How to add a washing machine drain to an existing cleanout in basement

taco_truck_tom

I have the setup shown in the photos below in my basement. I would like to add a proper drain for the washer, i.e., an 18" standpipe with a P-trap that stands at most 18" above the floor. Right now, the cleanout plug is on the right side of the double wye, placed just on top of the main drain. There's no way to add anything below the double wye down the main drain pipe. I'm completely new to plumbing. This is my plan. extend from the wye on the...

Originally asked by loclos on Stack Exchange (diy) (CC BY-SA 4.0).

uphilltech

Great question — answering as the UphillTech team:

Not a plumber but redid my basement washing machine drain last year. Just some things to keep in mind off the top of my head. Remember that it's a good idea to introduce a small slope in horizontal vent runs, so that any condensation can drain happily back into the drain system. Also note that, depending on how high that p-trapped sink is, you might be creating a new low point for sewage to back up into your house if there's ever an issue in the street. It's an unlikely scenario, but when I did mine, I included a PVC backflow preventer valve just in case.

Full answer by JG307: https://diy.stackexchange.com/a/244115 (CC BY-SA 4.0).

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