The washer and tub are in the upstairs bathroom. When washer drains the water is coming up into the tub. The tub is also drains slow toilet and sink in bathroom drain fine. Have ran a snake through. What cause be causing the washer to drain into the tub like it does?

Can't say for sure exactly what's causing it, but you've done the right thing by snaking it already. Do you know if it's an older drum trap on the tub? Is the tub plumbing accessible? Usually it isn't...


Anyhow, code typically only requires 1.5" drains for tubs and tub/shower combos, and a clothes washer really needs a 2" drain. It sounds as though maybe the standpipe for the washer is just connected to the tub's drain arm... not really the best thing.

Depending on where the main stack for the house is (often they are fairly close to a toilet), it might not be too hard to add a 2" dedicated drain for the washer, which would be the best.

~aaron


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It was doing OK and then it just started it one day the washer is across the room from tub and toilet is right beside. The tub draines have resntly been replaced from leaking but is still doing so. Tub drained fine after snaking until washer was used again.