How to Unclog a Vent Pipe

How to Unclog a Vent Pipe

When a drain doesn’t clear easily, your first thought is likely that there is something clogging the drain pipe. Could it be food? Hair? Or, worse, a kitchen utensil, bath toy, or other object that should never have gone down the drain?

There’s another piece of your plumbing system that could be to blame: a clogged vent pipe. Vent pipes allow air into the plumbing line, to balance the pressure in the pipe as water goes down the drain. The vent pipe can also be blocked, and when this is the problem, your plumbing system will not function as it should.

Clogged Vent Pipe Symptoms

Signs of a clogged vent pipe are like the symptoms of a blocked drain, but what are the clues? Find out how to tell if a plumbing vent is clogged by evaluating these issues:

  • Bubbling and gurgling:  Does this occur as the water flows down the drain? Does the toilet gurgle after it has been flushed? This can be a sign that air that should be flowing out of the vent pipe is entering the drain and the bathroom vent pipe clogged.
  • Slow Drains:  If one drain in your house is slow, it may make sense to assume that it is blocked. (It’s also possible that the main sewer line is blocked, and if you suspect that this is the case, you should call Benjamin Franklin Plumbing Cedar Rapids for assistance.) However, if every drain in your house is slow, it’s possible this is being caused by blocked vent pipes.
  • The Odor of Sewage: if the air from the drain or toilet smells like sewage, this can also be a sign that the vent pipe is blocked.  A vacuum is being created that is pulling things in the wrong direction.

How to Unclog a Toilet Vent Pipe

In most cases, the vent pipe exits through the roof. Look for a black pipe that is about three inches in diameter, made of cast iron or PVC.

You will need a ladder to access the roof. Be certain to observe all aspects of ladder safety, ensuring that it is placed on solid, level ground, that it has been fully opened and locked, that you do not step above warning labels on the ladder, etc. Have another person with you to assist. If the roof is wet from rain, save the chore for another day for your own safety. Many people prefer to call a professional plumber in Cedar Rapids to perform this task, as working on the roof of a home is dangerous.

Bring these tools with you:

  • Screwdriver
  • Flashlight
  • Garden hose
  • Plumber’s auger (“snake”)

To confirm you have identified the toilet vent, have someone flush the toilet and listen for the draining sound in the pipe.

If there is a cap on the vent, use the screwdriver to remove it.  It’s possible you may see the pipe opening clogged with debris of some sort, such as leaves. Removing the debris could solve your problem.

If you don’t see any debris up top, spray into the pipe with the hose nozzle set to “full” or “jet.” This should clear the pipe, but water begins to come expel from the pipe, you will have more to do. It’s possible, for example, that a bird or other animal crawled into the pipe and died.

If the pipe won’t drain, you’ll need to try the auger. (A 10 to 20-foot length is recommended). Feed the cable bit by bit until you hit a barrier. Turn the handle to push the head through the blockage. Water will begin to drain when you have succeeded. Withdraw the cable (debris often comes with it). Spray more water into the vent to make sure it is no longer blocked.

If these steps do not resolve your problem, contact Benjamin Franklin Plumbing Cedar Rapids for an expert diagnosis and an estimate for the work that will be needed to restore your system, so it is functioning as it should.