My Toilet Bubbles & Gurgles When Washer Drains – 5 Causes

Written by

Paulk Webb


Freddie J. Hagopian

Saveourwaterrebates is reader-supported. When you buy via our links, we may earn a commission at no cost to you. Learn more

my toilet bubbles & gurgles when washer drains

Why do my toilet bubbles & gurgles when washer drains? The answer is pretty simple: normal airflow is disrupted within the pipes causing negative pressure or backflow.

However, the cause of this obstructed flow varies. Several problems occurring within the pipes of the toilet and washer may be the root cause of the bubbles and gurgles.

Read on to know why, of all places, draining the washing machine affects the toilet, specifically. Also provided are some quick fixes and a little background on how the drain system works.

Why Does My Toilet Bubble & Gurgle When the Washer Drains?

So your toilet gurgles when washer drains – “what causes this?” you ask. Here are a few common reasons why your toilet has such an issue:

Reason #1: They have connecting drains or they share the same vent stack


Two possible reasons for a toilet bubbling when washer drains are that they are connected to the same horizontal drain going to the soil stack or they share a common wet vent.

In both cases, air pressure enters the drain system as the washer drains. The air will also try to escape through the nearest opening – which is the toilet, in this case. Hence the bubbling and gurgling we see.

It is not uncommon that a washer and toilet share the same drain; hence this problem is a usual sight for homes with the said setup.

Reason #2: Main drain could be partially clogged


Obstructions in the main drain or waste pipe could potentially be the cause of a gurgling toilet. Things like hair, tissue, or other sanitary items can clog the common pipes of the toilet and washer.

Since the drain way is obstructed, water and air is forced to flow backward whenever you drain your washing machine.

Thus, the gurgling and bubbling in the toilet is nothing but the air and water backing up and escaping the clogged pipes.

Clogging can also be confirmed if the toilet drains slowly and gurgles.

Reason #3: Vent Pipe is clogged


Vent pipes maintain air pressure in the drain system by providing ventilation. It is the vertical pipe that sticks out of the roof. Since it has no cover on top, it is vulnerable to clogging as it accumulates dust and debris, even animals that can get stuck within the pipes from its surroundings.

When the vent pipe is blocked, negative air pressure, or suction, can form. This creates a vacuum that, if strong enough, can pull air from any opening. Thus, gurgling and bubbling occur in the toilet.

Ideally, this would not cause problems when the sink drains, even with bathtubs, since they require less pressure.

So, sink gurgles are less probable, unlike toilet and washer drains that need more airflow – making gurgles more common.

Reason #4: Faulty installation of washer’s drain pipes


Pipes for the washing machine drain need to be the correct length and diameter to ensure proper function. Too small or too big of a size can cause problems to the draining system.

As such, if the pipes are poorly installed, air would not reach them, and wastewater flow would be inefficient. The washing machine will be forced to pull air from the toilet to aid it in draining.

Similar to when the vent is clogged, the toilet will act as a suction (due to negative pressure) and pull the surrounding air – consequently leading to bubbling and gurgling once again.

It is recommended to fix this issue as soon as you can. If prolonged, this can lead to a toilet that overflows when the washer drains and would be a new problem for your bathroom.

Reason #5: Blocked sewer line


A blocked sewer line typically manifests itself when not just the toilet, but several other fixtures in your house are already gurgling.

Additionally, a ‘toilet gurgling heavy rain’ occurrence is another notable indication of a blocked sewer line.

Again, air will flow backward when there are blockages in the pipes, causing what others describe as “my toilet is blowing bubbles” as you drain your washer or as it rains heavily.

If the sewer lines are indeed blocked, the problem is already severe and would entail costly repairs. This would typically affect the whole neighborhood, and professionals would be needed.

How to Stop It?

A toilet pipe gurgling when not in use is definitely bothersome. Here are a few quick and easy ways how to fix a gurgling and bubbling toilet:

  1. Plunge your toilet to deal with clogs
  2. Remove clogs by using a drain snake
  3. Seal off the drain and plunge the toilet
  4. Install a 2-inch drain with a P trap in the washer
  5. Clean roof vent stack
  6. Clean main sewer line

How Does the Drainage System Work?


Your home’s drainage is the system of pipes that get rid of wastewater. Ideally, it relies on gravity to pull wastewater out of your house and towards the sewer.

So, vertical and angled pipes flow with ease. It is the horizontal pipes that usually get clogged with grease or any solid waste. These blockages can have a significant impact on the functionality of the entire system.

Alongside these pipes that carry the wastewater itself, the drainage system also employs vents, traps, and cleanouts that ensure safe and efficient flow to the main sewer.

Firstly, vents let air enter the pipes so that wastewater flows out properly. This opening is situated on the roof of your house.

Traps, on the other hand, prevent the backflow of unpleasant gasses from the sewer pipes. These are the curve-shaped devices under the sink or built in the toilet.

Lastly, cleanouts provide access to clean or inspect any blockage within the pipes. They are usually found on the side or in the basement of your house.

This intricate system of pipes carefully laid out underground enables safe and efficient transport of our wastes – like when we flush toilets or when washing machine drains septic or sewers.

All drainage systems employ these principles in maintaining the efficient flow of used water to the sewer plant. And any problem that may occur in these components can affect the whole system.


We answered your question ‘why does my toilet bubbles & gurgles when washer drains?’ with the common reasons and the different remedies that you may do at home.

If all suggested quick fixes fail to show improvements, never hesitate to contact local officials or plumbing professionals. The last thing you would want is to prolong and worsen the issues of your drainage system.

5/5 - (3 votes)