Hi. For the past couple of months, we've noticed that when we flush the toilet upstairs, water bubbles up in the toilet in the basement. In fact, it is so explosive sometimes that water hits the closed lid. The home was built in the 60s and the basement toilet was added in the 70s. This problem is, however, new. Could it have anything to do with getting a new roof put on in the spring? Thanks for the info.
Pam

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Originally Posted by P123am

Hi. For the past couple of months, we've noticed that when we flush the toilet upstairs, water bubbles up in the toilet in the basement. In fact, it is so explosive sometimes that water hits the closed lid. The home was built in the 60s and the basement toilet was added in the 70s. This problem is, however, new. Could it have anything to do with getting a new roof put on in the spring? Thanks for the info.
Pam

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Hi Pam,
You asked, " Could it have anything to do with getting a new roof put on in the spring?"
Not unless the roof crew let a load of trash and debris fall down in the roof vents.
Are you on a septic tank or city sewer? Your answer will affect mine.

In the meantime let me take some of the mystery out of your "explosive potty".
Let's get clear on the different causes of "bubbling" and "gurgling". Bubbling occurs when you have a blockage or a partial one and the discharge hits it and bounces back sending a bubble of air ahead of it. This bubble can back up the line come belching sewer gas out of your toilet or a fixture trap, (this is where the bad smell comes from). In short, the bubble is caused by pressure.
A "gurgle" is caused by suction and makes itself known by noise in a fixture trap. "Gurgles" are caused by a blocked vent. When you flush or discharge a fixture the draining water sets up a vacuum in the system that's relieved by the roof vents. When a vent's block the system attempts to relieve the vacuum by pulling air through the nearest fixture trap. Hence the "gurgle". The danger here is not a backup but the vacuum could pull the water out of a trap allowing sewer gas to enter your house. Sewer gas is hazardous to your health and the methane content is explosive. Now don't panic! The only reason I explained all this was to take the mystery out of all this. Plumbers should take the time to explain these things and too many don't.

Get back to me and I'll answer ASAP. Cheers, Tom

We've never smelled anything bad. We are connected to the city sewer.

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Originally Posted by P123am

We've never smelled anything bad. We are connected to the city sewer.

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Hi Pam.
I asked to make sure you didn't have a septic tank that neded to be pumped.
You have a partial blockage downstream from the downstairs toilet.
When you flush the upstairs toilet the discharge picks up speed on the drop to the basement sewer, hits the blockage and bounces back with force and then drains away. If you have a basement cleanout remove the cleanout cover and flush the upstairs toilet. If the basement toilet bubbles and then drains past the cleanout then the toilet must be pulled and the branch snaked out, but if the water backs up out of the open cleanout then the clog is between the cleanout and the street and you must snake from the cleanout. Good luck, Tom