I’ll try to keep this short and explain as best as I can. I’m a first-time home-buyer, single guy, living in an older home. The previous owner said he replaced the plumbing within the past couple of years. But here’s my dilemma; When I run the washer, my line will randomly back up always on the final drain cycle. When it gets backed up, every time the toilet and bathtub in my bathroom will start to overflow with sewer water, (bad smell, debris). Now, the bathroom and laundry room are on separate ends of the house, and the bathroom and laundry room are apparently on separate lines but both connect to the main line which connects to a city sewer a good long distance from the house. Last year this happened once, where it was completely backed up and I had to call a plumber to snake the main line. But since then, sometimes it will back up, I just wait it out and let everything go down, and everything will go back to completely normal. Sometimes it will back up, and for days, any time I flush the toilet, or use the shower or water, I can hear a “bubbling” sound in the pipes immediately and can’t use too much water or it might back up. And then most of the time everything is completely fine and it just works as it should. I have tried root killer, I have tried a main line cleaner. What is happening and how do I fix it?