Why Your Toilet Gurgles When the Washer Drains & How to Fix It

If you’re reading this, chances are you’ve noticed a strange occurrence: when your washing machine drains, your toilet starts to gurgle, or you see air bubbles rising.

This phenomenon can be frustrating, but the good news is that it’s something you can likely fix yourself with the right knowledge. In this guide, we’ll walk you through the causes of this issue and provide you with step-by-step solutions.

Understanding Your Plumbing System: A Quick Overview

When your toilet gurgles whenever the washer drains, finding the culprit can sometimes be tricky. That’s why having basic knowledge of your plumbing system will go a long way in helping you trace the problem.

With that said, let’s think of the plumbing system in your home as a network of roads where water and waste travel along different routes.

When water from sinks, toilets, or the washing machine drains, it flows through a series of pipes that eventually lead to your main sewer or septic system.

Now, there’s something called a vent stack—it is typically a pipe that extends from your drainage system up through your roof. It’s job? Is to let air into the system. Without this airflow, water can’t move freely through your pipes.

What happens is when water rushes down a drain, it creates a negative air pressure behind it. That’s why the vent stacks are there to maintain proper air pressure and it does it by allowing outside air to enter the system and balance the pressure so the wastewater can flow smoothly.

The Relationship Between Your Washing Machine and the Gurgling Sound

Your washing machine is unique among household appliances because it discharges a large volume of water, and it does it quickly—typically around 10-20 gallons in just a couple of minutes. And as a result, the sudden rush of water creates pressure in the system.

In a normal functioning plumbing setup, the water would flow freely down the drain pipes while the air from the vent stack balances the pressure.

But, if there’s something wrong with either the vent stacks or the drainpipes, that powerful surge from your washing machine can disrupt the whole system—which can lead to the gurgling sound you hear or the bubbles in your toilet.

Why Your Toilet Bubbles or Gurgles When the Washer Drains

Great question! You see when your washing machine dumps all that water into the drain, it creates a strong negative pressure (a vacuum) behind the flowing water.

As we mentioned earlier, in a normal system, the vacuum will get filled by air coming down through your vent stack.

But when something goes wrong, and the normal airflow is obstructed, the system gets desperate and looks for air elsewhere.

The nearest source of air is often through other drain openings in your home, like your toilet. So, as air is being pulled through the water in the bowl, it creates the bubbles you see and the gurgling sound you hear.

Toilet Whistles When Flushed: 5 Easy Ways To Fix It Forever

Toilet Gurgling Causes & Solutions

Common Causes of Toilet Gurgling During Washer Drainage

Now that you understand how your plumbing system works let’s look at specific problems that might be causing your toilet to gurgle whenever you drain your washing machine. By identifying the exact cause, you’ll be better equipped to fix the problem.

1. Partial Clogs in the Drain Lines

Over time, hair, soap scum, grease, and other debris can build up on the inside walls of your drainpipes. Unlike a complete blockage (which would cause an immediate backup), partial clogs create a narrowed way that still allows air to flow through, but at a reduced rate.

So, what happens is, when your washing machine discharges its large volume of water into these partially clogged lines, the water can’t flow through fast.

That creates a bottleneck effect where water backs up temporarily behind the clog, pushing air elsewhere in the system—which is often through your toilet.

Signs of a partially clogged drain line

• Your toilet gurgles only when the washing machine drains—not at other times
• Sinks or showers might drain more slowly than they used to
• The gurgling might stop and start as the washer goes through different drain cycles
• Problems might become more frequent or severe over time as the partial clog worsens

2. Blocked Vent Pipes

As we discussed earlier, your plumbing vent is important in maintaining proper air pressure in your drainage system. So, when your vents get blocked, air can’t enter the system normally, forcing it to find another way with the least resistance, and that’s through your toilet.

When that happens, you might notice bubbles in your toilet or hear gurgling sounds (or even both).

Signs of blocked vent stacks

• Leaves, twigs, or other debris that fall into the open pipe on your roof
• Birds, squirrels, or other animals building nests inside the pipe
• Ice or snow accumulation during winter months (especially in colder climates)
• Spider webs or insect nests that build up over time
• An improperly installed vent cap that restricts airflow

And since vent stacks exit through your roof, you might not notice a problem until your fixtures start gurgling.

3. Improper Washing Machine Drain Installation

When installing washing machines, it’s crucial to do so with proper drainage considerations. For example, the drain hose from your washing machine should not be pushed too far down into the standpipe (i.e., the pipe where your washer drains).

Most manufacturers recommend that the drain hose should only be inserted 4-6 inches into the standpipe.

But what happens when the pipe gets pushed too far down? If that should happen, it can:

• Create a siphoning effect that pulls water from the P-trap (i.e., the curved pipe segment under sinks and fixtures that holds water to block sewer gases)
• Block air from entering the drainage system
• Create excessive pressure when the machine discharges water

Another common installation issue is a missing air gap or improper venting at the washing machine drain. This air gap is necessary to prevent backflow and allow proper pressure equalization.

Signs of improper washing machine installation

• The gurgling started after a new washing machine was installed
• You recently moved your washer to a different location in your home
• Someone recently made changes to your plumbing system
• The problem occurs consistently with every wash cycle from the very first use

4. Main Sewer Line Issues

Your main sewer line is the primary pipe that carries all wastewater from your home to the municipal sewer system or your septic tank.

When this line develops a clog or blockage, it creates problems throughout your entire home—not just in one fixture alone.

A main sewer line clog is more serious than a simple drain clog because:

• It affects all fixtures in your home, not just those near the washing machine
• It can lead to sewage backing up into your home
• It won’t resolve itself and typically requires professional intervention

In addition, the large water volume from your washing machine can make an existing mainline problem more apparent because it puts additional pressure on an already compromised system.

Signs of a main sewer line issue

• Multiple fixtures gurgling, not just the toilet nearest to your washing machine
• Sewage backing up into tubs or shower drains (these are typically the lowest fixtures)
• Toilets that overflow or back up when you run the washing machine
• Persistent plumbing issues throughout your home
• Strong sewage odors in or around your home

5. Shared Drain/Vent Systems

In many homes, especially older ones, multiple fixtures may share the same drain line or roof vent stack. While this design can work properly when everything is functioning correctly, it leaves fixtures susceptible to affecting one another.

For example, when your washing machine and toilet share a common drain line or vent:

• The large volume of water from the washer can momentarily overwhelm the shared line
• Air pressure disruptions affect all fixtures on that line
• The toilet becomes the “weak point” where air and pressure find release

This is actually a normal occurrence in many plumbing systems, but it becomes problematic when combined with any of the other issues we’ve discussed.

Now that you know what is possibly causing your toilet to gurgle whenever your washing drains, it’s now time to solve the problem.

How to Fix Your Toilet Gurgling When the Washer Drains

1. Plunging the Toilet (for Partial Clogs)

Plunging your toilet is usually the first and simplest solution you can try to fix a toilet that’s gurgling, especially when you suspect a partial clog in the toilet drain. If that’s the case for you, then you’ll need:

• A toilet plunger (get a flange-type plunger with an extension that fits into the toilet drain)
• Rubber gloves
• Old towels for potential splashes

Once you have all that ready, do the following:

• Put on your gloves and place the old towels around the base of the toilet to catch any water splashes
• Make sure that there’s enough water in the bowl to cover the plunger’s rubber cup. You can add water if needed
• Now, place the plunger directly over the drain hole in the bottom of the toilet bowl. When you do that, make sure that the flange extends into the drain opening for a good seal
• Next, gently push to expel air from the plunger’s bell. This action prevents forceful air from pushing dirty water back at you
• Start using deliberate, vertical strokes with consistent pressure. Push down and pull up with equal force
• Now, slowly build momentum. Aim for about 10-15 plunges in a row
• Finally, after plunging, flush the toilet and run your washing machine through a drain cycle to see if the gurgling has stopped.

If it has, congratulations! You have fixed your gurgling problem. If not, move on to the next step.

2. Clearing Partial Drain Clogs

Since plunging didn’t solve the problem, it could mean that there are clogs hidden deep in your drain lines.

For that, we’ll need a hand auger (sewer snake), rubber gloves, protective eyewear (if available), a bucket, and old towels.

Once you have those ready, follow these steps to clear partial clogs in your drain using a toilet auger:

• Put on your gloves and place the towels around the base of the toilet
• Now, insert the curved end of your auger into the toilet bowl
• Turn the hand crank clockwise to extend the cable into the drain. Continue cranking until you feel a resistance (likely the clog)
• Once you hit the resistance, crank it slightly with more force or try alternating between pushing forward and backward. You mean feel the cable break through the clog or wrap around it
• Now you have worked through the resistance, slowly crank counterclockwise to remove the snake
• Finally, flush the toilet several times to clear any loosened dirt. Next, run your washing machine again to see if the gurgling stopped.

3. Inspecting and Clearing the Vent Stack

If you suspect that a blocked vent is the reason behind the gurgling you hear, then you have to clear it. To do that, you’ll need:

• A sturdy extension ladder that’s higher than your roof
• Non-slip shoes
• Gloves
• Someone to stabilize the ladder

Once you have all that ready, follow these steps:

• Place your ladder on a firm, level ground and extend it at least 3 feet above the roof edge
• Have someone hold the ladder while you climb
• Walk gently on the roof to avoid damaging the shingles. If you have a steep roof, then it’s safer to abort and hire a professional to handle it instead
• Once you get the vent stack, flash a torch into the vent pipe and look for visible blockages
• If you find blockages like twigs, leaves, or nesting materials, you can use your hands (with your gloves on) if within arm’s reach otherwise, you can use a reacher tool or pliers to remove them
• And if you see an animal nest or hear sounds that make you believe there’s a bird’s nest, it’s best to call animal control or a professional plumber instead of trying to do it yourself
• After clearing the clogs in your vent, run your machine and see if you can still hear the gurgling sound.

4. Checking Washing Machine Installation

If your washing machine is not properly installed, it can cause pressure issues in your plumbing system. Here’s how to check for installation gaps and address them:

• Your washing machine drain hose should form a U-shape and connect to the standpipe at a height of 34-36 inches from the floor. This is important because it creates the necessary air gap
• Next, the drain should only extend about 4-6 inches into the standpipe. If it’s inserted too deep, it can cause siphoning and pressure problems. If that’s the case for you, you can just pull it back until only about 4-6 inches is inserted
• Also, make sure that your drain hose isn’t kinked, bent, or compressed anywhere along its length. So, if it’s kinked, cracked, or damaged, you may have to replace it—follow the instructions in your manual to help you get the right part
• Then, check the standpipe. It should be 2 inches in diameter and at least 30 inches tall to prevent overflow

After checking and making the above adjustments, run your washing machine through a drain cycle to see if the goggling has stopped.

If it has, congratulations! You have finally cracked it. If not, then it’s high time you consider calling for the services of a professional plumber, most importantly when you suspect a main sewer line problem.

Toilet Makes Hissing Sound: 7 Easy Ways To Fix It Now

Paul Wilson( Licensed Plumber )

Paul Wilson is a highly skilled plumber with over ten years of experience in the industry. He holds an IDPH license and takes pride in his ability to tackle many plumbing issues and successfully complete even the most challenging projects.