My Toilet Gurgles When I Run the Shower. Should I Worry?

What the Gurgle Actually Is

Your drain system needs air to work. As water flows down a pipe it pushes air ahead of it and pulls air behind it, and vent pipes running up through the roof supply that air. When everything is working, water leaves quietly and the water sitting in each fixture trap stays put, sealing sewer gas out of your home.

When a drain line is partially blocked or a vent is obstructed, the system starts borrowing air from wherever it can. The nearest available source is often the water in your toilet trap, and air forcing its way through that water is the gurgle you hear. The sound is the system telling you it cannot breathe properly.

The Two Likely Causes

A partial blockage in the shared drain or mainline is the most common. Water from the shower cannot get past the obstruction fast enough, so it backs up slightly and displaces air through the toilet. This is the same condition that produces a full backup later, just earlier in its progression. In older Riverside County neighborhoods with clay sewer laterals, root intrusion is the usual underlying cause.

A blocked vent stack is the other possibility. Vents terminate on the roof and can be obstructed by leaves, nests, or debris. With the vent blocked, the drain system pulls air from the traps instead, which produces gurgling and can also let sewer odors into the house as trap seals get siphoned away.

The distinction matters because the fixes are different, and a camera inspection or a look at the vent settles which one you have.

Why Not to Wait

Gurgling is a partial obstruction. Partial obstructions become complete obstructions, and the difference between the two is the difference between a drain clearing and wastewater on your bathroom floor. Almost every homeowner dealing with a full sewer backup can, in hindsight, remember weeks of gurgling first.

Catching it at the gurgle stage means clearing a line rather than clearing a line plus cleaning up contamination. It is one of the cheapest calls you will ever make relative to what it prevents.

Narrow It Down

• Note which fixture gurgles and which fixture you are running when it happens
• Check whether more than one fixture is slow or gurgling
• Listen for gurgling when the washing machine drains, which discharges a large volume quickly
• Check for sewer odors indoors, which suggests a venting problem
• Look for standing water in the shower or tub after use
• Note whether it is getting more frequent, which means the obstruction is growing

Call a Plumber If

• More than one fixture gurgles or drains slowly
• You smell sewer gas anywhere in the house
• Water backs up into a tub or shower when another fixture drains
• The gurgling is becoming more frequent or louder
• A previous clearing fixed it and it has come back

Related Services

Sewer & Mainline Repair  •  Backed Up Drain Clearing  •  Plumbing Inspection