What If Your Under Sink Vent Not Working? Reasons And Solutions Here

As you are here, we can easily assume that your under sink vent not working probably. So, what could be the possible reasons? When you find suddenly the water flow in your sink is slower than usual, there must be a problem with the vent. It might be blocked with dirt, garbage, food waste, etc. Or the problem lies in the loop or air admittance valve (AAV).

And how would you fix this issue? No worries, this discussion sheds light on the common issue and shows you the path to resolve it.

Whatever the reason is, we came with a probable solution to help you out. Below, find the cause and a quick fix when you are in a tight spot with your clogged kitchen sink.

Under Sink Vent Not Working- What Could Be Reasons

Truth be told, there could be many reasons behind your sink suddenly stopping working. Among them, two primary issues can cause the kitchen sink vent clogged.

They are-

  • It’s clogged by food wastage, debris, or any other thing which is stopping the water flow
  • The failure of the air admittance valve
Clogged sink vent pipeClear the clog with a plumber’s snake
Issues in the AAVReplace the AAV

For both these issues, there are possible solutions. But first, you need to figure out the problems.

Check for Clog in the Vent Pipe

We all know that if the drain is blocked, you need to clear the blockage. But how? Well, for that, you can use a plumber’s snake to reach the blockage. A garden hose will be of much help to remove any further dirt or debris.

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However, You need to check actually where the clog is created. And to be sure if there is any clog or not, check the vent pipe inside with a bright light.

If you can locate the blockage, it would be much easier to push the clogs. Then, place the snake plumber deep down the sink vent pipe and instruct someone to connect the garden hose to the waterline.

A sudden water rush through it can clear all the blockage right away.

Check for Any Holes in the AAV

Secondly, the problem could arise due to the holes in the air admittance valve. Usually, an AAV maintains adequate airflow throughout the drainage system so that it could work without any hassle. So, if it goes bad, you will find the under sink vent not working. Either the drain will gurgle or it will be sluggish.

When too much water creates positive pressure on the AAV, it will be shut down automatically. So, where would the air go now? Having nowhere to go, they will create blockage inside the sink pipe and make the sink gurgle.

As already mentioned, if the problem arises from the holes, you need to concentrate on pest control. Because if you fix the issue by leaving the pests as they are, they are going to make holes further. So, it’s essential to find a way to control rodents.

After that, we suggest you replace the valve with a new one for better performance. Before that, make sure that there is no clog inside the valve itself.

In addition, there are some DIY tips for you regarding air admittance valves. You can try these before changing them.

Probably you are using too much water that’s causing the AAV not to work properly. So, if you face the problem of the kitchen sink vent not working, try to reduce the water flow.

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Also, you can run heavy water flow throughout the line to flush away all sorts of garbage. Repeat the procedure after every use to prolong the lifespan of the sink.

In this regard, we followed the following trick and got amazing results to make the sink work better. Using a bigger diameter pipe of 2″ will notably expand the pipe capacity. Besides, you can try using 20 DUF instead of 6 DUF to get a better service from the air admittance valve.

Nevertheless, if you are not sure where the problem is, ask for professional help. Expert plumbers are way better in this service. They will check the problem and solve it without affecting the drainage system in any way.

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Frequently Asked Questions (FAQs)

How do I know if my sink vent is bad?

If your sink vent is bad, there will be some signs to let you inform the issue. Firstly, the water will pass slower than on regular days. So, you can assume the issue from the sluggish water flow in the sink. Secondly, there will be gurgling in the water flow which indicates that our under-sink vent is not working properly.

Why is there a vent pipe under my sink?

The vent pipe under the sink is an absolute must to put a balance between the pressure put on the vent during heavy water flow. This pipe permits sufficient airflow inside the drain to keep it flowing. Without this sink vent pipe, the air could not be passed and could be clogged inside.

How do I know if my plumbing vent is clogged?


Finding an under sink vent not working suddenly is surely frustrating. But no need to worry as long as we are there. Our expert team has a solution for each of your household issues.

If you cannot call for a professional plumber immediately, try fixing the issue all by yourself. Mark the clog inside the plumbing pipe and run heavy water flow to push the debris away. Otherwise, check the AAV thoroughly and replace it if no problem is found.

Whether the under sink vent is clogged entirely or partially, it’s supposed to create gurgling or stop water from draining. Eventually, a foul odor would be there. Even harmful gas leakage could be an issue.

In order to keep all these dangers away, check your sink vent pipe on a regular basis and take immediate action if you find something off.

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