Troubleshooting Clogged Drains

Woman looking at pipes under bathroom sink

Here is a list of things that you can do before calling a plumber.

Typical reasons why drains get clogged

1. Clogged drain pipes

Gunk accumulates on the walls of drain pipes and reduces water flow.

Causes: Dirt, skin flakes, hair binding to soap scum


  • Remove and clean the drain stopper.
  • Next, try using a plunger, remembering to block the overflow drain in the tub or sink.
  • If that doesn’t work, remove the drain elbow joint and clean it out.

How to prevent:

  • Clean drain stoppers routinely to prevent clogs and use a hair strainer drain-cover to trap hair before it goes down the drain.

2. Clogged toilets

Flushing items that do not dissolve or break apart in water.

Items: Feminine hygiene products, cotton-tipped swabs, dental floss, pre-moistened diaper wipes


  • Try using a plunger to shoot jets of water to clear the drain pipe.
  • Next, use an inexpensive hand-powered drain auger to reach between 2 to 5 ft. down the toilet’s drain pipe and break up or retrieve whatever is blocking the pipe.

How to prevent:

  • Only flush waste and paper that readily dissolve in water.
  • Clean toilets regularly to keep water flowing smoothly.

3. Clogged kitchen sinks

Leftover food and fat gets caked onto the drain pipe wall.

Causes: Cooking grease or oil, detergent soap scum, un-dissolved food particles such as rice (which expand in water)


  • Run very hot water down the drain to soften the clog, followed by a dollop of dish detergent and then more hot water.
  • Wait a few minutes, then use a plunger and repeat the hot water.
  • If you still have no luck, you may want to use a chemical drain opener, but use caution.

How to prevent:

  • Dispose of large amounts of kitchen grease and oil by letting them solidify. Scrape the mess into a plastic bag, seal it, and throw it out with the garbage.
  • Small amounts of oil (less than one cup) should be thoroughly diluted with hot water and dish detergent before being poured into the sink.
  • For ongoing clogged or slow drains, have a plumber inspect the plumbing to determine if the drain line was properly designed and installed. Both drain pipe venting and slope affect how well drains work.

4. Clogged vent pipe

Sink gurgles when you flush the toilet.

Causes: Not enough air getting into the vent pipe.


  • Check that nothing is blocking the vent pipe opening on your roof, like a bird or animal nest.
  • Check under sinks for gulp valves, typically mounted at the end of a drain line – they look like a plastic cap from a can of spray paint. (The valve prevents sewer gas from escaping the drain line but lets air into the vent pipe when there’s enough suction.)
  • Fill the sink with water and then drain it out all at once. You should hear air getting sucked into the gulp valve. If not, the valve might need to be replaced.


5. Clogged main drain

Slope determines how well wastewater is carried to the sewer line.


  • Too much slope: water can run too fast and leave waste material behind. Over time, the buildup forms a blockage.
  • Too little slope: water and waste pool in the pipe, allowing some waste to settle and form a blockage.


  • Remove any blockages with a plumbers’ snake and then flush out the pipe with water.

How to prevent:

  • Have a plumber install a new pipe set at the proper slope to carry sewage away more effectively.

If your drains are frequently clogged, consider signing up for a drain and plumbing repair protection plan with Enercare. Our plumbing plans come with unlimited service calls and full coverage on parts and labour*.

If your drains are frequently clogged, consider signing up for a drain and plumbing repair protection plan with Enercare.

*Guarantee – Parts and labour guarantees apply to repairs completed to resolve to the original problem identified. Any subsequent problems with your equipment are not covered by these guarantees.