Hello and Help! The water from our washing machine is routed into our sump pump pit which then ejects that water to the main pipeline. For years, every time we wash clothes and the pump starts ejecting the water, the toilet gurgles several times and almost all of the water gets sucked out of the bowl. Rarely, water would also simultaneously back up into the bathtub. We think the previous owners had what appears to be some kind of check valve installed in the pipe that connects the pump to the main line. Anyway, there have been one or 2 occasions where if someone just happened to flush the toilet at the exact same time the pump started running, it would flush but come right back up into the bathtub. Downstairs in the basement, water would be leaking from the pipe that comes out of the bottom of the toilet at the same time and spraying all over the basement floor. All this came to a head this past Father's Day weekend when everything seemed to be backed up and we couldn't shower because the water wasn't draining at all, and we could flush the toilet but it would just go straight to the bathtub. We had our main line snaked with a huge auger and there were no blockages until it reached the street. Once that was cleared, we didn't seem to have any issues. We washed clothes and watched the water in the toilet - it would move as though there was still some suction going on, but it would never gurgle. Well, after a few days, we were back to the gurgling every time we washed clothes. This morning we happened to flush the toilet right as the pump started running and same thing as before - it all backed up into the bathtub and you could hear a loud "swishing" in the pipes under the bathroom like the water was trying desperately to find somewhere to go. So, I say all of that to say this. Everyone we talked to said that these issues were likely due to a blockage in our main line. Well, we just had our line snaked and cleared out, so that's obviously not the issue. Thoughts? Suggestions? Opinions? I welcome anything because we are ready to pull our hair out. THANKS!