How to Clear Debris from Your Plumbing Vents

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Hose spraying water from 4 different sides to clear debris from plumbing vents.

The black plumbing pipes that stick up out of your roof are parts of the plumbing vent system. They can be made of cast iron, copper or plastic, depending on local code requirements. A plumbing vent is where you may need to look when a sink isn’t draining properly and the drain isn’t clogged.

Since vent pipes are usually only about 4-inches in diameter, blockages don’t happen often. It’s more common to find poorly installed plumbing vent stacks in new-construction homes where the vent stacks don’t extend through the roof.

A clogged vent could show up in your home as anything from toilet “ghost flushes” to sinks that just won’t drain properly. Liquid poured from a can won’t flow evenly unless there is a second opening for air. The same principle applies to plumbing. Air is needed to equalize the pressure in the drain line as water goes down the drain.

That’s the purpose of a venting system so, if the drain lines aren’t vented properly, water rushing down the drains will pull water from nearby P-traps. Your toilet’s drain is basically a P-trap, which is the plumbing fixture installed under the sinks in bathrooms and kitchens. It traps debris that drains from a sink and prevents it from forming a clog deep within the plumbing system. It also stops sewer gases from getting into the house.

When plumbing vents get blocked, air can’t get into the drains and the vacuum produced by rushing water can slow it down or stop it altogether. Worse, the vacuum can allow sewer gases into your home.

Problems that have just recently started, means that there is probably a blocked drain or vent that needs to be cleaned out. If the water in the toilet is dropping and gurgling, the problem is likely near that area.

Causes of Blocked Vent Lines

Things that can collect in a vent line and clog it include the following:

  • Nesting or dead birds
  • Dead rodents
  • Leaves, trash and other garbage (sometimes almost impossible to remove)
  • Tennis balls and baseballs

Preventing Blockages

Clearing vent pipe blockages can be a real hassle but there are some preventive steps you can take to avoid them. An open cover or screen on the end of the vent pipe will prevent debris or nesting birds from causing a blockage and cleaning the plumbing vents should be a routine maintenance task.

 

Fixing a Blockage

The best place to clear a vent pipe blockage is from the roof, which can make it a dangerous job. You may want to have this job done by a plumbing professional but, if you feel confident that you can do the work yourself, follow these tips:

  • Make sure the roof is dry
  • Wear rubber-soled shoes
  • Use a safety harness to prevent yourself from falling if you slip

You’ll need a bright flashlight to shine down the vent pipe to look for leaves, nesting materials or other debris that you might be able to reach and remove from above. Remove anything that you can reach.

Run a plumber’s snake down the vent pipe for items that can’t be removed from above. Put the end of a garden hose down the vent pipe and have someone on the ground turn the water on. Then listen for water backing up and a sudden whoosh when the weight of the water forces the clog into and down the drain.

You could also use the hose the same way you would a plumber’s snake to dislodge a blockage that’s not solid enough to dam water.

Fixing Frozen Vents

For homes located in very cold climates, blockages caused by frozen plumbing vents can be a problem. The best way to clear frozen vents is to pour really hot water into the vent pipe. A simple way to do this is to connect a rubber hose rated for hot water use to the hot water spigot of your washing machine and flush the plumbing vent as previously mentioned.

Have a clogged vent or drain in your kitchen or bathroom? Call WaterWorks Plumbing & Drains now at (416) 489-0000 to have our reliable and qualified team quickly and efficiently repair the vent or drain so you can get back to your routine with the least disruption possible.