[imgur.com]. That link is my basement plumbing. We recently moved in and I noticed the floor was wet below my washer trap. I discovered whenever I flushed from the upstairs bathroom, the washer trap would over flow and then the water would go down. I had the borough come out and they verified my clean out to the street is clear and flowing. Before I call a plumber I'd like some advice. I'm going to try a main line cleaner and see what happens.

that is a pretty poor design you have there.
if it were me, i would cut the 2 inch pipe to the right and cap it. then i would cut in a few 3 x 2 'y's on the left side and move the pipes coming in from the right to the left side. washer hookup as well.
move everything to the right side.
CORRECTION.. MEANT TO SAY MOVE FROM RIGHT SIDE TO LEFT SIDE..



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That 4" cross fitting at the wall is a big part of the problem, the standpipe out of the washing machine drain trap is too short also. It is going to take a bit of repiping to get you system in proper working order.

Thanks for your replies.



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