Why does the toilet in the basement start bubbling when the upstairs washing machine is on?
April 29th, 2013 | 
Author: It bubbles and it smells like sewage! Do I have some kind of blockage? The sewage smell can’t be healthy. The toilet is close to the main drain in the basement.
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It’s not vented right….could be plugged or it just wasn’t designed right. You are right…it is not healthy…you should get it checked. It might need an air gap vent.
Yes, you have a blockage in your sewer line after it passes the basement toilet. The basement toilet is acting as a vent.
The first thing I would do is put about a gallon of drain cleaner in the basement toilet. Do it at bed time so it will have time to work.
If that doesn’t fix it I would take up the basement toilet and rent a drain snake and use that to clear the drain.
Good Luck.
It’s probably due to a problem with the vent in the sanitary line. Odds are the system was not originally designed for a toilet hooked to that part of the system and the washer pushes a lot of water into the system at once requiring a lot of ventilation for the drain to work properly and it is getting the extra vent from the toilet. Older houses use a common drain/vent and it will get a lining of grease,etc, inside the line and reduce the vent size.
Mine does that too. I asked a plumber about it.
sounds like a vent problem to me. you may need to add a vent for the toilet or the washer. you should call a plumber to check it out and give advice.
If you are on a septic tank system have your tank cleaned or pumped out, and the lines to the tank flushed, Sounds like you do have a blockage
Definite symptom of a main line blockage. Basement toilet is lowest fixture most likely which is why its the one making gurgles/bubbles. I would get it snaked out asap, before you end up having it not just gurgle but come out the toilet altogther. Hopefully you have a cleanout installed so they will have easy access to the line…
You have a bad anti-siphon valve call the plumber