Mainline stoppage.
There is a blockage in your main sewerline.
the plumbing drain vent is not installed or poorly installed.
Toilet bubbles appear when showering because the water pressure from the shower can create a vacuum in the drain pipes, causing air to be sucked in through the toilet's water trap, resulting in bubbles.
Your toilet may gurgle when flushed due to a blockage in the plumbing system, such as a clog in the pipes or a venting issue. This can cause air to be trapped in the pipes, leading to the gurgling sound when the toilet is flushed. It is important to address this issue promptly to prevent further plumbing problems.
Your drain line is plugged somewhere after your shower and toilet line are connected. The reason for the gurgle in your toilet is because air is trapped in the drain and your toilet is the closest place for air to flow to. If you had a vent on your toilet trap arm then it would gurgle in the vent rather in your toilet but your drain is still plugged and needs to be snaked out and maybe your drain line needs to be examined for right grade or broken.
A mainline stoppage.
A toilet gurgles when there is a blockage in the plumbing system, causing air to be trapped and released as water flows through. This can be due to a clog in the pipes, a malfunctioning vent stack, or issues with the toilet itself.
The toilet gurgles when there is a blockage in the plumbing system, causing air to be trapped and released in the pipes. This can happen due to a clog or improper venting, leading to the gurgling sound.
Your toilet gurgles when the washer drains because there is a blockage or restriction in the plumbing system, causing air to be sucked in through the toilet's trap. This can create a gurgling sound as the water drains from the washer.
When your toilet bubbles while you're showering, it could be a sign of a clog or blockage in your plumbing system. The bubbling occurs because the water from the shower is not able to flow smoothly through the pipes, causing air to get trapped and create bubbles in the toilet. It's important to address this issue promptly to prevent further plumbing problems.
Gurgle is a noun (a gurgle) and a verb (to gurgle).