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What Is A Plumbing Vent And Why Is It Important In A Plumbing System?

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

Plumbing vents protect your family from dangerous sewer gas. Your home’s plumbing vent system keeps your drains open and protected from clogs.

You should always check your home’s plumbing vent system before calling a plumber.

What Is A Plumbing Vent?

Plumbing systems play a large role in our homes. We use up to 100 gallons of water each day. Our pipes carry water from the faucet to the toilet.

We need to know how to diagnose and sometimes fix them if we want to avoid costly repairs.

Your drain pipes connect to your sinks, tubs, and other household drains, and then run up into your attic.

Air vents go up into your attic and then out into the open air. You could also use an exhaust fan instead of a vent.

Plumbing systems consist of two main parts, the drains, and the supply lines. Drains carry away waste and water while supply lines bring water into your house.

You need both types of pipes when you want to use the bathroom sink (see also ‘What Is My Bathroom Sink Made Of?’), shower, tub, toilet, etc.

Vent pipes work alongside your drains, but they don’t carry water. Instead, the vent pipe regulates the air in your plumbing system.

The vent pipe helps waste and water flow through pipes that drain out of your house. It prevents vacuum that causes slow or no drainage.

Clean drains require ventilation. Ventilation allows clean air into the system. A clogged drain causes dirty air to enter the system. Dirty air causes clogs.

Clogs cause leaks. Leaks cause damage. Damage causes repairs. Repairs cost money.

Money costs time. Time costs energy. Energy costs fuel. Fuel costs gas. Gas costs money. Money costs time…

Your plumbing vents’ second purpose is to remove sewage gas. Sewer gas flows into your home via your plumbing vent pipes.

Plumbing vents are installed away from air conditioners and windows so that you won’t smell or see any sewer gas coming back into your house.

Plumbing vents let air stay between the draining and trapping water. This prevents the sewer gas from entering the house.

Water and waste flow out of your house and into the sewer system when you flush the toilet.

What Is Sewer Gas?

Sewer gas comes from human waste. Waste contains bacteria and germs that can make people sick.

If you don’t have a working plumbing vent system, these germs will flow back into your home.

Sewer gas smells bad because it’s made up of methane, hydrogen sulfide, carbon dioxide, ammonia, and other chemicals.

These gasses mix together to form sewer gas. The mixture makes sewer gas stink.

Common Types Of Plumbing Vents Pipes

Plumbing fixtures should be installed correctly. Venting is important. A true vent is used when installing a sink (see also ‘How To Install Vent Under Sink’) or other plumbing fixture.

Common vents connect pipes together, while re-vents connect pipes to the roof.

Air admittance valves let air in and use gravity to stop any gasses in the room.

These vents usually open for more than one fixture, but make sure to check building codes before installing them.

Potential Vent Pipe Problems

Blockages in your vent pipe can cause a buildup of negative air pressure in your drainage system, making it hard for water to drain out of your house.

A blocked vent may be the cause. You should call an expert as soon as possible to get this fixed.

You should always call a plumber as soon as possible when your pipes start backing up. Sewer gas smells bad, and it can be deadly.

Standing water in sinks and tubs can be a serious health hazard. If you notice any other problems, call a plumber right away.

Plumbing problems should be fixed by a professional plumber.

A plumbing problem could be caused by many things, but most likely it is due to clogged drains, broken pipes, or leaky faucets.

How Does A Typical Drain Work?

Plumbing systems need traps under drains to prevent odors and gasses from entering your house. Traps hold water, which keeps smells out of your home.

If you don’t use a drain often, the water in your trap can evaporate. You’ll notice a sewer smell in your room when this happens.

Your drains should be placed downwards to prevent air from entering them. If you use a vent pipe, make sure there is no air in your house.

Negative and positive pressures cause siphons. Vent pipes neutralize them.

What Causes Plumbing Air Vent Problems?

Drainage (see also ‘What You Need To Know About Gutter And House Drainage Distances‘) venting systems are very important for keeping water out of your house.

There are many different types of plumbing fixtures that you may use in your home. Some of these include toilets, sinks, tubs, showers, faucets, etc. 

All of these plumbing fixtures require proper maintenance to ensure that they function properly. You should contact a plumber if any of these issues occur.

Improper Layout And Installation

Improper Layout And Installation

Drainage systems should be installed by professionals who know what they’re doing. Your pipes may vary in size depending on how much water you use.

Routes through your walls and pitches of your drains also affect your drains’ performance. A drain may appear clogged when it’s actually a vent problem.

Plumbing codes vary by region. For example, in some areas, it is illegal to install a pipe at a certain angle.

In other regions, it may be illegal to install a pipe without a vent. Always hire a plumber who understands local plumbing laws before starting work.

Frozen Plumbing Vents

When the temperature drops below freezing, you should check the vents on your roof. You may need to clear snow or ice from them before winter weather hits.

Make sure there aren’t any leaks around the vents. If you see any problems, call a plumber right away.

To prevent frozen vent pipes, you should wrap insulation around the vent pipes that go to your roof.

You should also open your attic hatch when it gets cold to let some warm air inside.

Damaged Vent Piping

Cracks and corrosion in the vents allow smells to enter your home, causing gurgling and slow water drainage. A plumber should be contacted to fix these problems.

Clogged Plumbing Air Vent

A clogged vent pipe can cause smells and slow drains. You can use an auger or snake to remove clogs.

Plumbing services use industrial strength snakes (see also ‘How To Use A Plumbing Snake‘) to remove clogs.

What Are The Types Of Plumbing Air Vents?

Plumbing vents include different types of piping systems. You need to know what type of system you want before you buy or install them.

Your local plumber should be able to help you choose the right plumbing vent option.

Vent Stack

Most homes have vent stacks, or direct vents, which are the vents that go through your roof. You may have more than one vent stack on your roof.

Vent stacks are used to release hot air out of your house.

Wet Vent

A wet vent is both a drain and a vent in one pipe. These vents are often used in bathrooms or kitchens. Some places restrict the use of wet vents.

Air Admittance Valve

Air admittance valves let air into the pipes, but they also let water out. This makes them useful for keeping drains clear.

Plumbers often use these vents because they cost less than running a stack vent.

The Importance Of Plumbing Venting

Plumbing venting (see also ‘3 Signs You Have A Clogged Plumbing Vent And What You Need To Fix‘) is an important aspect of maintaining a healthy home. Plumbing venting is important because it allows air to flow freely throughout your house.

Venting also prevents moisture buildup inside walls and ceilings. You should always check the condition of your vents before you use them.

This is especially true if you are planning to remodel or add insulation to your attic.

You need to be aware of what happens when water gets into your house. Water should never get into your home.

When you use your bathroom, shower, kitchen sink, laundry room sink, tubs, toilets, etc., make sure that the pipes leading out of these fixtures are properly vented.

This prevents moisture from entering your home. Also, if you notice any leaks around your home, call a plumber right away.

Release Of Pressure

Vents allow air pressure to escape through the plumbing system. Most homes have them, but they aren’t used for letting air into the pipes.

Plumbing vents allow air into homes but also release pressure in the plumbing system. This allows for easy flow of water.

If there aren’t any plumbing vents, dangerous sewer gas builds up and makes it harder for water to move through the pipes.

A clogged vent is a big problem because air can‘t escape, not because air can’t get in.

Gravity Air And Traps

Home drains should be cleaned (see also ‘How To Clean The Drains In Your Home‘) regularly to prevent clogs.

Traps should be checked often to ensure that they’re working properly. Sewer gas shouldn’t enter homes because it could cause health problems.

A plumbing vent system vents air as water goes into the drain so water stays there instead of going elsewhere.

Avoid Risks To Health

Plumbing vents prevent dangerous gasses from finding their way into your house by preventing a suction effect.

You must ensure that all the plumbing vents meet in the attic. This prevents dangerous gasses from entering your house.

Suction is caused by water getting sucked into the sewer line. This makes the air inside the house become more dense than normal air.

As a result, you’ll feel stuffy and have trouble breathing. Your home won’t be free of this risk if you don’t install proper venting systems.


Plumbing vents should be checked regularly. If they’re clogged up, you’ll notice problems with your entire drainage system. You need to check your pipes every few months.

When blocked, potentially dangerous compression builds up. Don’t wait until the smell of sewer gas reaches you. Call an expert plumber to fix it as soon as possible.

author avatar
Charlie Hardcastle


On Key

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Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases. When it comes to dealing with clogged drains, many homeowners turn