Why Does the Floor Drain Gurgle When the Toilet Is Flushed?

Gurgling in a floor drain indicates a problem with the house's plumbing.

Gurgling in your house's plumbing indicates a problem with the plumbing system and should not be ignored, even if the gurgling comes from the floor drain. The air in your house's drain pipes should not be attempting to escape out any drain opening, unless an obstruction in the system causes the gurgling.

Clogs

A clog in any drain line, including a toilet or floor drain's line, will result in symptoms like gurgling when water washes down another drain line. Unclogging floor drains requires a power auger and the expertise and experience of a plumber, and so should be left to professionals. Unclogging a toilet does not require plumbing expertise. Use a plunger on the toilet, sealing the plunger's cup over the drain opening and pumping the handle up and down hard at least a dozen times. If the plunger does not stop the gurgling, run a toilet auger down the toilet's drain as you spin the handle clockwise. Turn the handle counterclockwise as you remove the auger from the drain.

Venting

Before you call a plumber to run a power auger through the floor drain, examine the venting system for the house. Improper venting will lead to air problems in the pipes, since the vent pipes that connect to drain pipes will replace lost air in the drain pipes as well as vent sewer gasses. A clog or damage in the vent pipes will lead to problems with the drain system, until you correct the problem.

Vent Pipe Problems

Examine the vent pipes yourself from the house's rooftop. Remove any bird nests or other debris from the top of the vent pipes, and then shine a flashlight down each of the pipes. Use tools you have on hand to extract any obstructions that sit close to the vent pipe openings. For obstructions that sit farther down the drain, use a drain auger or the garden hose to break them apart and force them down the pipe.

Professional Help

If, after attempting to unclog the toilet and the vent pipes from the roof, you still do not see success, contact a plumber for help. The plumber will not only run a power auger down the floor drain, but he will also examine the vent pipes using artificial smoke. The plumber will locate clogs in the drain pipes or identify areas of damage that affect how the pipes vent.

References

• "This Old House"; Silencing a Gurgling Toilet; Richard Trethewey
• Ask the Builder; Toilet Repair Instructions for 10 Common Problems; Tim Carter