I bought a house recently and since I moved in, I can't get the washing machine drain to stop overflowing. I even installed a "water flow restriction" (which is just a C-clamp on the drain hose. I know this is not ideal, and it was a temporary solution) First I completely tore out the old drain pipe, because it was WAY too short of a standpipe, for code. That didn't help. After the flow restriction it no longer overflowed, and I kinda left it at that. But now it's back to overflowing, almost every single drain cycle that the machine does. It's absolutely maddening. Best as I can tell, I need to relocate the drain higher up on my 3 inch pipe, because what I suspect is happening, is that it's entering the pipe at a 90 degree angle, and is not able to go anywhere past that quickly enough, so it backs up back into the washing machine drain pipe, and out the top. It's either that, or the P-trap cant' handle the amount of water flow. I'm unsure of how much flow my washing machine outputs. It's weird, because my my old apartment, I never had any sort of issue like this with this same washing machine and I've never heard of this being a problem for anyone. Also weird is the my main 4 inch drain is located so high up on the wall, that I'm required to pump the washing machine to nearly the ceiling, especially if I'm going to have to relocate my drain higher on the 3 inch pipe.