How To Clear a Clogged Plumbing Vent

A clogged plumbing vent can cause a slew of problems, including slow drains, gurgling noises, and unpleasant odors. Luckily, clearing a blocked vent stack is a relatively straightforward task. Below, we’ll walk through how to clear clogged plumbing with help from the This Old House plumbing and heating expert Richard Trethewey. 

What Are Plumbing Vents?

Plumbing vents are vertical pipes that extend from your plumbing system through the roof, allowing air to enter the pipes and facilitate drainage. Without proper venting, various plumbing issues like slow drainage and pressure imbalances can arise.

What Are the Signs of a Clogged Plumbing Vent?

Recognizing the symptoms of a clogged plumbing vent is the first step in addressing the issue. Common signs of a clogged vent include the following:

• Foul odors emanating from drains
• Gurgling noises from drains or toilets
• Slow-draining sinks, showers, or toilets
• Water backing up in sinks or tubs

What Causes Vent Blockages?

Several environmental factors can create a clogged plumbing vent. Here are some common causes:

• Bird or small animal nests obstructing the vent
• Damage to the vent pipe
• Ice formation in colder climates
• Leaves and debris accumulating in the vent opening

Tools and Materials Needed To Clear a Clogged Plumbing Vent

Before attempting to clear a clogged plumbing vent, gather the following tools and materials:

• Electrician’s probe
• Garden hose
• Inspection camera (can be rented)
• Ladder
• Safety glasses
• Safety harness (for roof access)
• Work gloves

How To Handle a Plumbing Vent Clog

The first step in clearing a clogged plumbing vent is to pinpoint the location of the obstruction. This process involves careful inspection and testing.

1. Accessing the roof: Safely access your roof using a sturdy ladder. Always prioritize safety when working at heights, and consider using a safety harness for added protection. Make sure the ladder is stable, and if possible, have someone assist you.
2. Using an inspection camera: Once on the roof, locate the vent stack. Slowly feed an inspection camera down the vent pipe, watching the monitor for any signs of obstruction. This tool allows you to visually identify the clog and its location within the pipe. The clarity provided by the inspection camera can help avoid unnecessary guesswork.
3. Flushing test: While the camera is in place, have someone inside the house flush a toilet. If you can’t see water running down the stack from the toilet, you’ve likely located the clog. This test helps confirm the presence and approximate location of the blockage. It’s a practical way to correlate the visual data from the camera with physical symptoms in the plumbing system.

Clearing the Clog

With the clog identified, it’s time to clear the obstruction and restore proper venting to your plumbing system. This stage involves a combination of probing and flushing techniques.

1. Probing the clog: Insert a 12-foot-long electrician’s probe down the vent stack until you reach the clog. This helps determine the nature of the obstruction and may even dislodge some of the blockage. The probe’s length allows you to reach deeper blockages that might not be visible.
2. Inspecting the probe: After probing the clog, remove the electrician’s probe and inspect its end. In most cases, you’ll find a mass of soggy leaves or other debris that provides clues about the nature of the blockage. This inspection helps you confirm the clog type and the clearing method moving forward.
3. Using water pressure: Feed a garden hose into the vent stack, lowering it all the way down to the clog. Turn on the water and use the pressure to flush out the obstruction. Gently move the hose up and down to help break up the clog. Water pressure is particularly effective at loosening debris and flushing it out of the system.
4. Confirming the clear: Once you believe the clog has been cleared, perform another flushing test. Have someone inside flush the toilet while you observe the vent stack. If you see water flowing freely from the toilet down the stack, you’ve successfully cleared the clog.

Preventing Future Clogs of Plumbing Vents

Taking proactive measures can help prevent future vent clogs. Regular maintenance can save you from the inconvenience and cost of severe blockages.

• Regular inspections: Perform visual inspections of your vent stacks at least once a year, particularly after storms or high winds that may have blown debris on your roof. 
• Vent covers: Consider installing vent covers or screens to prevent leaves, animals, and other debris from entering the vent stack while still allowing proper airflow. These covers are an effective way to reduce the risk of obstructions without hindering the vent’s function.
• Professional maintenance: Schedule regular maintenance with a plumber to catch potential issues before they become major problems. A plumber can perform a thorough inspection of your entire plumbing system, including the vent stacks.

When To Call a Professional To Clear a Clogged Plumbing Vent

While many homeowners can successfully clear a clogged plumbing vent, some situations warrant professional assistance. Calling a professional can prevent the possibility of causing additional damage in the following scenarios:

• If you’re uncomfortable working on the roof
• If you suspect damage to the vent pipe
• When dealing with multiple or recurring clogs
• When the clog persists despite your best efforts