Sink Gurgles When Washing Machine Drains (Help!)


Do you wonder why the sink gurgles when the washing machine drains? When using the washing machine, do you hear a strange sound coming from the sink drain? This sound is gurgling, and it most often occurs when the washer and sink share a drain.

Gurgling sinks can fill your sink with wastewater and sewer gas, which is a serious problem. It is most likely caused by partially clogged venting systems or clogged drain lines between the sink and machine.

As a result, the air gets trapped and builds pressure that pushes water, generating sound in the process; a gurgle. Venting pipes can fix the issue by allowing the air in the pipes to escape so that water can flow smoothly. 

For this reason, all plumbing fittings should be properly vented. Moreover, drains should be cleared off to prevent sewer gas from soaring into the sink and sluggish draining.

Why Does Sink Gurgle When Washing Machine Drains

Sink Gurgle When Washing Machine Drains

The elusive gurgle that comes from your sink when doing the laundry is one of these two things: the sink isn’t vented properly, or there is a clogged vent.

In the drain pipe, water from a draining washing machine forms an airtight seal. The water creates a vacuum, which pushes the air forward. As a result of this rushing air, your sink makes a gurgling sound.

If the dry vent is obstructed, air will flow up the pipe and move water along with it through the sinkhole. That is why you will find your sink filled with soapy water

Below are some possible reasons that cause sink gurgle when washing machine drains:

Wrong Type of Sink Trap

The gurgling sound, in most cases, is due to the selection of the wrong sink trap. It is most likely that you will have this problem if you have S-traps beneath the sink, which are now illegal. It is not vented, and water can come into the sink when you drain water from the washing machine. 

Unlike S-traps, P-traps have a wet vent that connects down to the main drain and goes up to the highest point.

Vent Pipes are Obstructed

There will be a common drain if your washing machine is near your kitchen or bathroom sink. Whenever there is a blockage in the vent pipes, this could result in gurgling noises. 

Due to the obstructed vent, the air in the vent will escape via the sink when the washing machine water drains, causing the gurgling sound. The air trapped in the pipes and sewer gas from the main drain will find its way to escape from the nearby sink. 

In most cases, sewer gas is vented out from the roof of the house through the vent pipes. If you want to establish whether your vent pipes are blocked or not, pay attention to the following: bad odors, the gurgling of the sink, and slow water drainage. 

Vent pipe leaks

As mentioned before, vents are used to maintain air pressure, but leaking vent pipes can cause problems in the smooth drainage. 

Due to the lack of proper air pressure, the air inside will not escape through the vent as it should but rather through the kitchen sink, which creates a gurgling sound when draining the washing machine. 

The air escaping through the sink creates a gurgling noise when draining the machine.

Vent Pipes Setup Issues

Another reason for a gurgling sink is the improper installation of vent pipes. For the functional setup, you should ensure that pipes are joined properly and that the routing of pipes is done in the correct manner. 

The sink trap connects to the main horizontal drain, which runs straight into the building drain. For a smoother transition, it is ideal to place a vertical vent pipe at a specific distance. It sucks air from the top and maintains air pressure, making sure the sink drains properly.

When the water from the washing machine is drained, it can cause gurgling if the vent is not properly positioned.  

Sewer line blockage

All wastewater is transported to the municipal sewer system through a sewer line. Your entire house will be affected when this pipe becomes clogged. A gurgling sound in more than one sink might be an indication of a sewer line blockage, not merely a clog.

Homeowners may find it difficult (or impossible) to fix a sewer line blockage. Repairing or replacing a sewer line requires the help of a professional plumber.

Central Vent Clogging

The last thing to look for is the main vent. 

The sink vent is connected to the central vent. If it is clogged, it can cause serious problems with drainage. The blockage in the main vent can build up air pressure, affecting the whole drainage system. 

When the washing machine drains, the air instead of moving out of the main vent gets trapped there. As a result, air will escape through the sink drain and make gurgling sounds.

How to Fix a Gurgling Sink When Washing Machine Drains

Many times, gurgling sinks occur because of issues with drains or sink pipes. Listed below are a few solutions you can try at home before seeking professional assistance.

Unclog The Main Vent

In most houses, the washing machine shares a vent with either the kitchen sink or a washroom sink. The main vent opens up on the roof, which can get clogged by the leaves, dust, or other forms of debris. Once blocked, it can affect air pressure inside the drain, leading to a gurgling sink.  

You should clean the debris, then use a pressurized pipe to blow water inside. It will clear out the main vent pipe. It should fix a gurgling sink, but if it doesn’t, move on to the next step. 

Fix The P-Tap

Most sinks have P-traps installed underneath. These are specifically designed to prevent sewer gas from coming up through your sink. 

Having a properly installed P-trap also effectively eliminates the gurgle issue of the sink. However, if it is not put in place correctly, it can lead to altered air pressure and cause the sink to gurgle.     

Studor Vent Replacement

The main vent is present in every house, while with every p-trap is a Studor vent, a mechanical air intake valve that absorbs sewer gas and prevents gurgling. In contrast, toilets do not use Studor vents since toilet vents require more air.

These vents are easy to install and, therefore, are preferred because of the fewer plumbing efforts needed. These vents also reduce the need for roof vent repairs. However, these vents also get clogged and affect the flow of the drain. 

You can either remove the debris from Studor vents or get the new ones as they are inexpensive. 

Use Drain Cleaners

Chemical Cleaners

If your gurgling kitchen sink is caused by buildup in your drains, purchasing a chemical solution is the best, simplest solution. In most cases, this is a simple fix, but ensure that you follow the instructions carefully. 

Despite their effectiveness at breaking down drain materials, these chemicals can be very harmful if they come into contact with your skin or eyes. Don’t let children or pets come in contact with them!

Enzyme Drain Cleaner

Drain cleaners that contain enzymes and bacteria help break down clogs and debris in your plumbing system. Additionally, mold and mildew will be eliminated

Compared to chemical drain cleaners, enzyme drain cleaners pose fewer risks of damage to your plumbing system. However, these cleaners take more time to get rid of clogs. 

The enzyme drain cleaners usually require you to pour the enzyme down the drain in the evening before you go to bed. In the morning, flush the drain.

Baking Soda Application

Another organic way to clean the drain is the use of baking soda. All you need to do is pour one cup of hot boiling water into your sink. Then, pour one cup of baking soda afterward. Getting the baking soda into the drain isn’t easy and takes some effort.  

Finally, add one cup of vinegar and plug the drain up. After 10 minutes, the chemical reaction between baking soda and vinegar will loosen the residue from the drain pipe. To flush away these residues, rinse the drain with boiling water.

Clear The Draining System

The easiest way to fix this is by running hot water down the drain after verifying your p-trap, roof vent, and Studor are all working.

It is possible that there is a small clog in your drain that is causing your sink to gurgle. If that is the case, the drain can’t take more water, and it will produce a gurgling sound. Gradual build-up of clogs can cause clogging of the drain.  

A gurgling sink and slow draining water are all signs of a blocked main drain. You can remove these clogs in an effective and eco-friendly way by using various cleaners. Poring these clog removers in the drain overnight can break down soap particles and other debris. Finally, flush these waste materials. 

What to Do If Utility Sink Filling with Waste Water

Water keeps filling up your utility sink every time you use it, which can be caused by a variety of factors. As a starting point, you should consider three things: sink trap, venting pipe, and drain.  

Traps are installed underneath the sink. Find out which kind of sink trap your plumber has used. If it is S-trap, you probably need to replace it.

In the case of the P-trap, you should look at whether it is installed correctly or not. Next, clean it to remove any clogs that may be preventing it from working.   

In case the problem persists, check the vents. If you do not vent your drain, you may hear the gurgling sound, and wastewater may rise into the sink.

In the absence of the vent pipes, you can use Studor vents. It will keep the air pressure balance and allow a smooth transition of water into the drain. 

Lastly, make sure the main drain is working properly. It usually gets blocked, trapping air inside. You can use chemicals to remove the blockage. Pour these cleaners into the drain and overnight. These chemicals will break down the blockages into small residues, which can be flushed out using boiling water.    

Why Gurgling Sound Even When Not in Use

The sink might even gurgle if it is not even in use. As most of the sinks share vent pipes with either toilet, bathtub, or washing machine drains. Now, if there is poor venting or a partially clogged drain, it will affect the slug of water flowing.  

All the small vents open into the roof or central vent system. Sometimes, this main vent gets blocked with dust and debris. This result in the trapping of air, which can create a vacuum. 

As the trapped air tries to escape, it makes gurgling sounds in a sink that is not being used.

The second reason may be the blockage in the main drain pipe. All the vents and draining pipes open up into the main drainage line. The obstruction in this pipe means the sewer gases and the air already trapped can’t escape. 

Through the sink trap, air finds its way into the sink as it tries to find its way up. In the process, it produces a gurgling sound that you may even hear in the sink that is not the use.    

Can The Washing Machine Drain into A Sink?

Yes, your washing machine can drain into a sink. You can use a utility sink for handwashing garments, washing hands, and other tasks. You can use this sink to drain a washing machine.

You can attach a washing machine’s drain hose to your sink if you have suitable fittings. Sink drains must be large enough to handle the volume and pressure of a clothes washer’s drain pump.

There will be no gurgling if the plumbing is adequate, and neither the vent pipe nor the main drain is blocked.

Does Washing Machine Drain Need a Vent?

You need venting for all plumbing equipment, including washing machines. Drains that are not properly ventilated can be noisy, and they may also produce dangerous fumes.

Drains that are not vented make it impossible for the P-trap to perform its intended function. It prevents sewer gases from entering your home.

Significant amounts of water can produce a siphoning effect. Pulling water and harmful gases out of the trap and into the atmosphere if the venting system is not functioning correctly. This can be dangerous.

Key Takeaway

You may hear the washing machine drain pipe gurgling. This is the air leaving the drain, which is trapped inside the pipes where it is exerting pressure.

If your kitchen sink gurgles while the washing machine drains, this indicates that something is obstructing the flow of water. If your washing machine drains, your kitchen sink should not gurgle.

An obstruction and the air pressure it creates can cause suction in the drain if the passage is not completely clear for airflow. As it passes through the blockage, it applies additional pressure as it pulls on the water in the P-trap, creating an audible air movement. This is why pipes gurgle when the washer drains. 

Several factors contribute to the sink gurgling when the washing machine is on. It is most common that sink traps are chosen incorrectly, vent pipes clog and leak, drains are obstructed, and fittings are installed improperly. 

If a gurgling sink isn’t fixed, it can grow into a much larger plumbing problem. You can fix the gurgling sink by selecting the right sink trap, unclogging the main vent, fixing P-trap, using drain cleaner, and clearing the drain. 

A professional can assist you if you aren’t confident doing it on your own.

Lisa Burks

This is Lisa Burks, the Author. I provide free informative sink and faucet guides. I hope you love your time here.

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