Kitchen Sink Gurgles When Toilet Is Flushed

If your kitchen sink gurgles when toilet is flushed, it may not seem like a big deal, but it can turn into a serious problem if left untreated. What does it mean when the kitchen sink gurgles when the toilet is flushed? The gurgling signs likely indicate that your pipes are not well vented, which can eventually cause slow water flow and possible water blockages.

Gurgling happens when the air passes through the sink’s P-trap, and if there is enough to empty that trap, there is nothing to stop harmful methane sewer gases from seeping through.

Clearing the vents may be a simple fix and may only require some toilet plumbing. However, if this problem has become more serious, you might need to hire someone to fix your pipes. Read on to find out more about your gurgling kitchen sink.

Gurgling Sink Mean

What Does a Gurgling Sink Mean?

A gurgling sink happens because air is seeping out from your drain. The presence of air in your drain is a problem in and of itself since the air causing the gurgling is coming from the pipes. This is why your kitchen sink gurgles when toilet is flushed. This is pushing or pulling the water into the P-trap in the drain.

If there is no clear air passage in the pipes, the air pressure will create more and more suction in the drain. This will force water down through the P-trap, which will amplify the sound of the air movement in the pipes. Also, as water starts to flow down the drain, it will continue to add more and more pressure and further obstruct the air passage.

There are many reasons for this, but usually, this is due to some sort of clog from grease, hair, etc., that should not have been flushed down the toilet or sink anyway. If they get stuck in your drain, they form a clog that causes an airflow problem. These subtle issues can go unnoticed, but their effects can be huge.


If a gurgling sink is not dealt with, it can grow into a severe plumbing issue. Because the gurgle represents an existing pipe blockage, more and more debris could get stuck inside that same blockage. If this happens and more residue seeps through, the clog or blockage will only grow and grow until your pipe is fully clogged. This will likely require some expensive repairs, which you will not be able to fix yourself.

How Do You Fix a Gurgling Kitchen Sink?

Step 1

You should fully close the sink drain, use duct tape to protect the overflow tubes, and then find a plunger. There will likely be some small blockage in the waste pipe that is flowing air via the sink drain. It will be best to use the plunger to perhaps remove some of the blockages. Closing the sink drain makes sure the plunger’s pressure is being applied solely to the pipes.

Step 2

Now, open the drain and keep flushing the toilet after you have finished plunging. If you still hear a gurgling noise, then plunge again. You should continue this process until you are absolutely sure that it is not alleviating the problem at all.

Toilet plunger with wooden handle

Step 3

If the plunging process has failed, then climb on top of the roof and examine the opening at your main vent stack. There may be some blockage from leaves or debris, or the vent screen might also be a bit dirty. You should scrape off all the leftover debris and cleanse the screen of any dirt.

Step 4

Now, you should find a hose to spray water down the vent pipe. If there is some sort of clog deep in the pipes, the water should get rid of it. However, if the water comes back up out of the vent when you spray into it, it is a pretty good indication that the blockage is a bit more severe. If this is the case, you should purchase a sewage auger to clear it.

A sewage auger can be easily purchased at a local hardware store or online.

VEVOR 50FTx1/2Inch Drain Cleaner Machine

Sewage Auger

A good sewage auger comes with a long wire cable that is both durable and long-lasting. It is flexible and adaptable to different fits but can also be easily controlled from different angles for easy navigation through a blocked drain. They are meant to be great for drain or plumbing vent cleaning.

Step 5

Now that you have your auger, you should unwind the auger into the vent opening until you feel some pushback. Then, it would be best if you started to crank the handle so the auger can work its way through the clog. It would be best if you pulled out the head every once in a while to clear any debris as well. Once you think you have gotten through the blockage, spray some water to make sure it does not spray back out. This will be a good indicator that the blockage is gone.

Step 6

Now, you should go and look under the sink to see if it still gurgles. If you see an air-admittance or ‘cheater’ valve secured to the P-trap arm, then unscrew it with pliers to replace it. It is a cheap component of your sink that a plumber sometimes installs if your sink has below-par venting, and it may be broken.

Frequently Asked Questions (FAQ)

Is a gurgling sink dangerous?

Yes, it is because although it may appear innocuous, a gurgling drain could cause a serious clog in your pipes. This could disrupt the plumbing in your entire house and perhaps even shut down water flow completely.

Why is my toilet gurgling on a septic system?

If your pipes make a gurgling noise, this will happen whenever you flush the toilet or run the tap. If your plumbing system is connected to a septic tank, this could indicate that your septic tank is full and needs to be pumped. The gurgling occurs when the septic tank is filled to the brim with solid waste and cannot then function at its optimal capacity.

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