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How to Unclog a Kitchen Double Sink

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A clogged double sink can quickly disrupt your kitchen routine. When water backs up or drains slowly in both basins, it signals a blockage in the shared drainpipe rather than in the individual drains. This makes unclogging a double sink slightly different than addressing a single sink clog. With the right approach, you can clear most double sink clogs without calling a plumber.

What You’ll Need

Gather these tools and materials before you start:

  • Plunger (preferably a flat-bottomed sink plunger)
  • Bucket or large bowl
  • Adjustable wrench
  • Plumber’s snake or drain auger
  • Flashlight
  • Baking soda
  • White vinegar
  • Boiling water
  • Dish soap
  • Old towels or rags
  • Rubber gloves
  • Plastic plug or stopper
  • Cup plunger (optional)

Step-by-Step Unclogging Methods

Step-by-Step Unclogging Methods

Method 1: Plunging Technique for Double Sinks

The key to successfully plunging a double sink is creating proper pressure:

  1. Fill the sink basin you plan to plunge with enough water to cover the plunger’s rubber bell (about 3-4 inches).
  2. Seal the other drain completely using a wet cloth, drain stopper, or rubber plug. This is crucial as it prevents air from escaping through the second drain and ensures pressure is directed at the clog.
  3. Position the plunger completely over the drain opening of the water-filled sink.
  4. Plunge vigorously with quick up and down motions for about 20-30 seconds. Maintain the seal between the plunger and the sink surface.
  5. Check the drainage by removing the plunger. If water drains freely, you’ve cleared the clog.
  6. If unsuccessful, try again with more force or switch to plunging the other drain (remember to seal off the drain you just plunged).
  7. Flush both drains with hot water if the clog clears to remove any remaining debris.

Method 2: Baking Soda and Vinegar Flush

This natural chemical reaction helps dissolve organic clogs:

  1. Bail out standing water from both sink basins using a cup and bucket.
  2. Pour 1 cup of baking soda down the primary clogged drain.
  3. Follow with 1 cup of white vinegar. The mixture will bubble and fizz as it works on the clog.
  4. Seal both drains with stoppers or plugs to keep the reaction focused on the clog.
  5. Wait 30 minutes to allow the mixture to work on breaking down the blockage.
  6. Boil a full kettle of water during this waiting period.
  7. Remove the stoppers and slowly pour the boiling water down the drain to flush away the loosened debris and the baking soda/vinegar mixture.
  8. Test the drainage by running normal tap water into both sinks.

Method 3: P-Trap Cleaning

When clogs persist, the obstruction may be in the P-trap, the curved pipe section under your sink:

  1. Clear out the under-sink cabinet and place a bucket directly under the P-trap to catch water and debris.
  2. Locate the P-trap, which is the curved pipe section connected to both sink drains via a horizontal pipe (often called a “connecting arm” or “waste arm”).
  3. Loosen the slip nuts at both ends of the P-trap using an adjustable wrench, turning counterclockwise. These are typically hand-tightened but may require a wrench if they haven’t been removed in a while.
  4. Remove the P-trap carefully, allowing any trapped water and debris to fall into the bucket.
  5. Inspect and clean the P-trap by removing any visible debris and rinsing it thoroughly with water. A bottle brush can help clean the inside surface.
  6. Check the connecting pipes for clogs by shining a flashlight into them. Remove any visible blockages with a straightened coat hanger or small brush.
  7. Reassemble the P-trap by reconnecting it to the drain pipes and tightening the slip nuts by hand, then giving them a quarter-turn with the wrench. Avoid over-tightening.
  8. Test the drain by running water through both sides of the sink.

Method 4: Drain Snake Method

For stubborn clogs located deeper in the plumbing:

  1. Access the drain either through the sink openings or by removing the P-trap as described above.
  2. Insert the drain snake into the drain or pipe leading to the wall (after P-trap removal). The wall pipe is usually where deeper clogs form.
  3. Feed the snake cable into the pipe by turning the handle clockwise until you feel resistance, which indicates you’ve reached the clog.
  4. Work through the blockage by continuing to crank the snake while applying gentle pressure. You’ll either break up the clog or hook onto it.
  5. Slowly pull the snake back out, which may bring the clog material with it. Have your bucket ready to catch debris.
  6. Flush the drain thoroughly with hot water once the snake is removed.
  7. Reassemble the P-trap if you removed it.

Common Causes of Double Sink Clogs

Causes of Double Sink Clogs

Understanding what typically causes clogs can help prevent future issues:

Food Debris

Small food particles can accumulate over time, especially if you don’t have a garbage disposal or if you put the wrong foods down the disposal.

Grease and Fat Buildup

Cooking oils and fats that are poured down the drain solidify in the pipes, catching other debris and creating stubborn blockages.

Foreign Objects

Items accidentally dropped in the drain like bottle caps, utensils, or jewelry can create obstruction points where other debris collects.

Soap Scum

The chemical reaction between soap and minerals in hard water creates a sticky residue that narrows pipes over time.

Hair and Debris

Hair combined with soap and other materials creates tough clogs, particularly in households where the kitchen sink is used for personal grooming.

Preventative Maintenance

Keep your double sink flowing freely with these preventative measures:

Daily Habits

  • Run cold water before, during, and after using the garbage disposal
  • Use sink strainers to catch food particles and empty them into the trash
  • Avoid pouring grease down either drain – collect it in a container and dispose in trash

Weekly Maintenance

  • Pour boiling water down both drains to help dissolve developing grease buildup
  • Run vinegar ice cubes through the garbage disposal to clean the blades
  • Flush drains with a baking soda and vinegar treatment followed by hot water

Monthly Care

  • Clean the P-trap if you notice drains slowing down
  • Use enzymatic drain cleaners that contain helpful bacteria to digest organic matter
  • Check and clean sink stoppers and strainers thoroughly

Conclusion

A clogged double sink doesn’t have to mean an emergency call to the plumber. With the right tools and techniques, most double sink clogs can be resolved quickly at home. The key difference when dealing with double sinks is remembering to seal off the second drain when applying pressure methods like plunging.

Start with the simplest methods like plunging or the baking soda and vinegar treatment before moving on to more involved techniques like removing the P-trap or using a drain snake. Regular preventative maintenance is ultimately the best way to avoid clogs altogether, keeping your kitchen functioning smoothly day after day.

Jennifer Glover
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