe scale

Scale is a mineral — such as calcium or magnesium — found naturally in water that can build up in pipes. After it builds up enough, it can cause troublesome blockages.

To prevent pipe scale buildup, use a commercial descaling product or pour a baking soda and vinegar mixture down the drain. You can also install a water softener, which will also supply soft water for drinking, washing your clothes, cleaning dishes and taking showers. The water softener slows down mineral buildup substantially, but you will still need to descale drainpipes periodically.


4 fixes to stop your toilet from backing up into the shower

Some blockages you can remedy yourself — it just takes a bit of know-how and some elbow grease. For more serious clogs, you might want to call a professional plumber.

Use a plunger for smaller clogs

For a smaller clog found not too far down the drain, try a plunger first. It’s good to have one with an extension flange that provides a better fit on the drain and gives you greater suction. Wear eye protection, an old shirt and gloves in case anything splashes back. 

Extend the rubber flange, position the bell-shaped end of the plunger over the bottom of the toilet bowl, and ensure there’s enough water to cover the rubber end of the tool. Do one gentle push, releasing all the air from the plunger, and then plunge harder for 15 to 20 strokes. Flush the toilet to see if it drains properly. If not, plunge again. 

Use a drain snake for bigger clogs

You can use a drain snake or toilet auger for bigger clogs farther down the drain. A drain snake comes with a long cable, which has a blade, a corkscrew or a hook at one end — you insert this end into the toilet to cut through or dislodge clogs. Watch that the sharp end doesn’t cut the toilet finish (or you).

Once the cable is in the toilet, use the handle to crank it down the drain until you meet and remove the clog. Reel the line back in and flush the toilet to make sure everything works correctly.

Try at-home remedies

Besides commercial drain cleaners, some at-home remedies to unclog pipes include:

  • Mix a couple of teaspoons of dish detergent with 8 cups of boiling water and pour the mixture slowly down the drain. This sometimes works well with blockages caused by organic matter, grease, oil and fat. It works less well with hair. Don’t use this on PVC pipes or porcelain sink bowls.
  • A wire coat hanger straightened out with the hook left at the end can be used to snag some clogs.
  • Pour 1/2 cup of baking soda followed by 1/2 cup of vinegar down the drain, plug the drain, and let the mixture sit for 30 minutes to overnight. Then unplug the drain and pour hot water down it until clear.

Call a plumber

If the DIY remedies don’t work to remove blockages, it is time to call in a professional plumber. Perhaps it’s a deep clog in the main sewer line you can’t reach, or something so firmly lodged that it won’t move with amateur methods.

The plumber will have more tools, training and experience, which will save you from wasting your time and making costly mistakes.


Cinch home warranties cover toilets and plumbing systems

One strong, proven way to keep costs down due to problems such as clogged sewer lines is to get a Cinch Home Services warranty plan. For your peace of mind, and at a reasonable cost, the home protection plan can cover major built-in systems, such as plumbing, water heaters, toilets, furnaces, electrical and more.

After choosing the annual plan you wish, request service provided by the Cinch national network of vetted service technicians anytime you need it.

Your problems will be addressed professionally and efficiently, backed by a 180-day workmanship guarantee. You definitely won’t be flushing money down the drain. Reach out for an instant quote today.


Here’s how blockages in the sewer line can cause your toilet to back up into your shower, and how to prevent this issue.