Hi There,

Question about washer drainage pipes and possible overflow. If I reduce pvc pipe from 2'' to 1 3\4'' for my washer machine drainage will that create over flow? Reducing will take place on the same pipe were is air vent for drain just 10 feet bellow in the basement. We just installed everything for w\d but because it is older house drain pipe in the basement is rusty so it leaks when we connected pipe to it( see pics) . I Want insert pvc pipe into metal drain to skip using rusty pipe but I am concern about possible overflow cause by reducing the drain pipe size.
Thanks a lot!
Cheers,
Victor,
Washington DC

The restriction in the old pipe could cause a back up depending on how fast your machine drains, 2" is standard. You could remove the short piece of old pipe that goes into the cast drain line and run 2" pvc into it. I'd be more worried about the mold problem you have in your walls.

If reducing the pipe size results in a back up you can install a compression fitting,(see image) or simply close off the connection between the washer hose and washer standpipe. This will force the washer dischgarge past the trap and out into the main. Good luck, Tom

Thanks for reply. I will that and let you know