3 Signs Of A Clogged Plumbing Vent (What Should You Do)

Plumbing vents are commonly clogged from debris that falls onto your roof. Vermin such as birds, mice, and squirrels create nests in or around pipes, blogging off airflow and causing an issue with your plumbing vent.

If you are experiencing gurgling noises when you flush the toilet, slowly draining water, or smell a strong sewer odor in your home, you may have a clogged plumbing vent. 

Plumbing vents are an important part of your home plumbing system. Knowing how to take care of your plumbing vent is an important part of home ownership. Learn how to identify a clogged plumbing vent and how to fix it quickly and safely.

What Are Plumbing Vents?

Plumbing vents are pipes that run from your sewer line up through the roof of your house. Plumbing vents regulate the pressure within plumbing pipes.

Toxic sewer gases like ammonium and hydrogen sulfide are pushed out of the pipe and into the outside air. This prevents noxious sewer gases from leaking into your home. It also regulates the flow of water throughout your home plumbing system. 

How plumbing vents work

Plumbing vent pipes are usually made from PVC. Maintaining your plumbing vent is essential for efficient water flow.

Plumbing systems have p-traps or low points in pipes. P-traps prevent gravity from pulling all the water through the pipes and into the sewer. By trapping water in the p-trap, sewer gases are sealed in and cannot leak out through the drains or water taps in your home.

What Causes a Clogged Plumbing Vent?

Plumbing vents come out through your roof and are exposed to outside elements. Most clogs are a result of debris and animals. Fall leaves and small tree branches can get stuck in the pipe or cover the pipe opening, clogging the plumbing vent.

Animals can also create nests in or around plumbing vents. It is important to keep birds, squirrels, and vermin off your roof and away from the plumbing vent. Small animals like mice or snakes can even make their way down the plumbing vent. This will cause a serious obstruction that can severely harm your plumbing system.

Signs That Your Plumbing Vent is Clogged

A clogged plumbing vent causes unequal pressure between the interior of the pipe and the exterior of the pipe. This causes water flow and draining issues within your home.

The most obvious hint that you have a clogged plumbing vent is if a smell like rotten eggs permeates through your home. Other plumbing problems that can be attributed to a clogged plumbing vent include gurgling toilets, empty toilet tanks, and slow draining.

1. Spluttering and gurgling toilets

If your plumbing vent is blocked, airflow is restricted. Air cannot easily flow through your pipes. There will be a delay from when the water flushes down the pipe and when the air follows behind it. The air is supposed to fill the vacuum left by the water.

When it takes longer for the air to get down the pipe, you will hear a spluttering or gurgling noise. Spluttering is a sign that the pressure inside your plumbing pipe is higher than outside of the pipe. This causes water flow issues and can seriously damage your plumbing. 

Gurgling toilets

Spluttering and gurgling can also be caused by drain clogs. Try to dislodge a clog with a plunger before assuming the issue is your plumbing vent. If you have more than one bathroom, check to see if the issue is occurring with each toilet. If your plumbing vent is clogged, you will have a problem with every toilet. If it is a regular clog, only one toilet is affected.

Blocked plumbing vents can also cause empty water tanks. Because air can’t get through the pipes and equalize the pressure, all of the water will flow into the sewer. It will not be able to stay in the toilet tank. If you go to flush and realize there is no water in your toilet, you may have an issue with your plumbing vent.

2. Strong sewer odor

When plumbing vents are clogged, water will not flow properly. It also causes the p-trap to drain dry. This will cause sewer odors to flow up and into your home. P-traps are designed to hold small amounts of water.

This creates a sealant that traps sewer gases in the pipes. Without water in the p-trap, gases will escape out through the floor and sink drains. Ammonia and hydrogen sulfide will flow into your home giving off a foul smell. These gases are extremely toxic and will cause health issues if not addressed quickly.

Blocked plumbing vents can also cause methane gas from flowing out of your pipes into your home. Methane is colorless and odorless. Inhaling methane causes headaches, nausea, and fatigue. If members of your family are experiencing these symptoms, proceed with caution and check your plumbing vent for a blockage. It is not safe to inhale methane or sewer gases.

3. Slow draining

Slow-draining water can be caused by several problems in your plumbing. Usually, it means you have a block in one of your pipes. This can be easily addressed with drain snakes or chemical solvents.

To determine if your slow-draining water is a result of a regular clog or an issue with your plumbing vent, test multiple drains throughout your home. Blocked plumbing vents will cause problems with every drain, not just one. Also, check for a strong sewer odor and gurgling toilets. A combination of a slow drain plus one of these other issues will point to a problem in the plumbing vent.

Slow draining Toilet

Clogged plumbing vents cause slow draining because of the unequal pressure in the pipes. If not enough air is going through the plumbing vent, the water cannot be pushed through. This will cause water to drain slowly. It may even cause back flowing where the water will drain from one area like a sink, but push up through another drain like the bathtub. 

How to Unclog a Clogged Plumbing Vent

A plumbing vent is usually caused by an issue outside. Leaves or debris can call into the pipe that is pushed out through the roof. The buildup of leaves can cause a block at the pipe’s entrance. Clogs can also be caused by animals.

You need to remove whatever is blocking the plumbing vent to get air to flow properly and equalize the pressure again.

Be careful when unclogging plumbing vents. Gases are built up in the pipe that is toxic to breathe in. When you dislodge the clog, the gases will erupt out of the top of the pipe. You also do not want to put downward pressure on the plumbing vent. This can affect the connection to the sewer system and cause bigger, more expensive issues.

Option 1: Remove debris and leaves

Get up on the roof and check to see if leaves or branches are blocking the top of the plumbing vent pipe. If you don’t see something covering the opening, peer into the pipe and see if there is an obstruction. You may be able to pull out a clump of leaves or a stick that is towards the top of the pipe. Tongs will help reach clumps that are several inches down.

Once you have cleared off any debris, check the roof for possible nests. Birds and squirrels will create nests anywhere. If you see one on your roof, remove it immediately. This will prevent the pests from coming up on your roof and lower the chance of them making a nest over your plumbing vent pipe.

Option 2: Using a pole

Most plumbing vent pipes are straight. If an obstruction is too far down to easily pull or pinch out, use a metal pole. Make sure the pole is narrow enough to fit into the pipe. Slowly descend into the pipe. Once you meet resistance, push gently to try to break up the clog. Anything you push down will move through the sewer system.

Do not apply too much pressure. If the clog won’t budge after several nudges, it is too packed in for the pole to be effective.

Option 3: Use a hose pipe with water

Using water flow can dislodge clogs from your plumbing vent pipe. Use a hose that fits into the pipe and slowly snake it down. Turn the water on so it flows down the plumbing vent pipe. Combining a steady flow of water with gentle prods from a metal pole can help break apart dense clogs. The pole can help break up clumps while the water will help flush it down to the sewer. 

Option 4: Use an auger or snake

You can use a regular drain snake or auger to remove clogs in your plumbing vent. Carefully push it down the vent pipe until you meet resistance. Twist or rotate the snake to catch up the clog in the ridges of the snake. Pull the snake out and remove the debris from its sides before putting it back in the pipe. This will take several attempts before the entire clog will be successfully broken apart.

How Do I Keep My Plumbing Vent From Getting Clogged?

The easiest way to prevent your plumbing vent from getting clogged is to keep the pipe free of debris. You can partially cover part of the pipe. This will stop leaves, dirt, and animals from going down the plumbing vent but still allow the gasses to be expelled. 

Inspecting your roof regularly will help you spot issues early and rectify them before a clog occurs. Cutting back tree branches that extend over your roof will also help keep your roof clean.

Keep debris clear.

Dirt, leaves, and small tree branches can fall down the plumbing vent pipe and cause it to be clogged. Branches can also fall and cover the pipe opening, blocking off clear airflow. 

You can use a leaf blower to get the majority of the debris off your roof. Trim back any trees that extend over your roof. This will stop leaves from falling directly onto your roof and plumbing vent. It will also discourage animals from climbing up trees and settling on your roof. 

Regular inspections of your roof are important for maintenance.

Keep out vermin.

Squirrels, mice, and birds will build nests out of the debris. Nests can be built over or around plumbing vent pipes. This leads to clogs. Keep vermin off your roof by removing trees and bushes that are close to your house. 

Snakes can also make their way into plumbing vents. If you experience a lot of issues with vermin on your property, invest in a good plumbing vent cap. This will keep animals out.

Get the right vent cap.

Proper plumbing vent caps fit snugly over the top of the pipe. They are usually made from PVC and should have a variety of holes in the top to allow airflow. These holes should be small and of various shapes to keep out debris and vermin.

Measure your plumbing vent pipe. It is probably 3 or 4 inches in diameter. Purchase one that is designed to fit. It should be difficult to push on, but should not require tools to install. If it slides on easily, it is too large.

Vent caps come in different colors. Purchase one that is the same color as your plumbing vent pipe or roof. This will help it blend in so it isn’t as noticeable when you look up at the roof.

Get the right vent pipe size.

Contractors will usually choose a wider pipe for the plumbing vent. This allows multiple plumbing connections to be able to go through one vent. If your vent pipe is really small, consult a plumber and see if that is contributing to issues with clogging. The average vent pipe is 3 or 4 inches in diameter. This is the perfect size to allow the right amount of airflow.

Keep the top of the vent pipe covered.

Once you put a cover on your vent pipe, leave it on. It should only be removed if it is damaged or if you need to access the vent. Keeping the plumbing vent pipe consistently covered significantly reduces the chances of clogs. 

Only cover your vent pipe with a cover that is designed for plumbing vents. You do not want to restrict too much of the airflow.

When Should I Call a Plumber?

If you have concluded you have a clogged plumbing vent, call a plumber. Plumbing vents are integral parts of your home plumbing system. Causing damage to the vent will result in expensive repairs. Plumbers also know how to expel clogs safely, without exposing the home to toxic gases.

If you want to try to remove the clog yourself, start by inspecting and clearing off the roof. If gentle prodding with a pole or several twists of an auger doesn’t break up the clog, call a plumber. The issue is bigger than the average homeowner can handle.

Plumbing vents are important components of home plumbing systems. Plumbing vents regulate pressure within your pipes to keep water flowing efficiently. They also keep toxic gases trapped in your pipes. Clogged plumbing vents are usually caused by outside factors. Protect the vent pipe from debris and vermin by purchasing plumbing vent pipe covers. 

If you suspect there is an issue with your plumbing vent, call a plumber immediately.

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