Is your toilet making odd gurgling sounds whenever your washing machine drains? You’re not alone. This common plumbing issue often indicates a clog or ventilation problem in your drainage system. Below, we’ll explore five possible reasons why your toilet gurgles when your washing machine drains – and how to fix it.

Why Your Toilet Gurgles When Your Washing Machine Drains

Below are five reasons why your toilet gurgles when your washing machine drains.

1. Clogged or Partially Blocked Drains

How it works: A clogged drain is one of the most common causes of toilet gurgling. When your washing machine drains and the water flow meets a blockage, air and water are forced back up through connected pipes – often escaping through your toilet.

Signs of a Clog:

• Slow-draining sinks or showers
• Frequent toilet backups
• Gurgling sounds from multiple fixtures

2. Blocked Vent Pipe

Why it happens: Your drain and sewer pipes connect to a vent pipe, usually installed vertically. This vent pipe helps release air and gas from the plumbing system. If it’s blocked by debris (leaves, twigs, or even a bird’s nest), air can’t flow freely, and water movement in the pipes can create gurgling noises in your toilet.

3. Improperly Installed Washing Machine Drain

Why it happens: Washing machine drains need a specific size, length, and diameter to function correctly. If the drain was installed incorrectly, air can’t properly reach the pipes, and pressure imbalances may result in your toilet gurgling whenever the washer is in use.

4. Blocked Sewer Line

Why it happens: If multiple fixtures in your home gurgle or back up simultaneously (toilet, sink, shower, etc.), the main sewer line could be blocked. All your drains connect to this primary sewer line, so any blockage there can force wastewater and air back up through the plumbing system – causing gurgles, bubbling water, and slow draining. Read more about when it’s time to replace your sewer line.

5. Shared Drains Between Toilet and Washing Machine

Why it happens: In some setups, the washing machine drain is connected to the same line as the toilet. If they share a venting system, any restriction or clog in the line can lead to a backflow of air that escapes through the toilet bowl, creating that gurgling noise.

Now that you know the main causes, here are some proven solutions to restore smooth drainage and quiet plumbing.

1. Plunge Your Toilet

How to Do It:

1. Position the plunger so the bell shape completely covers the toilet drain.
2. Gently press down to expel air from the plunger (preventing water from splashing).
3. Use firm, steady pushes for about 20 seconds to loosen any clogs near the surface.
4. Test by running the washing machine again. Repeat if necessary.

If plunging doesn’t solve the issue, you may need to move to more in-depth methods.

1. Place the plunger with the bell shape covering the toilet trap and exert light pressure. This gets all the air out of the plunger without blowing water all over you.
2. Once the air is out, you can start exerting more force, plunging in and out. Plunge the toilet for about 20 seconds. Remember not to break the plungers seal.
3. If you can still hear gurgling when your washer machine drains, keep plunging or move on to the next solution.

2. Clean Your Roof Vent Stack

If your roof vent stack doesn’t have a screen, debris can fall inside and prevent air from escaping. This step involves getting up on your roof with a garden hose. If you don’t feel comfortable doing this, call a professional plumbing company.

1. Use a ladder to climb up on your roof.
2. Locate the pipe sticking out. (This is your vent stack).
3. Use your hand to clear out any twigs or leaves close to the surface.
4. If you don’t see any debris at the top, take the garden hose and begin pouring water down the vent. The water should push any clogs down the drain.
5. If the garden hose doesn’t clear any clogs, try using a sewer snake to pull out any debris.

3. Clean Your Main Sewer Line

Besides using a sewer snake, one of the best pipe cleaning solutions is hydro-jetting. Hydro-jetting uses a self-propelled nozzle that shoots up to 4,000 PSI of water into your sewer pipes. Hydro-jetting uses different nozzles for different types of obstructions, such as tree roots or sludge. The cleaning process is non-invasive because it only requires access to a cleanout or removed toilet.

Hydro-jetting is commonly used by restaurants because it can easily get rid of grease buildup. If you want a powerful, clean, and safe solution, call a professional and ask about hydro-jetting.

Read more about hydro-jetting.

Calling The Professionals

If your toilet gurgles when your washing machine drains, and you can’t seem to find out why, call a professional sewer repair company. If you live in the Greater Los Angeles area, get in touch with New Flow Plumbing. We’ll get you started with a CCTV sewer camera inspection to determine where your problems come from. Then, we give you a free repair estimate, followed by available repair options.