Why Is My Sink Making a Gurgling Sound?

Draining water from one appliance can cause gurgling in drains attached to the same line.

The gurgle heard in a drain pipe is the sound of air bubbles coming from the main drain and escaping out of the nearest hole. The process occurs when water from a sink, tub or other drain traps air in the piping. Vent pipes that extend to the roof typically prevent this from happening, but various obstructions and issues with the pipes can lead the gurgling sound.

Slow and Blocked Drains

A kitchen sink sees a lot of grease and food particles go down the drain. The particles, especially grease, adhere to the sink and main drains, over time reducing the ability of water to flow smoothly through the pipes. A buildup of gunk on the walls of the pipe causes a slow drain. A sink will gurgle when another drain on the line is attempting to flow but is blocked by a buildup of gunk in the pipe. Air cannot flow around the water in the pipe so instead bubbles up through the pipe, releasing a gurgling sound from the nearest open hole -- typically a sink or tub. The same holds true if the pipe is blocked by a large deposit of organic material such as toilet paper. The gurgling occurs when the blockage is at or before the vent pipe.

Blocked Vent Pipe

Vent pipes exit through the roof of the house. The vent pipe is a vertical pipe connected to the main drain that allows the flow of air in the pipe, preventing a vacuum from occurring. Water flowing through the pipe forces air out of the vent pipe. A bird's nest, leaves or accumulated dirt can settle into a vent pipe on the roof, blocking the flow of air. Air that cannot be forced out of the vent pipe pushes back into the drain pipe, causing bubbles. The bubbles seek out the nearest opening, causing gurgling sounds to emit from the sink.

Repairing Blockages and Slow Drains

One of the best ways to prevent a blockage or slow drain is not to flush or pour anything down the drain that can cause a buildup to occur. Grease, large chunks of food and hair should be kept out of drains. In the event that a buildup occurs, chemical drain openers, available from any hardware store, can be poured into the drain to clean the walls of the pipe. The chemicals are caustic, so follow the directions on the bottle carefully to avoid personal injury. Large blockages that cause slow drains and gurgling pipes throughout the house indicate a larger blockage in the main pipe. Contact a plumber to have the main drain snaked with a plumber's snake.

Vent Pipe Repair

Vent pipes are not as easily cleaned as a main drain. The piping is as tall as the house, and blockages are not as readily seen. Shining a flashlight into the vent pipe from the roof can reveal a bird's nest or animal in the pipe but does not always show to the lowest point of the vent. Contact a plumber to have the pipe inspected and cleaned. Vent pipes should have a cap installed, which can be accomplished with basic tools. Pipe caps are available from any hardware store and block animals and leaves from falling into the pipe.

References

• "Lowe's: Complete Home Improvement and Repair"; Don Vandervort; 2005