When Drain Clearing Fails: Are Your Vents Causing Your Slow Drains?

Few things are as frustrating as a slow draining toilet that takes three or four flushes to clear what used to take just one. If you're tired of wasting water in the bathroom or find your kitchen sink filling up as you wash dishes, your first call is likely to request drain clearing from local plumbers in the area. Consider another common cause of slow drains first and rule out potential vent issues too.

Common Symptoms

Some of the symptoms of a blocked or undersized air vent are similar to the issues caused by clogged drain pipes. These shared signs include:

  • Bubbles rising in standing water like the toilet bowl.
  • Gurgling or percolating sounds when using the drains.
  • Unpleasant odors wafting up and out of the openings, including dangerous sewer gas.

When these are the first signs that indicate a plumbing problem, it's tricky to decide if you need a vent inspection or an auger visit. Do a little investigating on your own to eliminate the possibility of a clog before you call the plumber.

Ruling Out Clogs

Clogs of hair, cooking fats, and food debris develop in both individual and main drain pipes alike. Vent issues don't cause backups that flush sewage back up into the bathtub or toilet, but this is an advanced sign of clogging that doesn't show up right away. Look for early indicators of clogs first, such as:

  • Multiple drains spread across the house all struggling to take in water, since it's rare for more than one or two appliances to share a vent.
  • Water rising out of the drains in a tub or sink when you flush the toilet.
  • Leaks in and around the sewage clean out port.

If you're experiencing slow draining everywhere in the home and have occasional backup problems, it's most likely a big clog in the main line rather than an isolated vent problem. Mixed signals warrant an immediate visit from a plumber to determine which part of the plumbing system needs service.

Checking the Vents

When you suspect clogged or damaged vents are the culprit, you can take a few extra steps to test them yourself before calling a professional. Remove the P-trap below a slow draining sink to see if it drains faster when open, a sign of improper air pressure in the vent. For toilets and tubs with less accessible P-traps, try getting up on the roof and flushing water down the vent outlet. Standing water in the pipe means a blockage is interfering with air flow too.

In some cases, slow drains and gurgling toilets come from an inadequate number of vents instead of clogs or collapsed pipes. Vents can also disconnect from the rest of the plumbing after years of use and let sewage gas escape into the home. Get your plumbing vents inspected every three to five years to catch problems that aren't causing any obvious signs yet.

Professional Solutions

Unless you're dealing with a bird's nest built right into the top of a vent pipe, you need a plumber to handle the actual cleaning and repair work. The professional may need to open up the walls and floors to get at particularly damaged sections of pipe. However, it's important to invest in the work even if it means doing some remodeling because letting a sewage vent leak threatens your health in the long run.

No amount of drain cleaner or snaking fixes a slow drain when it's an air pressure problem instead. Before you spend hundreds of dollars on multiple visits for what you think is a clog, make sure your vents are in good shape. Something as simple as a chunk of ice or a broken tree branch could affect how your toilet and washing machine work.