Bathtub Drain Gurgles when Toilet is Flushed: Noise Removal Guide

A co-worker of mine recently approached me complaining about a noise problem in her bathroom. Apparently, her bathtub drain makes a very annoying gurgling noise every time she flushes the toilet.

My co-worker came to the right person, but as knowledgeable as I am when it comes to fixing noise problems similar to this one, I wasn’t so sure what the cause of this problem might be and how she can fix it.

I had never come across this exact type of problem before. To my surprise, once I’d done some research, I realized the problems and solutions are similar to when your sink gurgles.

I wanted to share this knowledge with you and help you overcome this problem easily and without too much unnecessary work or money-spending.

bathtub drain gurgles when toilet is flushed

Why is your bathtub drain gurgling?

There can be a couple of causes for the gurgling noise your bathtub drain makes when you flush the toilet.

We can all agree that the gurgling sound is quite annoying and inconvenient, especially at night when you have to use the toilet without disturbing the sleep of your housemates.

The main reason for this is the air coming in and out of the vents. There are two possibilities here.

1. Air coming in

One of the most common causes of the gurgling noise is the air that comes into the vents. This can happen if your vents get clogged or blocked by something.

If they get clogged there will be pressure differences and this is not a good thing when it comes to vents. Due to the differences in pressure, the air has to go out through the fixture traps. This is when the gurgling noise happens.

2. Air coming out 

Another possibility is that the cause of your gurgling problem is the air coming out of the vents.

If your pipes are too clogged due to a lot of waste that travels through them, differences in pressure might start to create problems for you.

The pressure in the pipe in the area in front of the most clogged part of the pipe will become too high and this will force air to come out through fixture traps.

bathtub-drain-making-gurgling-noise

What to do if Your Bathtub Drain Gurgles when Toilet is Flushed

There is a large number of solutions for your problem and I chose some of the most effective and practical ones.

Of course, the solutions largely depend on the exact cause of your problem and your skillfulness when it comes to plumbing work.

If you're not very familiar with plumbing, you might want to call a professional to help you in some of these situations.

Luckily, in most cases, you'll be able to get rid of this noise all by yourself and very quickly.

1. Clearing the vents

Getting rid of the noise when the cause of the problem is the air coming into the vents is easier than you may think.

All you need to do is clear your vents, which is also recommendable even if you don’t have this kind of a problem. There is also a possibility of adding some additional vents, which is as effective as the clearing.

2. Increasing the pipe diameter 

This problem might appear if you use too much toilet paper at once or flush things that are not appropriate for the pipes down the toilet.

Of course, you should pay attention not to do any of these things, but what if the problem still remains even if you do pay attention?

Well, another solution is to increase the diameter of the pipe, which is not too expensive and can be a completely permanent solution to this kind of a problem.

3. Plunging your toilet

One of the easiest ways to get rid of the gurgling noise is through plunging your toilet. Doing this is fairly easy.

First of all, you need to cover your bathtub drain with something. You’ll need a plunger, which you probably already own. Now, you will need to plunge your toilet.

Now, if your pipes are clogged, this will result in the air coming out through the drain. You have to keep on plunging for a few minutes and then you can remove the cover from your bathtub drain.

sink-plunger

Try to flush the toilet again. The gurgling will likely be gone. If that is not the case, don’t worry, because I have more solutions for you.

4. Fixing the roof vent

This solution requires a bit more effort on your part than the previous ones, but it is highly effective and I sincerely doubt that you’ll have to be bothered with this problem ever again once you go through with it.

First of all, you have to climb to your roof and then find the opening of the main vent stack on the roof. Before you start, you have to clear the debris and the screen of the vent.

The vent pipe on your roof can easily become dirty since it’s very exposed and can easily become filled with leaves and other things that the wind or animals can bring down there.

After a while, this will result in clogging and, consequently, the gurgling noise from your bathtub drain.

A good solution for this particular situation is to bring a hose to the roof with you if that is possible and then pour spray the water from the hose into the vent.

This will clear up the debris and your problem will be solved. However, some complications may come up.

bathtub-drain-making-noise

If the blockage in the vent is too big, the water will back up out of the vent and you will not be able to clear out anything.

This is a situation where you should probably seek the help of a plumber or another professional because you will need to use a sewer auger which is not very easy to use and you probably don't have a sewer auger in your shed ready for a situation like this.

5. Unblocking sewer lines

Did you know that your sewer lines can be blocked by tree roots?

This is not a very common situation, but it does happen, and unfortunately, it usually requires the help of a plumber, since it's a bit more complicated to fix on your own.

If this is the case, your sewer lines will drain and this is when you’ll start hearing the gurgling noise.

how to soundproof a bathroom

All that you have to do in order to solve this is to clear out your sewer lines, but this is not a very easy task and it’s not the same thing as pipe cleaning, so you should probably call a professional to do it properly.

Final Word: Bathtub Drain Gurgles when Toilet is Flushed

All in all, we can all agree on one thing – the gurgling noise can be quite an annoyance and no one should put up with it for too long.

Luckily, now that you're familiar with the causes of the gurgling noise from your bathtub drain and with all the ways to fix it, I am hopeful that you will finally be able to use your toilet normally and relax.

If you come across this kind of problem ever again, you will be able to fix it and share this newfound skill with others who might need it. Good luck!