Toilet Gurgles When Washing Machine Drains: Causes and Fixes

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A gurgling toilet indicates that there’s something wrong with your drain system.

This means that there’s a pressure difference in your toilet waste line that is sending air directly into your toilet bowl, and, that’s why it gurgles.

But, it doesn’t have to mean that your toilet waste line is malfunctioning. In some households, the toilet drain system is connected to the washing machine drain system.

And, there might be a pressure difference in the drain system, which means that your toilet waste line is functioning properly.

In that case, you should definitely act on this problem and have it fixed as soon as possible. This can create numerous hygiene issues if it progresses.

So, let’s see how this happens and what can you do in order to fix it.

Toilet Gurgles When Washing Machine Drains

Toilet Drain Connection

As we already mentioned, there are some drain systems that are connected with your toilet waste line.

So, if you are not certain about the washing machine drain being connected to the toilet waste line, you should just pay more attention when you wash your clothes.

If you notice that your toilet is gurgling when you wash your clothes, you can definitely be certain that these two drain systems are connected. Configurations like this one are not unusual.

Now, the connection between these two drain systems might be located somewhere between the toilet and a soil stack. In that case, the washing machine drain ties directly into a toilet drain.


On the other hand, the connection might be located in the same vertical stack. This means that these two drain systems share the same venting.

Never the less, in both cases, your toilet drain is connected to the washing machine drain and that’s where pressure difference occurs. So, the real question here is what causes pressure difference and gurgling?

Well, let’s find out.

Toilet Gurgles When Washing Machine Drains

Venting Problem

So, the problem might occur when your vents are blocked. It doesn’t have to mean that only fully blocked vents can cause toilet gurgling, partially blocked vents are problematic as well.

Anyhow, blocked vents are creating negative pressure which then pulls air from any possible source. Simply speaking, the water that flows inside your drains will form an airtight seal which will push air in order to create a vacuum behind.

So, it all depends on how much the vent is blocked since the vacuum effect can be enough to pull the air through the toilet which will then create that gurgling sound that you heard.

However, if the blockage is minor, you won’t hear any gurgling, but there’s a chance for that blockage to grow.

gurgling toilet connected to washing machine

On the other hand, if the vent blockage is severe, that means that you are definitely going to hear a lot of gurgling sounds when your washing machine starts washing.

In both cases, it is extremely important to deal with it immediately.

Why? Well, gurgling is definitely not a thing that you want to hear in your toilet bowl.

Since the toilet is designed to have a bit of water sitting in the bowl, gurgling and pressure difference can create that vacuum effect which will pull the water out of the bowl.

That can lead to a sewer gas explosion and your bathroom will not be a safe place to be in.

Washing Machine Drain Installed Improperly

In most cases, improper washing machine drain system is a reason why you are experiencing gurgling in your toilet. How is that connected? Well, there are a couple of scenarios in this particular situation.

1. Water Release

First of all, a washing machine will release a huge amount of water when it washes clothes. Now, that water must be released under high pressure, and that’s exactly why the pressure difference occurs.

Namely, since the washing machine releases water under high pressure, there won’t be any room for air to enter the pipes. That leads to a pressure difference and the air that already is in the pipes will find its way to the toilet bowl.

That will create a gurgling noise inside your toilet.


2. Poor Connection

On the other hand, poorly connected pipes are also a reason why you might hear gurgling in your toilet bowl.

Simply put, if the connection pipes between toilet and washing machine drain systems are not properly connected, the pressure will be low and the air will start exiting through the cracks.

This is usually followed by some leaks, but, in this case, air will leave through the toilet bowl which will create the gurgling noise.

3. Undersized Pipes

The use of undersized pipes will create a similar scenario like the high-pressure water release. If the pipes are narrow and there’s a lot of water that needs to flow through these pipes, the pressure will be high and the air will be forced.

In that case, air will exit through the toilet bowl and that’s exactly how a gurgling noise occurs inside your bathroom.

How to Stop Toilet Gurgling Noise

There isn’t a simple solution to toilet bowl gurgling if the problem lies inside a washing machine drain. Now, solving these problems depends on the reason, so here are some solutions:

Improper Drain System Installation – If your washing machine drain system is not properly installed, you will experience some other problems as well, like leaks.

So, it is definitely the best solution to call a professional to handle this kind of a problem. You can try doing it yourself, but that will require you to properly install a 2-inch drain with a P-trap.


Venting issue – On the other hand, if your plumbing systems are perfectly installed, then you must be experiencing venting blockage. In that case, you will need to remove that blockage with a thorough plunging.

A partial toilet waste line blockage can create venting blockage as well, and that’s why your toilet gurgles.

Conclusion: Gurgling Toilet Connected to Washing Machine

In light of everything we mentioned here, it is only logical to conclude that gurgling inside a toilet bowl is a serious problem. Anyhow, we have explained everything thoroughly about the gurgling and how it occurs.

Now, it is up to you to deal with it. Just remember, these tips that we provided can be a real game-changer.

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