Question for Any Plumbers on Here

My new house has two toilets that run into a common pipe and then into my septic tank. When one is flushed, the other bubbles up. Is that normal? If not, is it something I need to worry about?

Sounds like a venting problem.

That definitely shouldn't happen, but I don't know why it's happening to you or if it's a problem. Yes, you are welcome. Phone Post 3.0

Both bubble when the other is flushed. I don't think the septic tank could be full. My neighbor told me the previous owner had it drained just a couple of years ago. I was thinking maybe it was a blockage. But I'll check the vent tomorrow.

Drink a few beers and sleep it off. If problem continues, repeat. Phone Post 3.0

Ridgeback -

If you can get on your roof try to find the venting pipe and see if you can see obstructions with a flashlight or run a snake down it as far as it will go.  You could also pour some drain cleaner down the vent and see if that does anything.  

Septics can fill up if a lot of unbreakable downable stuff was flushed into it like paper towels and wet wipes.  Definitely check that out as well. 

Unbreakable downable made me laugh. Its rare for you to not know how to say something. It made me happy. Phone Post 3.0