Why Does My Toilet Bubble When the Bathtub Drains? (3 Causes)

Written by

Paulk Webb


Freddie J. Hagopian

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why does my toilet bubble when the bathtub drains

Have you ever finished taking a long and relaxing bath and then freaked out five minutes later because of gurgling noises and uninvited bubbles coming out from your toilet?

You’re not the first person to ask, ‘why does my toilet bubble when the bathtub drains?’. The answer is quite simple – there may be some blockage happening on your vent pipe or drain pipe.

Read along if you want to deeper (see what we did there?), understand the causes of bubbles coming out of the shower drain, and how you can fix it.

Reasons Why My Toilet Bubble When the Bathtub Drains

The reason why your toilet bubbles when tub drains may not be as terrifying as creatures hiding in the sewers, but this does not mean you don’t need to take seeing bubbles in the toilet bowl any less seriously.

1. There’s a block in your drainpipe


What causes these bubbles are clogs which can result in either a partial or a complete blockage on your draining system.

When clogging occurs, once you drain a massive amount of water as you use in your bathtub, instead of the water and intense air pressure going smoothly towards your shower drain septic, it gets blocked along the way which causes the air to rise to your toilet. It then creates those bubbles and gurgling sounds in your toilet.

When you have hair, dirt, or soap clogging your main vent pipe, you can expect to hear toilet gurgles after a bath or even a shower.

2. Your vent stack is clogged


Another reason for seeing bubbles in your toilet bowl is a clogged vent stack. A vent stack is a ventilation system some buildings may have installed. It’s also connected to the drainpipe, but its primary purpose is to facilitate proper air ventilation.

Ven stacks are often installed on the roof, and a blockage in your vent stack can cause the sewer gases to flow toward your toilet and sink rather than outside the house.

3. Wrong Plumbing


A serious reason that will result in more problems besides a bubbling toilet is the incorrect installation of pipes. When your pipes are installed at the wrong angle or slope, water may accumulate rather than go down correctly, resulting in blockage.

It may not sound pretty, but your bathtub and toilet are connected. That’s why you might hear the toilet gurgles even when the toilet clogs in the bathtub.

There’s no need to feel dirty! Your toilet and bathtub still have their own drain pipe, but they may attach to a single pipe as they go down the shower run septic or sewage, depending on where you live.

This plumbing structure is common to small bathrooms where multiple fixtures are installed closely, so toilet bubbling, and other problems with toilet drains are likely to happen if the plumbing is not done right.

How Do You Fix a Gurgling Toilet?


The simplest way to fix a gurgling toilet is to get rid of the blockage, whether it’s in your drain pipe or vent stack. There are safe and simple items you can do to clear the clogs, depending on the size, location, and type of material that blocks them.

1. Plunge or snake your toilet or bathtub

You can use a plunger or a toilet snake for minor clogs. It can effectively push the clogs and clear your drain pipes in a matter of seconds. And, they work most of the time, especially if your plumbing is sound.

2. Unclog your vent stack

When it comes to your vent stack, outdoor elements are the usual suspects as to why your toilet bubbles when the sink drains or when the shower drains.

If you have a ladder, try to check the vent stack from your roof and remove any leaves or materials accumulated there. This will instantly help your vent stack to circulate air in your drainage system effectively.

These are practical steps in fixing your clogged drain pipes or vent stacks if you want to stop hearing your toilet gurgle when the shower runs. Still, they are only applicable with minor clogs.

If you find that these do not work, getting help from plumbing professionals is always the best decision you can make.

How to Prevent Air Bubbles in Toilet


Here are a few tips for preventing air bubbles in your toilet:

  • Always use a shower drain to collect hair, soap, and other materials. This will ensure that only water will go down the drain.
  • Be mindful of the things you flush. Your toilet is dedicated only to human waste (and toilet paper) so refrain from flushing down other things.
  • Use a mesh screen for your bathtub.
  • Check and clean your vent stacks You don’t need to disassemble anything necessarily, but clearing out materials on top of your vent stack will prolong its life and prevent clogging.

Why Call a Professional to Fix the Situation?


How we wish that a gurgling toilet fixes itself! However, we need professional plumbers to rescue us most of the time.

It’s always a good idea to do plumbing with others. You may be eager to use strong chemicals to dissolve the clog in your drain pipes, but these can irritate your skin and eyes and even burn your throat.

Professional plumbers have years of training and experience to resolve your gurgling toilet.

They have all the equipment to do the job that you can’t just purchase from your local hardware, and you don’t need to compromise anyone’s safety.

Hiring professional plumbers saves you a ton of money. Imagine digging deep into your own pipes and ruining your bathroom without knowing where the exact clog is.

Plumbers receive hundreds of ‘my toilet makes this sound when I flush it’ and ‘I think I just broke my bathtub’ calls daily, and they always know what to do.

Why My Toilet Won’t Flush When I Take a Shower?

The clogs in the joined drainpipe of your bathroom and toilet might be the reason why when your shower runs, the toilet cannot flush and make a gurgling sound.


Since you know that the answer to ‘why does my toilet bubble when the bathtub drains?’ is a blockage on your drain pipes or vent stacks, you can now try to do the safe quick-fix we mentioned above.

If you want a stress-free way to stop your gurgling toilet and take as many baths as you wish without worries, call a professional plumber and watch those bubbles disappear in no time. Also, be sure to prevent any other toilet worries by doing our tips above!

Read more: Why is the toilet bubbling and gurgling when the washer drain.

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