What is a Plumbing Vent and Why is it Important?

What is a Plumbing Vent and Why is it Important?

What is a Plumbing Vent and Why is it Important?

  • Introduction:

A plumbing vent is nothing more than a pipe that passes through the home’s roof and up to a plumbing fixture. You can typically see these vents sticking up on the roof of any residential building. To put it simply, this pipe permits the plumbing system’s air pressure to escape. 


Contrary to popular belief (and what many DIY explainers may claim), it is NOT primarily intended to allow air to enter the pipes. Consider this for a second: every drain in the house is open. In order to assist gravity in moving the water through the plumbing, air is easily able to enter the pipes.

Pressure, though, is the issue. Hazardous sewer gasses may accumulate in the plumbing system without a vent, which would make it more difficult for water to flow through the pipes effectively. The issue with a blocked plumbing vent is that it won’t let air out, not that it won’t let air in.

Why are Plumbing Vents Important?

Your sink, bathtub, and other home drains are connected to your drainage vents. Your attic is where the air vent pipe ascends before exiting into the outdoors through a hole in the roof. Drainpipes can be coupled to a re-vent that travels up and across to a stack vent or connected directly to a primary or secondary stack.

Without vent pipes, a vacuum effect would cause the wastewater draining down your drains to empty your traps. When this occurs, dangerous sewage gas leaks may enter your home.

As a result, you want a portion of the draining water to remain in the trap while the remainder to drain away. Your plumbing air vent permits air to remain between the trap and the draining water.

Vents, Traps and Suction:

Air and gravity work together to force water down the pipes as it drains. But they perform their duties almost too well. The majority of drains in a building include some sort of trap that creates a low spot in the drain that continues to hold water after the basin is emptied. 

This trap’s goal is to stop hazardous sewer gases from entering the house through the drain and perhaps making the occupants ill. The sewer gases inside the pipe are stopped by keeping the trap wet.

A suction effect will develop inside the pipe and draw too much water into the sewage line if there isn’t a vent beneath the drain to let air out when the water pushes through the trap. 

This frequently results in the trap being only halfway full, allowing those hazardous gases to enter the house. A healthy plumbing system therefore requires a vent that is operating correctly.

Can Drain Work Without a Vent?

Gravity pulls water from your drains and into your sewer lines. Your drains will function if your pipes slope downhill since the air in your room acts as a vent pipe.

The issue with using this drainage technique is that air can enter your home through your drain pipes. Your rooms are filled with foul sewer gases thanks to this air. Vent pipes prevent this from taking place.

What Causes Plumbing Air Vent Problems?

Your drainage ventilation may be compromised by a number of issues, which could result in hazardous wastewater overflows, hazardous gases, slow drains, and persistent gurgling and clogged pipes.

These are a few of the typical issues that lead to drainage vents failing:

  • Faulty Installation


Serious drainage issues may arise if you attempt to layout and install your own drainage system and vents or if you hire a novice to do so. Using a pipe requires a different size pipe.

The performance of your drains is also significantly influenced by the paths that they take through the wall framing and their pitch. In fact, a lot of people mistakenly believe their drains are clogged when a vent problem exists.

  • Frozen Plumbing Vents


Extreme cold might cause the plumbing vent stack that protrudes from your roof to freeze. The top of the stack becomes blocked when the water vapor inside the air vent freezes.

If this occurs, your drains’ pressure becomes unbalanced, which causes the water in your traps to be sucked out. Additionally, harmful gases like carbon monoxide, ammonia, and hydrogen sulphide as well as sewer gases might enter your home.

Enter your attic and wrap insulation over the vent pipe that leads to your roof to prevent frozen vent pipes. In order to get some warm air into the attic during freezing temperatures, you can also open the attic hatch.

  • Broken Vent Pipes


Your vent pipes and plumbing system could malfunction as a result of even a little leak brought on by corrosion and cracks. Smells can now invade your house as a result. Gurgling and sluggish drainage might also result from it.

To find any loose fittings, damage, or cracks in your vent piping, call a plumber.

Types of Plumbing Air Vent:

Plumbing codes can vary depending on where you live, even down to the type of vent pipe you can use. Find out which plumbing vent pipes you can use in your home by contacting your neighborhood plumbing provider. 

The following are the most typical plumbing ventilation choices:


  • Vent Stack


Vent stacks, often referred to as straight vents, are found in the majority of homes. The vents that pass through your roof are these. You can have a number of these vents on your roof, depending on how many drains you have in your house.

  • Wet Vent


Wet vents combine a drain and a vent into a single pipe. The use of these vent pipes is prohibited in several places. Wet vents typically involve drains that are close to one another, such a toilet and sink.

  • Air Admittance Valve


A small vent known as an air admittance valve or auto-vent typically attaches to a sink’s drain line. In order to maintain balanced pressure when draining, it allows air into the drainpipe. Instead of running a stack vent, many plumbers choose to use auto-vents. It costs less and uses less pipe.


Plumbing vent pipes and drains go hand-in-hand. Make sure your plumbing vent is installed properly, meets with local plumbing requirements, and is damage-free to keep your drains flowing quickly and smoothly. This will stop any water overflow issues and hazardous sewage smells from entering your home.

About Dutron Pipes and Fittings:

Dutron has been a leader in the industry of pipes and fittings for over 50 years and if you’re ever in need of anything related to pipes, fittings and plumbing, we’ll be more than happy to help you keep your loved ones safe!  


Feel free to contact us for any queries.