Why Does my Toilet Bubble When Showering?

Bubbling or gurgling toilets may be a common issue, but it is not normal. Ignore the problem long enough and your toilet might eventually start overflowing.


Why Does my Toilet Bubble When Showering?

If you notice air bubbles in the toilet while you shower, this may be an indication of an underlying plumbing issue. Toilets tend to make bubbling or gurgling sounds when the water from your shower doesn’t drain fast enough and begins to fill up the pipes. It can be an indication of a clogged drain or vent stack.   

Now, some people may not be as bothered by these noises as others. That is not a good enough reason to ignore the issue altogether. As we mentioned earlier, that gargling sound is a sound of trouble.

You need to take action before the problem gets bigger.

So, let’s take a look at the…

Table of Contents

Phenomenon that is known to cause that bubbling gurgling sound…

Wet Venting

Plumbing has been around for ages. The World’s oldest drainage system dates back to about the 6th century BC, and many believe that it can still function the way it is supposed to.

So, plumbing has come a long way over the centuries, and so have certain rules by which you should abide. One such rule is to vent every drain separately. The purpose of these vents is to prevent pressure build. These vents not only disperse sewer gases outside the house, but they also prevent the formation of a vacuum.

Practically speaking, not all bathrooms are large enough to allow proper vents for all drains. So, when all the fixtures are too close to each other, a single vent is used for multiple fixtures. Your sink, toilet, and shower may all be using a single vent and a single drain. That is called wet venting.

The reason plumbing rules are all so frequently forfeited in favor of wet venting is that this configuration is quite practical for small bathrooms. It works just fine – at least until the pipes are clogged.

How Does a Clog Cause Bubbles?

Let’s take a look at these diagrams to understand how wet venting looks like and how a clog can impact it.

Here you can see a basic representation of plumbing in a wet vented bathroom.

A clog may form anywhere in the system. When you shower, this clog will restrict the flow of water.

Eventually, the pipes begin to fill up because the drainage is slower than the flow of water in the pipes. The water cannot flow out of the drain as quickly as it flows in the pipes.  

The increasing water pressure will force the trapped air in the line to find an outlet. At this point, the toilet will serve as that outlet and hence, the bubbles and the gurgles.

If you keep showering till the pipe is filled, your shower drain will start to back up and, eventually, the toilet.

This is precisely why it is not a problem to take too lightly. Those bubbles won’t remain harmless for too long. If you also notice that your bathtub or shower drain too slow or the toilet fills up a bit before it flushes out, this is also a sign of clogging.

Here is another useful video:

Now, let see what you can do to fix this problem.

How to Fix Bubbling Toilets

We strictly don’t advise DIY when it comes to plumbing unless you have the necessary training and experience.

Now that you know pluming is sort of an ancient art now merged with modern science, there is a vast pool of knowledge you need before you even attempt to fix anything. That is why professional help should be a priority.

However, if you insist on DIYs because you do have the skills and tools, here is what experts recommend.

The Simple Fixes

This one is a DIY we won’t warn against, but it only works when the clog isn’t too stubborn. A simple plunger can push a small clog out. However, it is important to seal shut the drains of other fixtures you plunge. Otherwise, the pressure will push the water out of those drains instead of dislodging the clog.

Duct tape can do a decent job of shutting your sink and shower drains.

If the plunger doesn’t work, the next easy solution is a sewer snake or an auger. An auger will work best when to clog isn’t too stubborn but a little further down the pipe. Most augers tend to around 5 to 15 feet long. Usually, it is easy to tell if the auger has hit the clog and is effectively removing it.

Chemical Cleaners

For stubborn clogs, there are chemicals that can be used. However, these chemicals are too harsh, and excessive usage may damage the pipes. So, it isn’t something you should use too often or even something you should do on your own.

The chemicals are unsafe for humans and proper precautions are need to prevent a mishap. Most of us won’t even know the right quantity to use. Besides, the drain cleaners available in the market may not work on old and stubborn clogs. You can, however, use these chemicals along the sewer snake to see if they can fix the problem as a team.

The Ultimate Solution

If all the above fixes prove futile and the clog is too stubborn to budge with a plunger or snake, even with chemicals, you need to call a licensed plumber. Professionals will analyze the entire situation and might come in with a motorized auger to the rescue.

Motorized augers can stretch as long as 100ft and are powerful enough for stubborn clogs. However, you are required to remove the toilet before you can use this bionic snake to clear the drain.

A motorized auger may seem like a simple machine to operate, but it requires professional expertise. Use it wrong, and you can damage your pipes, leaving a bigger mess than you started with. So, even if you are tempted to use it on your own, we don’t recommend it.

Other Possible Reasons

Here it is worth noting that the clog may not always be in the drain. Sometimes the clog or blockage can be in the vent stack located outside the house. These vent stacks can clog up due to leaves, feathers, and debris outside the home. Sometimes these vents can be blocked by a dead animal’s carcass.

If you can easily remove that blockage by hand, which might solve the issue. If you can’t see anything blocking the vent, use a garden hose to put some water down the vent, this will give you an idea of how far inside the vent that blockage may be. An auger can be just as effective for cleaning the vent stack.


To conclude, all we can say is: bubbles in the toilet are never good news. If they form when you are using the shower or even the sink, it is an indicator of a clogged drain or a blocked vent. Without proper tools or prior experience, it is best to call a licensed professional.

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