Downstairs Toilet Bubbles When Upstairs Toilet Is Flushed(Causes and Fixes)

Have you ever faced downstairs toilet bubbles when the upstairs toilet is flushed? You might be wondering what is the reason behind this issue.

Toilet bubbles usually appear in multiple toilets due to a clogged main line. Besides that, the issue could also be due to poor drainage systems and blockage in sewer lines.

Apart from that, it also depends on a few other factors such as:

  • The setup of drainage piping
  • The pressure of the water supply
  • The amount of water used during flushing

In this article, we will take a look at the problem i.e., downstairs toilet bubbles when the upstairs toilet is flushed, and some of its possible causes. So if you are interested in learning all this, keep on reading!

Why Do Toilet Bubbles Appear Downstairs When Upstairs Toilet is Flushed?

The main reason for toilet bubbles downstairs is due to clogged mainline. In most houses, the main drain line is responsible for carrying all the wastewater from different toilets to the sewer or septic tank.

Now, if this main drain line gets clogged, it will result in a backup of wastewater. This backup of wastewater will push its way through the weakened spots or cracks in the drain line and will eventually come out as bubbles in the toilet downstairs.

Apart from that, toilet bubbles can also be caused by a few other factors, such as:

Poor Drainage System:

man fixing a clogged pipe
Image from California Pool Association

A poor drainage system can lead to toilet bubbles if your house has a poor drainage system. This is because the water will not be able to drain properly and will start accumulating in the low-lying areas. As a result, the pressure will build up and eventually push its way through the cracks and weak spots, leading to toilet bubbles.

Blockage In Sewer Lines:

Another possible reason for toilet bubbles can be a blockage in the sewer lines. If the sewer lines get blocked, it will cause a backup of wastewater. This backup will then push its way through the cracks and weak spots in the drain line, leading to toilet bubbles in the downstairs toilet.

The Setup Of Drainage Piping:

The way your drainage piping is set up can also affect the formation of toilet bubbles. If the piping is not installed properly, it can create pockets of air that will eventually lead to toilet bubbles.

main water supply valve
Image from Central York Corporation

The Pressure Of Water Supply:

The pressure of the water supply can also be a factor in the formation of toilet bubbles. If the water pressure is too high, it can cause the water to push its way through the cracks and weak spots in the drain line, leading to toilet bubbles.

The amount of water used during flushing: The amount of water used during flushing can also affect the formation of toilet bubbles.

If you use too much water during flushing, it can cause the water to push its way through the cracks and weak spots in the drain line, leading to toilet bubbles.

How to Fix Toilet Bubbles?

If you are facing the issue of toilet bubbles, there are a few things that you can do in order to fix it. Some of the things that you can do are:

checking the main drain line
Image from Plumbing services and repairs

Check The Main Drain Line:

The first thing that you need to do is check the main drain line. If you think that the main drain line is clogged, you can try to clear it yourself, or you can call a professional to do it for you.

However, I don’t recommend checking the main drain line yourself unless you are an expert in this. It is because the main drain line is always risky and can be messy. Therefore, it is highly recommended to call a professional plumber.

Check The Sewer Lines:

Another thing that you can do is check the sewer lines. This will be easier if you have an open pipe fitting in your house. However, those who have closed pipes may face some trouble.

The best way to check the sewer lines is by using a drain camera. This is because a drain camera can help you see inside the pipe and locate the blockage easily.

If you don’t have a drain camera, you can try to use a plunger or a snake to clear the blockage. However, these methods are not as effective as a drain camera and can be messy.

Check The Water Pressure:

If you think the issue is with the water pressure, you can try adjusting the pressure regulator. However, I highly recommend you call a professional plumber for this as it can be risky.

water pressure reducing valve
Image from Water feel solution

Regulators can also be tricky and sometimes can cause huge trouble if not handled properly. You can easily break it if you apply a little bit of force, and thus, you will need to change it. 

Increase The Amount Of Water Used During Flushing:

If you think that the amount of water used during flushing is too low, you can try to increase it. This will help in increasing the water pressure and will also help in clearing any blockages in the drain line.

Conclusion

To conclude, toilet bubbles can be caused by various factors such as a clogged main drain line, a blockage in the sewer lines, the setup of drainage piping, the pressure of water supply, and the amount of water used during flushing.

There are a few things that you can do in order to fix toilet bubbles, such as checking the main drain line, the sewer lines, and the water pressure. You can also try to increase the amount of water used during flushing.

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