Can I run three inch and a half lines into one two inch on a 4x4x2 wye
I have a bathroom sink a tub and a kitchen that want to run together into a 4-inch main. So I'm tapping in a 4x4x2 wye and I have a 1-1/2 x 1-1/2x1-1/2x1-1/2 triple wye and a 1-1/2 to 2 reducer. Does that sound ok?

I say no. If all 3 fixtures were to drain at the same time, you would exceed the allowed fixture unit loading for 1 1/2(the outlet size of the wye). Are 1 1/2" drain pipes allowed on your sinks? Some codes require a minimum 2".
"

They are always 1-1/2 here. I'm not a plumber obviously but that's always what I've seen done. what about two 1-1/2 into a 2 inch?
If I have room I could put a 2" wye on the 4x4x2, so two could go into one and one in the other.
But it's really tight under this crawl space.
Also there would almost never be all 3 run at the same time.
It's a tiny house basically for single person or two max but of course theoretically possible.
In reality will never occur.



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use a full size 2 x 2 x 2 x 2 double "Y" and reduce the 3 inlets to 1 1/2.

put a full size 2 inch cleanout tee as well.

Codes are concerned about what COULD happen, NOT "reality".

wont' have room for a cleanout tee between the 4x4x2 and the 2x2x2x2 dbl tee
very tight crawl space
had to dig down a couple feet to fit 4x4x2 with dbl tee on top and still have fall from the 1-1/2 lines
only option would be (3) 1-1/2 cleanouts on ea run before they enter the dbl tee

darn tried to draw a picture but didn't look right on the site
anyway i have quick vents on each fixture and no plumber would ever go down that crawl space to use the cleasnouts
but they can snake from the quick vents can't they?



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yes

Thanks Packy etal,
wow gluing up pvc in an 18" crawlspace with no air circulation sure is fun.
don't think I'll even need a coctail tonight...lol
but I'll definitely have one anyway ha ha